Title of Invention	FAULT LOCATOR AND ANALYSER EQUIPMENT FOR HVDC LINES
Abstract	The invention relates to a) POWER FAULT LOCATOR UNIT for de-energised HVDC POWER TRANSMISSION for testing and detecting fault location and b) ANALYSER for preventive maintenance of long transmission lines with length upto 2000krn. The invention enables detection of various kinds of developed and developing faults. The POWER LINE FAULT LOCATOR unit is used when a particular HVDC line has tripped due to a fault. This system detects the distance at which the fault has occurred from the point of testing, in km and the nature of fault,(i.e)OPEN type or SHORT type of fault. The Analyser unit connected to HVDC power lines gives the various developing faults on the line in km. It monitors the condition of the line dynamically and graphically. This also gives the degrl~e of damage in 9 discrete levels(Ot08) to give priorities during maintenance. This system is a comprehensive testing instrument for faults on HVDC lines to detect all types of faults and to maintain the line.

Title of Invention

FAULT LOCATOR AND ANALYSER EQUIPMENT FOR HVDC LINES

Abstract

The invention relates to a) POWER FAULT LOCATOR UNIT for de-energised HVDC POWER TRANSMISSION for testing and detecting fault location and b) ANALYSER for preventive maintenance of long transmission lines with length upto 2000krn. The invention enables detection of various kinds of developed and developing faults. The POWER LINE FAULT LOCATOR unit is used when a particular HVDC line has tripped due to a fault. This system detects the distance at which the fault has occurred from the point of testing, in km and the nature of fault,(i.e)OPEN type or SHORT type of fault. The Analyser unit connected to HVDC power lines gives the various developing faults on the line in km. It monitors the condition of the line dynamically and graphically. This also gives the degrl~e of damage in 9 discrete levels(Ot08) to give priorities during maintenance. This system is a comprehensive testing instrument for faults on HVDC lines to detect all types of faults and to maintain the line.

Full Text	FAULT LOCATOR AND ANALYSER EQUIPMENT FOR HVDC LINES The invention is the equipment LINE FAULT LOCATOR SYSTEM FOR HVDC POWER TRANSMISSION lines, is meant for testing and detecting fault location and preventive maintenance of, long HDVC transmission lines with length upto 2000km* It can detect the various kinds of developed and developing faults along the length of HVDC transmission line. The equipment consists of 2 parts: LFault locator part of the system: This part of the system is used when a particular HVDC line being tested has tripped due to a fault. This part of the system detects the distance of fault from the point of testing in kilometers in the LCD display (Refer sl.no. 6/SKETCH 1). It also indicates the nature of fault, (i.e) OPEN type or SHORT type of fault, by operating the switch FAULT TYPE (Refer sl.no.3/SKETCH 1). 2.The Analyser part of the system: The Analyser unit when connected to the HVDC lines gives all the various developing faults along the length of the line in kilometers, in the form of a hard copy print out. There are four formats of print outs representing these various kinds of faults in a variety of user friendly formats. It is also possible to monitor the condition of the line, dynamically by means of the provided graphic LCD display module. Since this part of the system is used for preventive maintenance of HVDC lines it is used generally when the line is healthy. This instrument also gives the degree of damage in 9 discrete levels (0 to 8). This degree of damage helps in giving priorities during maintenance. It is possible to decide on the points of fault which have to be repaired before going to other points of smaller faults. This system is a comprehensive testing instrument for faults on HVDC lines with which it is possible to detect faults on occurrence of a fault and to as well maintain the line during maintenance to prevent occurrence of failure faults, thereby improving the reliability, availability and performance of the HVDC lines avoiding sporadic failures and saving lot of revenue by reducing the number of hours of outages. EXISTING EQUIPMENTS AND THEIR DISADVANTAGES The invention is for overcoming the problems and disadvantages of the existing in the method of fault location and fault analysis on HVDC lines. A study on the various types of faults that can occur on the HVDC lines was made. Having been arrived at the list of faults that can occur on HVDC lines, it was analysed that which of these faults could not be detected with the existing system . Hence we arrived at the list of faults that the existing system could not detect. The list of faults are: 1. Open circuit fault 2. Pole to earth fault 3. Resistive contact jumper 4. Decapping fault 5. Low insulation of insulators 6. Outside object coming in close vicinity to the conductor 7. Earth wire hanging close to the conductor 8. Lightning arrestor failure 9. Failure of PLCC capacitor and other filter capacitor which are connected across the line. 10. conductor oversagging 11. High induction from the adjacent charged multicircuit lines. 12. Fault on spur lines to the main line. The existing systems were generally of the type that are connected permanently to the HVDC lines . They came into operation only after the fault had occurred and the line had tripped due to the fault. And these indicated only some of the dead faults such as pole to earth . But practically they were found to be poor in accuracy and fault finding involved rigorous patrolling of the line. Further once a line had tripped and rectified(the fault at that point) there was no means for rechecking the fault without charging the line(faults occurred in any other points could not be checked by the existing system).But it is a known fact that charging a faulty line is dangerous for both the system as well as the HVDC line connected to it. As it caused a lot more damage than the fault itself. Secondly it is not possible again to check the line after rectification of the fault for proper repair and to determine whether there are no multiple faults on the line other than the one rectified. Finally these ONLINE systems are only for fault detection after occurrence of a fault. They give no data on the presence of other developing faults on the line. Hence it is not possible to undertake preventive maintenance on these lines with these types of fault locators. These ONLINE fault locators have not been able to find all the kinds of faults highlighted above making them non-comprehensive tool for fault location and detection of developed and developing faults on HVDC lines. Moreover, the existing system is laborious, time consuming and not cost effective. THE INVENTION The object of this invention is to detect the faults that may occur on the HVDC lines* The faults that may occur may be categorized into 12 types of faults. 1) Conductor snapping and falling on the ground 2) Jumper Snapping 3) Insulator Decapping 4) Low Insulation of Insulators 5) Lightening Arrestor Failure 6) PLCC Capacitor Failure 7) Conductor Sagging 7) Resistive Contact for Jumper 9) Outside object coming in contact or very near vicinity of the line 10) Earth Wire close to the conductors 11) High Induction from adjacent charged Multi circuit line 12) Fault on Sour Lines to the main line STATEMENT OF INVENTION The equipment thus invented has the following technical features. 1. The equipment is capable of detecting faults on line with length up to 2000km. 2. The equipment is capable of detecting all kinds of dead faults which cause the line to trip., such as 1. OPEN CIRCUIT 2. POLE TO EARTH 3. DECAPPING 4. LOW INSULATION OF INSULATORS 5. LIGHTINING ARRESTOR FAILURE 6. PLCC CAPACITOR OR CVT FAILURE 7. CONDUCTORS OVER SAGGING 8. RESISTIVE CONTACT OF JUMPER 9. OUTSIDE OBJECT COMING IN CONTACT OR CLOSE VICINITY OF CONDUCTOR 10. EARTH WIRE SAGGING CLOSE TO CONDUCTOR 11. FAULTS ON BOTH SPUR LINE AND MAIN LINE IN CASE OF LINES WITH SPUR LINES. 12. JUMPER SNAPPIING 3. The equipment is capable of withstanding heavy induction present on the line being tested. 4. The transmitter has enough power to transmit its power along entire length of the line has suitable amplitude so as to be able to highlight all the developing and developed faults on the line. 5. The equipment is capable of suppressing the switching HVDC noise present on the HVDC LINE. 6. The equipment is capable of detecting all the faults on the HVDC line up to a length of 2000km with a resolution of 100 meters. 7. The equipment is capable of giving the fault distance on a graphic LCD screen directly in kilometers. LINE FAULT LOCATOR SYSTEM FOR HVDC POWER TRANSMISSION LINES The equipment consists of four units: 1. POWER LINE FAULT LOCATOR UNIT HD-1720-APEX-D HVDC-1720-film 2. POWER LINE SIGNATURE ANALYSER UNIT HD-1720-APEX-D HVDC-1720-sam 3. HEAVY DUTY ADOPTER UNIT HD-1720-APEX-D HVDC-1720-adm 4. POWER SUPPLY CUM DIGITAL SIMULATOR UNIT HD-1720-APEX-D POWER LINE FAULT LOCATOR UNIT: This equipment along with the Heavy duty Adopter and Power supply unit when connected to de-energized power line can indicate faults such as OPEN CIRCUIT or SHORT CIRCUIT at any point up to 2000KM long transmission line. These unit controls the Adopter who is connected in tandem to transmit lOkilo volts and 500 kilowatts of power pumped in to DC transmission line to detect faults up to 2000 km. The fault locator equipment is equipped to indicate any of the types of faults namely, open circuit, pole to earth and decapping and the distance at which the fault has occurred from the testing end. POWER LINE SIGNATURE ANALYSER UNIT: This equipment houses a graphic LCD display. This equipment when connected in tandem with Adopter to the power line gives the signature (that is the characteristic of the line) of the entire length of the line with 100 meter resolution. It gives four print outs such as 1. Highlights of fault indication in KM 2. Signature of the entire length of the line in 0.1km resolution 3. Scan print out of the entire length of the line with the lOOmetre resolution. 4. The map of the homogeneity of the line in 9 discrete vertical steps (0 to 8) Indicating the non-homogeneity of the line. The equipment has got all facilities to analyse the entire function of signature analysis. An output is provided for printer connection and another output is provided for computer interface. Dedicated computer software is provided to load the signature of the line and analyse all aspects regarding the non-homogeneity of the line. It is also possible to view the signature of the line dynamically in the graphic LCD display. HEAVY DUTY ADOPTER UNIT: This equipment is connected in between fault locator or analyser and transmission line. This equipment houses the transmitter and line matching unit and it also houses the filters to suppress HVDC switching noise namely, electrical switching noise. It produces enough power to illuminate a 2000km transmission line to get return which are above noise level to the sending end, for which the Adopter has all necessary controls. POWER SUPPLY CUM DIGITAL SIMULATOR UNIT: This unit houses a maintenance free battery and necessary charging unit from mains. It has in -built simulator for in house testing of the Fault locator unit and the Analyser unit. POWER LINE FAULT LOCATOR UNIT: (SKETCH 1) The Powerline fault locator unit consists of the following controls: 1. SET POWER: (REFER SL. NO. 1) This consists of a rotating switch, which can be set in three positions. Namely 1. LOW POSITION 2. NORMAL POSITION 3. HIGH POSITION The respective positions are selected depending on the length of the HVDC line required to be tested for finding the fault. By keeping the control in LOW position it is possible to test the faults occurring at any point within 100 km s of the line. For testing the faults between l00 kms and 2000 kms on the HVDC lines the NORMAL or HIGH position is selected. 2. POWER ON: (REFER SL. No.2) The function of this switch is as follows. This switch when put to 'ON' position switches on the power to the equipment. The power to this equipment is got from a 12 volts 26 Ah dry fit maintenance free battery housed in the POWER SUPPLY/SIMULATOR UNIT. This 12 volts got from the POWER SUPPLY/ SIMULATOR UNIT is connected to the Fault locator unit through the power switch. In the Fault locator unit this 12 volts is converted to suitable voltages necessary to operate the system. This 12 volts is got in to the Fault locator unit from the 12 pin connector present on the Fault locator unit (Reference No. 9 in the figure.) 3. FAULT TYPE (REFER SL. NO. 3) This is an important part of the invention. By operating this it is possible to ascertain the type of faults that has occurred on the HVDC lines. This is a rotating switch having three positions marked 1. SET 2. OPEN 3. SHORT In SET position it is possible to ascertain the distance of fault. From the OPEN and SHORT position of the switch it is possible to ascertain whether the fault that has occurred is of OPEN type such as JUMPER OPEN, (dead fault) CONDUCTOR CUT (dead fault) LOOSE JUMPERS, DECAPPING OPEN VARIETY AND RESISTIVE CONTACT OF JUMPER or SHORT type such as POLE TO EARTH FAULT, DECAPPING SHORT VARIETY, EARTH WIRE HANGING CLOSE TO CONDUCTOR, LIGHTINING ARRESTOR FAILURE, COUPLING CAPAPCITOR FAILURE, OUTSIDE OBJECT COMING CLOSE TO VICINITY OF THE CONDUCTOR, LOW INSULATION OF INSUALTORS, AND CONDUCTOR SAGGING. If the fault distance appearing in SET position continues to appear in OPEN position and does not appear in SHORT position then the fault is termed as OPEN type of fault. It could be due to one of the above mentioned types of faults under OPEN category. If the fault distance appearing in SET position continues to appear in SHORT position and does not appear in OPEN position then the fault is termed as SHORT type of fault. It could be due to one of the above mentioned types of faults under SHORT category. 4. SET FAULT: (REFER SL. NO. 4) This is one of the most important and crucial aspects of the invention. A fault may occur at any point in the entire length of 2000km of the HVDC lines. The invention enables to fix the point of fault with accurate precision using the SET fault, so that the remedial measures can be taken at the point where the fault has occurred. The invention not only enables to fix the point of fault but also enables the same to be carried out in seconds, thus saving valuable time which is crucial when a fault occurs in the lines. It not only saves time but also saves lot of revenue in crores of rupees to the electrical utility. The SET FAULT is a ten turn potentiometer. The invention also includes a switch which can be set to LOW or HIGH position, while using the SET FAULT. Normally the SET FAULT is operated by keeping the switch in LOW position. If no reading appears on the LCD display (REFER SL. NO. 6).THIS ITSELF IS AN INVENTIONthe switch is changed to HIGH position. As the SET fault is turned in the clockwise direction the reading will appear on the LCD display to indicate at what point or distance of line the fault has occurred. For example, if a fault has occurred at a point, which is 100.1 km from the starting point of the line, this is indicated in the LCD display. This figure will not change even if the SET FAULT is rotated further; thus it is possible to find the place of fault on the lines with absolute precision. This operation is not only accurate but also is easy to operate by even laymen. Once the place of fault is known as indicated in the LCD display, remedial measures will be taken without loss of time. Thus the invention is accurate, time and revenue saving and easy to operate and depending on the type of fault it also helps to save precious life of human beings or cattle which may be affected by fault occurring in the HVDC lines. The fault as seen on the LCD display can be noted down for future use. SET FAULT can also be used while using the SIMULATOR for in-house testing. The SET FAULT has two more features namely OVERSET and FAULT SET. If the SET FAULT is not operated properly the OVERSET will glow to indicate the same. The FAULT SET will start glowing to indicate that the point of fault is about to be displayed and thus the operator is alerted. 5a) SET BLANKING; (REFER SL.NO. 5) The SET BLANKING is another innovative aspect of the invention. By using this it is possible to detect the fault at any desired length of the HVDC line and blank the length of the line where there is no need for the test of the faults. This is further explained as follows. The HVDC lines runs through thousands of kms from the starting point to the end point. In case the line develops multiple faults along its length without the above feature it is only possible to see one fault, that is, the first fault the closest fault to the testing point. It might not be possible to see beyond this fault for multiple faults. So by having this feature it is possible to blank this fault reading to search for multiple faults on the line. For example, say we are testing a line of length 1500kms. Suppose a fault reading of 100 kms appears in the FAULT LOCATOR. It is not possible to test the line from 100 kms to 1500 kms for faults. So by blanking the reading of 100 kms by using the ten turn blanking potentiometer and selecting the corresponding position on the BLANKING DISTANCE switch (REFER SL. NO.7) it is possible to blank the distance of 100 kms and check for other faults from lOOkms to 1500kms. Further this blanking facility is very useful for lines having spur line to the main line(that is T-offs) 5b) SCAN ON/OFF This switch helps in scanning every 3 kms of the line, in the LCD DISPLAY. 6) 41/2 DIGIT LCD DISPLAY This LCD display displays the fault distance in kms. 7) BLANKING DISTANCE: This switch is a 6-position switch marked 0km, 400km, 800km, 1200km, 1600km and 2000km. Each position indicates the starting distance of blanking and further 400 km of blanking is got from the SET BLANKING POT. 8) POWER: This switches on power to the instrument on connecting the 12 pin output connector to either the power supply/simulator unit's 12 pin connector for simulated testing or by connecting it to the adopter's unit 12 pin connector and connecting the power supply simulator unit's 5 pin pig tail connector to the adopter unit's 5 pin connector for testing HVDC lines. 9) TO ADOPTER: This 12 pin connector is connected to the 12 pin socket on the POWER SUPPLY/SIMULATOR unit for simulated testing. This 12 pin connector is connected to the 12 pin connector socket on the adopter for testing HVDC lines. TESTING OF SPUR LINES For testing lines with spur lines it is necessary to have previous healthy line results. For a healthy line the readings indicated by the Fault locator are 1. Joint of Spur to the main line 2. Spur line end 3. Main line end So, to test a spur line, it is necessary to have the above three readings of the line, when the line is healthy. For example, Consider a line of length 40 km having a spur of 10 km at a distance of 20 km on the main line. Now consider the above line during healthy conditions. Now to test this line, keep the Set power switch in normal position, Set Fault pot fully anti clockwise position and Set fault switch in LOW position. Select ON position in the POWER switch (reference No. 8). Put the Blanking ON/OFF Switch to ON position. Set the ten turns Blanking pot too fully anti clockwise position. Now increase the SET FAULT pot, so as to get the point of Spur joint in the display. To get this reading the Fault set pot has to be set to a level higher than that normally required. Next turn the ten turn Blanking pot in the clockwise direction until the above reading just disappears from the display. Further, set the Fault set pot to get the next closer reading, that being the Spur line end, that is, 20 km + 10 km = 30 km. This indicates that the fault has occurred at the spur end. Now turn the ten turn Blanking pot further, to remove the above reading of 30 km. Then set the Fault set pot to get the next higher reading of 40 km, which is the end of the Main line. Note the above three readings for future reference. NOTE: Spur joint reading always appears in short position of the Fault type switch. Whereas the Main line end and Spur line end appear in either open or short position, depending on the type of end termination. POSSIBILITIES OF FAULTS ON SPUR LINES: There are three points on a spur line where faults could occur. 1. Between testing end and spur joint 2. Between spur joint and Main end 3. Between the spur joint and spur end Testing case 1 type of faults: For faults between testing end and spur joint the fault distance is directly got on the display as the first result and with further Blanking it will not be possible to get the spur joint, spur line end and main line end readings. Testing case 2 type of faults: The faults between the spur joint and Main end, following the above procedure, first the spur joint is got. After Blanking the spur joint the spur end is got. After Blanking the spur end the fault point is got and it is not possible to get the main end Testing case 3 type of faults: For faults between the spur joint and spur end, following the above procedure, first the spur joint is got. After Blanking the spur joint the point of fault is got. After Blanking the point of fault the main line end is got, indicating that the fault is between the spur joint and spur end. FINDING DECAPPING FAULTS IN POWER LINES The line fault locator may be used to find decapping faults in transmission lines, where the line is hanging in the air without touching ground. PROCEDURE Now connect the fault locator to the lines as indicated previously Now get the fault readings of the line. If the fault locator under normal setting shows the end of the line then it is presumed that line conductor is upto the end and it is not snapped any where or it is not touching earth any where .Then it could be presumed that a decapping fault may exist on the lines. First get the end reading of the line by turning the Fault set pot in the clockwise direction. Now after getting the end reading turn the Fault set pot further from the previous setting to see if any other readings other than the end of the line appears. If any reading do appear note these readings, then this may be a decapping fault. This fault distance could appear either in short or open positions of the fault locator depending on the nature of decapping. POWER LINE SIGNATURE ANALYSER (SKETCH 2) 1. POWER ON: This switches on the power to the equipment, when the 12 pin connector on the analyser is connected to either the adopter for testing of the HVDC lines or to the 12 pin connector on the power supply or simulator unit for testing in-house. 2a. MODE FIXED/DELAYED: This toggle switch is used to select whether we want the signature of a particular length of the line(DELAYED) or the full length of the line(FIXED). 2b. INITIAL DELAY: This facility is provided so that any part of the line could be moved in to the center of the LINE VISION DISPLAY(SL.NO. 2) and viewed dynamically and with better resolution. 2c. SET: This INITIAL DELAY is achieved by this 10 turn potentiometer and a six position switch marked 0 km to 1600 km. When the line length to be viewed is between 400km to 800km then the SET has to be kept in 400km. If the line length to be viewed is 1200km to 1600km then the SET has to be kept in 1200km. Hence this enables the viewing of every 400km of the line in the display. This choice of the length being selected for viewing in the LINE VISION DISPLAY is displayed in a 41/2 digit LCD display (SL.NO. 3) for better clarity. 3a. SET GAIN: This potentiometer is slowly turned in clockwise direction to get the fault readings on the display. 3b. AUTO/MANUAL: If MANUAL is selected and the SET GAIN pot is set so as to set the reflection from the end of the line to view in full screen on the display. 3c. AUTO GAIN: If AUTO is selected in the AUTO/MANUAL switch the AUTO GAIN switch is put to one of the 6 positions marked 1 to 6 (six positions denotes the level of clarity of the signature in the chronological order), the line is viewed in the full screen on the display. This selection helps in comparitive study of the developing faults on the line. For example, if we take a signature today and take another signature a month later, it is possible to take both the signature with the same gain settings. That is, position 1 to 6. Taking signature in same settings helps in determining whether a developing faults on the line has increased in level from its previous value. For example, we take signature of a line today with Auto gain switch in 5th position. After a month we take the signature of the same line with Auto gain switch in 5th position. We will be able to determine which point on the line has increased in fault level and whether any other new points have appeared further to the existing faults. 3d. PRINTER ON: This switch when put in ON position, switches on power to the printer through the printer chord pig tail provided. 4. PRINT/DISPLAY: This switch when put in "PRINT" position enables to take the printouts and when put in "DISPLAY" position enables to view in the display. 5. RESET: This is used to reset the system for proper operation. 6. LCD DISPLAY: This is LCD display which displays the line dynamically and graphically. 7. TRASMIT AND STORE: After connecting the Heavy Duty Adopter unit to the HVDC lines and connecting the Line Vision Signature Analyser unit to the Adopter unit, Pressing this button will load the reflected pulses received from the line to the Line Vision Signature Analyser unit. 8. HIGHLIGHTS: Pressing this highlight switch will give the print out of all the developing / developed points of faults in kilometers along with the degree of fault.(This switch should be pressed only after connecting the Printer cable and the printer power chord to the printer and switching on the PRINTERJ3N/OFF (Refer Sl.No. 3d/ SKETCH 2) switch to ON position) 9. SIGNATURE: By connecting the printer and pressing the switch will give corresponding print of the SIGNATURE on the printer. 10. SCAN: By connecting the printer and pressing the switch will give corresponding print of the SCAN on the printer. 11. MAP: By connecting the printer and pressing the switch will give corresponding print of the MAP on the printer. 12. STORE: By connecting the laptop computer's Parallel port to the printer cable and pressing this switch will store the data to the computer. 13. PRINT DISTANCE SELECT: This is a 6 position rotary switch marked 0km,200km,400km, 800km, 1200km, 1600km. Depending on the line length this switch is selected so as to save the stationary while printing. 14. CONTRAST: This is used to set the contrast of the LCD DISPLAY. 15: TO ADOPTER UNIT: This is a 12 pin connector, connected to the Adopter unit with the cable provided for testing HVDC lines. HEAVY DUTY ADOPTER UNIT (SKETCH 3) Since the transmission lines are tested for faults offline it is necessary to illuminate the lines for two purposes. They are as follows, 1. to locate the fault by using the Power line Fault locator unit, 2. to ascertain the signature (the characteristics of the line) using the Power line signature Analyser unit. The Adopter unit is connected between The Fault locator unit and the transmission line Or The Line Vision Signature Analyser unit and the transmission line This equipment houses the transmitter and the line matching unit. The function of this unit is fourfold 1. This unit suppresses the induction( the voltage produced in the line due to the power flowing in the adjacent lines) so that safe working of the personnel using the equipment is ensured. 2. Generates the signal necessary to illuminate the line and to get back the reflections and give these signals got from the line to the Fault locator unit or analyser unit for processing. 3. The Alter in this equipment suppresses the switching noise of the HVDC lines.( as DC is converted to AC it generates a noise which creates disturbance in the transmission lines). This disturbance is overcome by the Adopter unit. 4. It also matches the transmitter to the impedance (this is the line characteristics impedance) of the line. This unit produces enough power that illuminates a 2000 km transmission line and gets back the pulses from the line. The various controls that are provided in this equipment and their working are as follows • 5 PIN POWER SUPPLY CONNECTOR (REFER SL. NO. 1) This is located on the left hand top corner of the unit. The pigtail 5 pin connector of the Power supply cum simulator (refer sketch no. 4) unit is connected to this 5 pin socket. • FILTER ON/OFF( REFER SL.NO 2 ) This is switched to "ON" position when the lines are long and noisy, i.e the disturbance caused by other transmission lines or due to other causes. • 12 PIN SOCKET CONNECTER ( REFER SL. NO. 3) This is located on the left bottom corner of the unit. This is connected either to the fault locator or the analyser units 12 pin connector • SET POWER (REFER SL. NO. 4) This supplies power on the lines and is three position rotary switch market 1. Low 2. Normal 3. High Depending on the length of the line or the level of the noise the power is set by keeping the position in low or normal or high position. • INDUCED VOLTAGE METER( REFER SL NO 5) This meter indicates the presence of induction on the HVDC lines • EARTH (REFER SL NO 6) There are earth terminals in the unit. One is on the right bottom corner and the other is in the right side of the unit Both these terminals are connected to the good station earth with the earth cable and clamp provided before connecting the unit to the HVDC lines. • 12 PIN CONNECTOR MOUNTED ON EPOXY GLASSf REFER SL NO. 7) This is connected to the HVDC lines to be tested with connected cable and hook rods provided. • TRANSMIT METER (REFER SL NO. 8) This meter indicates the transmission of energy from the equipment to the HVDC lines POWER SUPPLY AND SIMULATOR UNIT (SKETCH 4) This equipment consists of a battery for supply of power to the lines to be tested and for the equipments used and a simulator for inhouse testing. The invention relating to these two parts and the working of the same are as follows. 1. MAINS ON: This is used to switch on AC mains to the battery charger. 2. POWER ON: This should be put on ON position for switching on power to the system. 3. SIMULATED DISTANCE: This is a 3 position switch marked 200km, 800km and 1400km. Putting this switch to each of these positions generates a distance of 200km, 800km and 1400km(approx.).This is used for in-house testing of the system. 4. MCB: This is a protective device used to protect the battery against short circuit. It should be always on ON position during operations. 5. TO FAULT LOCATOR/ANALYSER UNIT: This 12 pin connector is connected to either Power line Fault locator unit or Power line signature Analyser unit for in-house simulator testing. 6. MAINS INPUT: The mains 230 VOLTS 50 Hz AC mains to the batter charger. 7. BATTERY: INDICATORS: Charged: This green LED always lights up when the 'POWER ON' SWITCH IS PUT TO 'ON' position indicating charged battery. Discharged: This red LED always lights up when the 'POWER ON' switch is put to 'ON' position indicating the battery is in discharged condition. Charging: This red LED lights up during charging of the battery and it gradually dims away on battery charging. A FUSE OF 2 AMP IS ALSO PROVIDED for AC mains protection. WORKING OF THE BATTERY: The testing of the lines for faults is done offline. During the testing of fault in the lines the power has to be supplied to the equipment. This is being done by the battery. Provision is made to check whether the battery is fully charged before use. The 'MAINS ON1 switch switches on the AC mains to the battery charger. 'MAINS INPUT' socket is connected to a 230 volts 50 Hz AC mains(with the mains chord provided) for charging the battery. WORKING OF THE INVENTION Take the POWERLINE FAULT LOCATOR SYSTEM near the HVDC lines to be tested. Now ground the HVDC lines with the EARTH GOS. Select a good station ground. Take care to see that the grounding is proper. Now connect the other end of the Grounding Clamp to the Heavy duty adopter's(SKETCH3)two Earth terminals(SLNo.6/SKETCH 3). Now connect the Heavy duty Adopter's 12 pin connector mounted on epoxy base( Sl.No.7) to the end of the hook sticks with a 12 pin plug provided. Connect the hook rod to the HVDC line. Now interconnect the Power supply cum simulator unit(SKETCH 4) and the Heavy Duty Adopter unit with the 5 pin pigtail connector provided on the Power Supply cum Simulator unit. Now connect the Power line Fault locator unit(SKETCH 1) with the Adopter unit with the 12 pin connector provided(Sl.No.9/SKETCH 1). Then make all initial settings on both the Adopter unit and the Power line Fault locator unit depending on the line length. The initial settings of the Power line Fault locator unit are as follows. i) SET POWER - NORMAL ii) FAULT TYPE - SET iii) ROTARY POWER SWITCH - ON iv) BLANKING - OFF v) SET FAULT POT - FULLY ANTI-CLOCKWISE vi) GAIN LOW / HIGH - LOW The initial settings of the Adopter (SKETCH 3) are as follows :- i) POWER - Depending on line length. ii) FILTER ON / OFF - ON The initial settings of the Power supply cum Simulator unit (SKETCH 4) are as follows :- i) MCB -ON ii) Power - ON Now open the grounding of the HVDC LINE by opening the earth GOS. Now switch the 'POWER ON' switch in the Powerline Fault locator to 'ON Position'. Now turn the SET FAULT pot so as to get a reading in the 41/2 digit LCD display such that the reading in the display changes from 1888.8 to a fixed reading. Note the reading. Similarly put the SET Fault switch to 'Open' and 'Short' positions and note the corresponding readings. This distance is the distance of fault in a faulty line or is the length of line in a healthy line. The type of fault is determined from the reading obtained in the OPEN & SHORT positions. If the reading in open position is same as SET position the fault is said to be OPEN CURCUIT fault or if it is otherwise it is said to be earth fault. For connecting the Power line Signature Analyser (SKETCH 2) to the line, disconnect the connection between the Adopter and the Power line Fault locator unit at the fault locator end. Connect this 12 pin connector from the Adopter to the 12 pin connector (socket) on the Power line Signature Analyser (Sl.No. 15/SKETCH 2). Now put the Analyser's (SKETCH 2) Print / Display switch (Sl.No. 4/SKETCH 2) to display mode. Select suitable button on the Analyser to match the end of the line so as to obtain the end of the line reflection in the display. Now select Manual / Auto switch Sl.No. 3b/Sketch 2) to 'Manual' position. Set the SET GAIN (Sl.No. 3a) pot from fully anticlockwise to clockwise so as to make the end of line reflection to just reach full screen. Now put the PRINT / DISPLAY switch (Sl.No. 4) to 'Print' Position and press and release the 'RESET' (Sl.No. 5) button and then the Transmit / Store button( Sl.No. 7). Now the line signature gets loaded into the Analyser and the end readings are displayed in Line vision display(Sl. No. 16). Now use the other 4 buttons marked 'Highlights'(Sl.No. 8), 4Signature'(Sl.No.9), 'Scan'(SLNo.lO) & 'Map'(Sl.No. 11) buttons to get their corresponding prints on the printer. Before getting printout it is necessary to connect the 2 pig tail cables from the Analyser to Printer Port Cable and Printer Power input to the printer. Then switch on the 'Printer On' switch in the Analyser to 'ON' position. Connect the printer port cable to the computer parallel port using the cable provided and press COMPUTER STORE (Sl.No.12/SKETCH 2). Ten results are taken automatically from the Power line Signature Analyser unit and stored in the computer. The computer Software analyses these 10 sets of readings and gives out all the salient points on the line removing all other noise present on the line. Explanation of the faults occurring on HDVC lines and how they are indicated by our instrument HT-1720-APEXD I.OPEN CIRCUIT FAULT: a) EXPLANATION OF THE FAULT: In the case of open circuit faults the HDVC lines conductor cuts in the middle and hangs in the air without coming in contact with either the tower or the earth beneath .This can be of 2 types 1. Conductor cutting 2. Jumper snapping 1.Conductor cutting: Due to various reasons the conductor itself can get cut. Thereby breaking the electrical path. 2 Jumper snapping: Approximately for every kilometer a jumper is used to connect conductors along the length of the line. These jumpers are clamped at both ends to the conductor by means of clamps and bolts. In case any of these clamps or bolts give way they result in the jumper hanging in the air creating an open circuit fault. b) INDICATIONS IN OUR INSTRUMENT: Powerline Fault locator unit: This instrument indicates the variety of fault as a distance in kms. Example:- LINE LENGTH - 100km OPEN CIRCUIT - 35km SET OPEN SHORT 35 35 In the above example the line is of length 100km with a fault of open circuit at 35 kms. The instrument Indicates the distance of fault in the SET position and the type of fault is determined depending on whether the reading corresponding to SET position appears in either OPEN or SHORT position. Since in the above example it appears in OPEN position the fault is said to be the OPEN CIRCUIT FAULT and at a distance of 35kms. CONCLUSION:- This kind of OPEN circuit fault can be detected by the fault locator part of instrument. The example of the OPEN CIRCUIT FAULT when the line is connected to the POWER LINE SIGNATURE ANALYSER unit is as follows: As explained earlier the Power line Signature Analyser gives the output in four formats. 1. HIGHLIGHTS: This gives all the faulty points on the line as well as the end of the line with their degree of damage at that point of fault(in the line) in kilometers. 2. SCAN This gives a raw printout of the signature of the line in numeric form. In this printout each " - " represents 100 meters. Hence each line of the printout represents 10 kms. Each point of fault is represented by a train of numbers(0 to 8). The point of fault is the centre of this train of numbers. 3. MAP This is the graphical representation of the scan. 4. SIGNATURE This is a sophisticated scan print. The point of fault is pinpointed in this format. OPEN CIRCUIT FAULT: Our transmission of pulse from the equipment is in the form of an inverted 'Y' This pulse travels along the length of the line and if it faces an open circuit during its travel along the length of the line it reflects back as a inverted 'Y' from the point of open circuit. This point of open circuit could either be the far end of the line kept open or dead open circuit fault along the length of the line. If the reflection is from the end of the line it is the distance in the highlights ,signature ,scan and map will be the length of the line, else, if it is a fault along the length of the line, then the distance indicated in the map, signature, scan, highlights will be equal to the distance of fault from the point of testing in kilometers. EXAMPLE: Let us consider a line of length 350km. Suppose the end of the line is kept open, then the output got from the signature analyser unit (that is signature, scan, highlights, map) will be as follows in the following pages. The end of the line is kept open and it is signified by an inverted Y. The line is healthy and we have the end of the line signifying open circuit. REFER: CHART 1 - MAP CHART 2 - SCAN CHART 3 - SCAN CHART 4 - HIGHLIGHTS CHART 5 - SIGNATURE CHART 6 - SIGNATURE SHORT CIRCUIT FAULT: Our transmission of pulse from the equipment is in the form of an inverted 'Y'. This pulse travels along the length of the line and if it faces a SHORT circuit during its travel along the length of the line it reflects back as a 'Y' from the point of SHORT circuit. This point of SHORT circuit could either be the far end of the line kept short or short circuit fault along the length of the line. If the reflection is from the end of the line, it is the distance in the highlights, signature, scan and map will be the length of the line, else, if it is a fault along the length of the line, then the distance indicated in the map, signature, scan, highlights will be equal to the distance of fault from the point of testing in kilometers. REFER: CHART 7 - MAP CHART 8 - SCAN CHART 9 - SCAN CHART 10 - HIGHLIGHTS CHART 11 - SIGNATURE CHART 12 - SIGNATURE INSULATOR FAULT : Since our pulse transmission is in the form of an inverted 'Y' any change in homogenity at any point along the length of the line depending on the impedance change can either be 'Y' or an inverted 'Y\ If the impedance at any point of reflection is lower than the characteristic impedance of the line then the reflection from that point will be in the form of a Y' or if it is higher than the characteristic impedance then it is an inverted YComing to insulators aspect it is found that in a string of insulators a few of insulators can develop low insulation causing power leaks at that point. This point of power leakage are detectable from our signature* The impedance change caused by these failed insulators is of very low values. These are detectable by the equipment only when we go to very high gain settings such as auto gain 5,6 ((3c) SKETCH 2) and it is found in most of the cases that these points appear as inverted Y% i.e., open type. As they do not affect the characteristic impedance at that point, so as to bring it below the value of characteristic impedance of the line. REFER AUTO GAIN 5 REFER AUTOGAIN 6 CHART 13-MAP CHART 19-MAP CHART 14 - SCAN CHART 20-SCAN CHART 15 - SCAN CHART 21-SCAN CHART 16 - HIGHLIGHT CHART 22-HIGHLIGHT CHART 17 - SIGNATURE CHART 23-SIGNATURE CHART 18 - SIGNATURE CHART 24-SIGNATURE CONCLUSION: As the arm of the "Y" is pointing towards open side in the MAP, the distances of developing fault have to be taken from the open side in the Highlights. Hence, the points 40.8, 42.9 and 244.7 are the pints of developing fault, with degree of fault 3. The degree indicates the intensity of damage of the line at that point( If the damage is "8" it is presumed to be a dead fault). OPEN CIRCUIT: LOOSE JUMPER In case of a loose jumper the overall series resistance of the conductor increases at the point of loose jumper along the line. As our pulse travels along the length of the line and when it arrives at the point of loose jumper it faces a change in homogenity causing major part of the pulse to reflect back from that point. The remaining point of the pulse travels to the end of the line and gets reflected back from the end of the line. Since the pulse has weakened, the end reflection will be lower in level compared to that reflected from the point of loose jumper. This reflected pulse will be in the form of an inverted "Y". TEST RESULT Pole Open Highlights 2.8(8) 350.0(8) Pole Short Highlights 0.6 (8) 348.1(8) 352.0(8) Note: The fault distance 350km in the Pole Open side indicates the open circuit fault. TEST RESULT Pole Open Highlights 2.5(8) 348.1(8) 352.1(8) Pole Short Highlights 0.6(8) 350.0(8) TEST RESULT Pole Open Highlights 1.5(8) 40.5(3) 143.0(3) 245.0(3) 350.0(8) Pole Short Highlights 0.5(8) 41.4(3) 044.2(3) 141.5(3) 144.6(3) 243.5(3) 246.5(3) 348.5(8) 351.5(8) TEST RESULT POLE OPEN 30KM 40KM —3 50KM 60KM 100KM 10KM 80KM 90KM 200KM 30KM 3 50KM 80KM 300KM 40KM 60KM 70KM 80KM 90KM 400KM TEST RESULT POLE SHORT —8 10KM 40KM 3 3 50KM 60KM 70KM 80KM 90KM 100KM 10KM 20KM 30KM 40KM 90KM 200KM 3 3 50KM 60KM 70KM 300KM 10KM 20KM 30KM 40KM 8 . 60KM 70KM 80KM 90KM 400KM TEST RESULT Pole Open Highlights 1.5(8) 040.5(5) 143(5) 245(5) 350(8) Pole Short Highlights 0.5(8) 41.4(5) 044.2(5) 141.5(5) 144.6(5) 243.5(5) 246.5(5) 348.5(8) 351.5(7) TEST RESULT Pole open highlights 2.7(8) 236.6(7) 348.6(6) Pole short highlights 0.7(8) 234.5(7) 239.3(6) 345.6(6) 351.5(7) CLAIMS 1) A Power line fault locator system comprising i) Power line fault locator unit ii) Power line signature analyser unit iii) Heavy duty adopter unit iv) Power supply cum digital simulator unit is capable of detecting and locating the various types of faults offline, such as herein described on HVDC transmission line upto the distance of 2000kms with a resolution of 100m, further the said system is capable of simultaneously detecting ,locating and identifying the multiple faults, if any on HVDC transmission line(s). 2) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the conductor snapping and falling on the ground. 3) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the conductor snapping. 4) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating insulator decapping. 5) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the fault of low insulation of insulators 6)A Power line fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the lightening arrester failure. 7) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the PLCC capacitor failure. 8) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the conductor sagging 9) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the failure of resistive contact of jumper. 10) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating any outside /foreign body /object coming in contact or very near vicinity of the line 11) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the earth wire portion coming close to the conductors 12) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of working under high induction from adjacent charged multi circuit transmission lines and other line crossings. 13) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating faults both on the main line as well as on the spur lines in case of lines with spur lines. 14) The Power line fault locator unit as claimed in claim 1 along with the heavy adopter and power supply unit is capable of indicating the faults such as open circuit or short circuit at any point up to the 2000km long transmission line when connected to deenergised power line. 15) The Power line signature analyser unit as claimed in claim 1 houses a LCD display and when connected in tandem with adopter to the power line gives the signature (the characteristic of the line) of the entire length of the line with the 100m resolution. 16) The Heavy duty adopter unit as claimed in claim 1 is connected in between fault locator or analyser and transmission line and further houses the transmitter and line matching unit and Alters to suppress HVDC switching noise and any other 50hz induction present on the line. 17) The Power supply cum digital simulator unit as claimed in claim 1 further houses a maintenance free battery and necessary charging unit from mains and an in-built digital simulator for in-house testing of the fault locator unit and analyser unit. 18) A method of detecting, locating and identifying the nature of the fault(s) on HVDC transmission line upto the distance of 2000km with a resolution of 100m by operating a line fault locator system as claimed in claim 1. 19) The method as claimed in claim 18 wherein a rotating switch of the power line fault locator unit can be set either in low position or normal position or high position. 20) The method as claimed in claim 18 wherein the detecting and locating the fault at any point within 100km of the line by setting the rotating switch of claim 19 at low position. 21)The method as claimed in claim 18 wherein the detecting and locating the fault at any point from 100km to 2000km on the HVDC lines by setting the rotating switch of claim 19 either in normal or high positions. 22) The method as claimed in claim18 wherein the fault type is ascertained by operation of another rotating switch having three positions marked as SET, OPEN and SHORT. 23) The method as claimed in claim 18 wherein the open type fault appears only in open position at a fault distance appearing in SET position and does not appear in SHORT position. 24) The method as claimed in claim 18 wherein the SHORT type fault appears only in SHORT position at a fault distance appearing in SET position and does not appear in OPEN position. 25) The method as claimed in claiml8 wherein a switch SCAN ON/OFF is operated to check for faults in the HVDC transmission lines by moving a window equal to 3km along the entire length of the line continuously with the help of the set blanking potentiometer controL(ref.s.l.no.5a/sketch I) 26) The method as claimed in claimlS wherein a LED lamp, OVERSET is provided to indicate the setting of the SET FAULT potentiometer beyond the minimum required threshold level. 27) The method as claimed in claiml8 wherein a 4 l/2digit LCD 7 segment numeric display is provided by means of which it is possible to get directly the distance of faults in kms directly. 28) The method as claimed in claim from 18 to 27 wherein for the detecting and locating the multiple faults , situated or located at various positions throughout the length of HVDC transmission line(s) by using SET BLANKING technique. 29) The rotating switch of claim 22 when placed at SET position, it ascertains the distance of the fault. 30) The rotating switch of claim 22 when placed at OPEN position, ascertains whether the fault that has occurred is of open type such as jumper open (dead fault), conductor cut (dead fault), loose jumpers ,de-capping open variety, resistive contact of jumper and like. 31) The rotating switch of claim 22 when placed at SHORT position ascertains whether the fault that has occurred is of short type such as pole to earth fault, decapping short variety, earth wire hanging close to conductor, lightning arrestor failure, coupling capacitor failure , outside object coming close to the vicinity of the conductor, low insulation of insulators, conductor sagging and like. 32) The Power line signature unit as claimed in claim 1 houses a LCD display displaying various faults on the line in graphical and dynamic form on the display. 33)The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the HIGHLIGHT switch will give highlight printout of all the developing /developed points of faults in kilometers along with the degree of fault. 34) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the SIGNATURE switch gives the print out of signature which will give the signature point of all the developing/developed points of faults in kilometers along with the degree of fault. 35) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the SCAN switch which will give the scan printout of all the developing/developed points of faults in kilometers along with the degree of fault. 36) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the MAP switch which will give the map print out of all the developing/developed points of faults in kilometers along with the degree of fault. 37) The Power line signature analyser unit as claimed in claim 1 houses a switch namely COMPUTER STORE which on pressing will load 10 samples of line data from the analyser unit to the computer for complete analysis of the line. 38) The Power line signature analyser unit as claimed in claim 1 when connected to a laptop computer interface can detect and locate all types of faults in the environment of heavy switching noise and any other noise present on the line using appropriate software. 39) The Power line signature unit as claimed in claiml houses a switch namely transmit store that will load the line signature to the equipment. 40) The Power line signature analyser unit as claimed in claiml does the process of transmitting high voltage power pulses on HDVC lines receiving the reflected pulse and processing them for detection of various developed and developing faults. 41) The Power line signature analyser unit as claimed in claiml houses a switch AUTO/MANUAL which when kept in MANUAL position and with a 10 turn potentiometer with turn indicator it is possible to ascertain the various developing faults along the length of the line with their degree of damage (i.e) with the marker on the potentiometer set to various positions starting from 1 to 10 positions upto 10 turns. It is possible to ascertain all the faults starting from the highest degree to the lowest degree and it is also possible to periodically ascertain the increase in degree of fault at various points along the length of the line with similar settings of the 10 turn potentiometer. 42) The Power line signature analyser unit as claimed in claiml houses a switch AUTO/MANUAL, which when kept in AUTO position, it is possible to ascertain the various developing faults along the length of the line with their degree of damage, when it is set to various positions from 1 to 6. It is possible to ascertain all the faults starting from the highest degree to the lowest degree and it is also possible to periodically ascertain the increase degree of fault at various points along the length of the line with similar setting of the switch. 43) The Power line signature analyser unit as claimed in claiml has DISPLAY mode switch which enables the graphical viewing of the lines in dynamic form. In this mode it is possible to see fixed lengths of line in case of lines upto length of 2000km in 5 steps. The steps being 1) 0km to 400km 2) 400km to 800km 3) 800km to 1200km 4) 1200km to 1600km 5) 1600km to 2000km This is in the flxed mode of operation. 44) The Power line signature unit as claimed in claim 1 has DELAY mode of operation it is possible to bring only part of the line to the center of the display. This is achieved by means of lOturn potentiometer marked SET and switch FIXED/DELAY mode. The switch has 6 positions marked 0,400,800,1200,1600,2000 and the lOturn potentiometer marked SET gives maximum delay of 4S0km. 49)The Heavy duty adopter unit as claimed in claim 1 houses a filter ON/OFF switch which when kept in ON position filters the noise when the lines are noisy and long, 50)The Heavy duty adopter unit as claimed in claim 1 indicates the presence of induction on HVDC lines. 5l)The Heavy duty adopter as claimed in claim 1 houses a three position rotary switch marked LOW, NORMAL, HIGH depending on the length of the line and its noise, the power is set of either one of the three positions mentioned above. 52) The Heavy duty adopter as claimed in claim 1 houses a transmit meter which indicates the transmission of energy from the equipment to the HVDC line. 53)The power simulator and power supply unit as claimed in claim 1 is provided for in-house testing of the system before connecting the entire system to the HVDC transmission lines. The Powe line Fault locator unit, the Power line signature analyser unit, the Heavy duty adopter unit and the Power supply cum digital simulator unit as described in the complete specification and as herein described with reference to accompanying sketches and charts.

Full Text

FAULT LOCATOR AND ANALYSER EQUIPMENT FOR HVDC
LINES
The invention is the equipment LINE FAULT LOCATOR SYSTEM FOR HVDC POWER TRANSMISSION lines, is meant for testing and detecting fault location and preventive maintenance of, long HDVC transmission lines with length upto 2000km* It can detect the various kinds of developed and developing faults along the length of HVDC transmission line.
The equipment consists of 2 parts:
LFault locator part of the system:
This part of the system is used when a particular HVDC line being tested has tripped due to a fault. This part of the system detects the distance of fault from the point of testing in kilometers in the LCD display (Refer sl.no. 6/SKETCH 1). It also indicates the nature of fault, (i.e) OPEN type or SHORT type of fault, by operating the switch FAULT TYPE (Refer sl.no.3/SKETCH 1).
2.The Analyser part of the system:
The Analyser unit when connected to the HVDC lines gives all the various developing faults along the length of the line in kilometers, in the form of a hard copy print out. There are four formats of print outs representing these various kinds of faults in a variety of user friendly formats. It is also possible to monitor the condition of the line, dynamically by means of the provided graphic LCD display module. Since this part of the system is used for preventive maintenance of HVDC lines it is used generally when the line is healthy. This instrument also gives the degree of damage in 9 discrete levels (0 to 8). This degree of damage helps in giving priorities during maintenance. It is possible to decide on the points of fault which have to be repaired before going to other points of smaller faults.
This system is a comprehensive testing instrument for faults on HVDC lines with which it is possible to detect faults on occurrence of a fault and to as well maintain the line during maintenance to prevent occurrence of failure faults, thereby improving the reliability, availability and performance of the HVDC lines avoiding sporadic failures and saving lot of revenue by reducing the number of hours of outages.

EXISTING EQUIPMENTS AND THEIR DISADVANTAGES
The invention is for overcoming the problems and disadvantages of the existing in the method of fault location and fault analysis on HVDC lines. A study on the various types of faults that can occur on the HVDC lines was made. Having been arrived at the list of faults that can occur on HVDC lines, it was analysed that which of these faults could not be detected with the existing system . Hence we arrived at the list of faults that the existing system could not detect.
The list of faults are:
1. Open circuit fault
2. Pole to earth fault
3. Resistive contact jumper
4. Decapping fault
5. Low insulation of insulators
6. Outside object coming in close vicinity to the conductor
7. Earth wire hanging close to the conductor
8. Lightning arrestor failure
9. Failure of PLCC capacitor and other filter capacitor which are connected across the line.
10. conductor oversagging
11. High induction from the adjacent charged multicircuit lines.
12. Fault on spur lines to the main line.
The existing systems were generally of the type that are connected permanently to the HVDC lines . They came into operation only after the fault had occurred and the line had tripped due to the fault. And these indicated only some of the dead faults such as pole to earth . But practically they were found to be poor in accuracy and fault finding involved rigorous patrolling of the line. Further once a line had tripped and rectified(the fault at that point) there was no means for rechecking the fault without charging the line(faults occurred in any other points could not be checked by the existing system).But it is a known fact that charging a faulty line is dangerous for both the system as well as the HVDC line connected to it. As it caused a lot more damage than the fault itself.

Secondly it is not possible again to check the line after rectification of the fault for proper repair and to determine whether there are no multiple faults on the line other than the one rectified. Finally these ONLINE systems are only for fault detection after occurrence of a fault. They give no data on the presence of other developing faults on the line. Hence it is not possible to undertake preventive maintenance on these lines with these types of fault locators. These ONLINE fault locators have not been able to find all the kinds of faults highlighted above making them non-comprehensive tool for fault location and detection of developed and developing faults on HVDC lines. Moreover, the existing system is laborious, time consuming and not cost effective.

THE INVENTION
The object of this invention is to detect the faults that may occur on the HVDC lines* The faults that may occur may be categorized into 12 types of faults.
1) Conductor snapping and falling on the ground
2) Jumper Snapping

3) Insulator Decapping
4) Low Insulation of Insulators

5) Lightening Arrestor Failure
6) PLCC Capacitor Failure
7) Conductor Sagging
7) Resistive Contact for Jumper
9) Outside object coming in contact or very near vicinity of the line
10) Earth Wire close to the conductors
11) High Induction from adjacent charged Multi circuit line 12) Fault on Sour Lines to the main line

STATEMENT OF INVENTION
The equipment thus invented has the following technical features.
1. The equipment is capable of detecting faults on line with length up to 2000km.
2. The equipment is capable of detecting all kinds of dead faults which cause the line to trip., such as

1. OPEN CIRCUIT
2. POLE TO EARTH
3. DECAPPING
4. LOW INSULATION OF INSULATORS
5. LIGHTINING ARRESTOR FAILURE
6. PLCC CAPACITOR OR CVT FAILURE
7. CONDUCTORS OVER SAGGING
8. RESISTIVE CONTACT OF JUMPER
9. OUTSIDE OBJECT COMING IN CONTACT OR CLOSE VICINITY OF CONDUCTOR
10. EARTH WIRE SAGGING CLOSE TO CONDUCTOR
11. FAULTS ON BOTH SPUR LINE AND MAIN LINE IN CASE OF LINES WITH SPUR LINES.
12. JUMPER SNAPPIING

3. The equipment is capable of withstanding heavy induction present on the line being tested.
4. The transmitter has enough power to transmit its power along entire length of the line has suitable amplitude so as to be able to highlight all the developing and developed faults on the line.
5. The equipment is capable of suppressing the switching HVDC noise present on the HVDC LINE.
6. The equipment is capable of detecting all the faults on the HVDC line up to a length of 2000km with a resolution of 100 meters.
7. The equipment is capable of giving the fault distance on a graphic LCD screen directly in kilometers.

LINE FAULT LOCATOR SYSTEM FOR HVDC POWER
TRANSMISSION LINES
The equipment consists of four units:
1. POWER LINE FAULT LOCATOR UNIT HD-1720-APEX-D HVDC-1720-film
2. POWER LINE SIGNATURE ANALYSER UNIT HD-1720-APEX-D
HVDC-1720-sam
3. HEAVY DUTY ADOPTER UNIT HD-1720-APEX-D HVDC-1720-adm
4. POWER SUPPLY CUM DIGITAL SIMULATOR UNIT HD-1720-APEX-D

POWER LINE FAULT LOCATOR UNIT:
This equipment along with the Heavy duty Adopter and Power supply unit when connected to de-energized power line can indicate faults such as OPEN CIRCUIT or SHORT CIRCUIT at any point up to 2000KM long transmission line.
These unit controls the Adopter who is connected in tandem to transmit lOkilo volts and 500 kilowatts of power pumped in to DC transmission line to detect faults up to 2000 km. The fault locator equipment is equipped to indicate any of the types of faults namely, open circuit, pole to earth and decapping and the distance at which the fault has occurred from the testing end.
POWER LINE SIGNATURE ANALYSER UNIT:
This equipment houses a graphic LCD display. This equipment when connected in tandem with Adopter to the power line gives the signature (that is the characteristic of the line) of the entire length of the line with 100 meter resolution.
It gives four print outs such as
1. Highlights of fault indication in KM
2. Signature of the entire length of the line in 0.1km resolution
3. Scan print out of the entire length of the line with the lOOmetre resolution.
4. The map of the homogeneity of the line in 9 discrete vertical steps (0 to 8) Indicating the non-homogeneity of the line.
The equipment has got all facilities to analyse the entire function of signature analysis.
An output is provided for printer connection and another output is provided for computer interface.
Dedicated computer software is provided to load the signature of the line and analyse all aspects regarding the non-homogeneity of the line.
It is also possible to view the signature of the line dynamically in the graphic LCD display.

HEAVY DUTY ADOPTER UNIT:
This equipment is connected in between fault locator or analyser and transmission line. This equipment houses the transmitter and line matching unit and it also houses the filters to suppress HVDC switching noise namely, electrical switching noise. It produces enough power to illuminate a 2000km transmission line to get return which are above noise level to the sending end, for which the Adopter has all necessary controls.
POWER SUPPLY CUM DIGITAL SIMULATOR UNIT:
This unit houses a maintenance free battery and necessary charging unit from mains. It has in -built simulator for in house testing of the Fault locator unit and the Analyser unit.

POWER LINE FAULT LOCATOR UNIT: (SKETCH 1)
The Powerline fault locator unit consists of the following controls:
1. SET POWER:
(REFER SL. NO. 1)
This consists of a rotating switch, which can be set in three positions. Namely
1. LOW POSITION
2. NORMAL POSITION
3. HIGH POSITION
The respective positions are selected depending on the length of the HVDC line required to be tested for finding the fault. By keeping the control in LOW position it is possible to test the faults occurring at any point within 100 km s of the line. For testing the faults between l00 kms and 2000 kms on the HVDC lines the NORMAL or HIGH position is selected.
2. POWER ON:
(REFER SL. No.2)
The function of this switch is as follows.
This switch when put to 'ON' position switches on the power to the equipment. The power to this equipment is got from a 12 volts 26 Ah dry fit maintenance free battery housed in the POWER SUPPLY/SIMULATOR UNIT.
This 12 volts got from the POWER SUPPLY/ SIMULATOR UNIT is connected to the Fault locator unit through the power switch. In the Fault locator unit this 12 volts is converted to suitable voltages necessary to operate the system. This 12 volts is got in to the Fault locator unit from the 12 pin connector present on the Fault locator unit (Reference No. 9 in the figure.)

3. FAULT TYPE
(REFER SL. NO. 3)
This is an important part of the invention. By operating this it is possible to ascertain the type of faults that has occurred on the HVDC lines.
This is a rotating switch having three positions marked
1. SET
2. OPEN
3. SHORT
In SET position it is possible to ascertain the distance of fault. From the OPEN and
SHORT position of the switch it is possible to ascertain whether the fault that has
occurred is of OPEN type such as
JUMPER OPEN, (dead fault)
CONDUCTOR CUT (dead fault)
LOOSE JUMPERS,
DECAPPING OPEN VARIETY AND RESISTIVE CONTACT OF JUMPER
or SHORT type such as
POLE TO EARTH FAULT,
DECAPPING SHORT VARIETY,
EARTH WIRE HANGING CLOSE TO CONDUCTOR,
LIGHTINING ARRESTOR FAILURE,
COUPLING CAPAPCITOR FAILURE,
OUTSIDE OBJECT COMING CLOSE TO VICINITY OF THE CONDUCTOR,
LOW INSULATION OF INSUALTORS,
AND CONDUCTOR SAGGING.
If the fault distance appearing in SET position continues to appear in OPEN position and does not appear in SHORT position then the fault is termed as OPEN type of fault. It could be due to one of the above mentioned types of faults under OPEN category.
If the fault distance appearing in SET position continues to appear in SHORT position and does not appear in OPEN position then the fault is termed as SHORT type of fault. It could be due to one of the above mentioned types of faults under SHORT category.

4. SET FAULT:
(REFER SL. NO. 4)
This is one of the most important and crucial aspects of the invention. A fault may occur at any point in the entire length of 2000km of the HVDC lines. The invention enables to fix the point of fault with accurate precision using the SET fault, so that the remedial measures can be taken at the point where the fault has occurred. The invention not only enables to fix the point of fault but also enables the same to be carried out in seconds, thus saving valuable time which is crucial when a fault occurs in the lines. It not only saves time but also saves lot of revenue in crores of rupees to the electrical utility.
The SET FAULT is a ten turn potentiometer. The invention also includes a switch which can be set to LOW or HIGH position, while using the SET FAULT. Normally the SET FAULT is operated by keeping the switch in LOW position. If no reading appears on the LCD display (REFER SL. NO. 6).THIS ITSELF IS AN INVENTIONthe switch is changed to HIGH position. As the SET fault is turned in the clockwise direction the reading will appear on the LCD display to indicate at what point or distance of line the fault has occurred. For example, if a fault has occurred at a point, which is 100.1 km from the starting point of the line, this is indicated in the LCD display. This figure will not change even if the SET FAULT is rotated further; thus it is possible to find the place of fault on the lines with absolute precision. This operation is not only accurate but also is easy to operate by even laymen. Once the place of fault is known as indicated in the LCD display, remedial measures will be taken without loss of time. Thus the invention is accurate, time and revenue saving and easy to operate and depending on the type of fault it also helps to save precious life of human beings or cattle which may be affected by fault occurring in the HVDC lines. The fault as seen on the LCD display can be noted down for future use.
SET FAULT can also be used while using the SIMULATOR for in-house testing. The SET FAULT has two more features namely OVERSET and FAULT SET. If the SET FAULT is not operated properly the OVERSET will glow to indicate the same. The FAULT SET will start glowing to indicate that the point of fault is about to be displayed and thus the operator is alerted.
5a) SET BLANKING;
(REFER SL.NO. 5)
The SET BLANKING is another innovative aspect of the invention. By using this it is possible to detect the fault at any desired length of the HVDC line and blank the

length of the line where there is no need for the test of the faults. This is further explained as follows.
The HVDC lines runs through thousands of kms from the starting point to the end point. In case the line develops multiple faults along its length without the above feature it is only possible to see one fault, that is, the first fault the closest fault to the testing point. It might not be possible to see beyond this fault for multiple faults. So by having this feature it is possible to blank this fault reading to search for multiple faults on the line.
For example, say we are testing a line of length 1500kms. Suppose a fault reading of 100 kms appears in the FAULT LOCATOR. It is not possible to test the line from 100 kms to 1500 kms for faults. So by blanking the reading of 100 kms by using the ten turn blanking potentiometer and selecting the corresponding position on the BLANKING DISTANCE switch (REFER SL. NO.7) it is possible to blank the distance of 100 kms and check for other faults from lOOkms to 1500kms. Further this blanking facility is very useful for lines having spur line to the main line(that is T-offs)
5b) SCAN ON/OFF
This switch helps in scanning every 3 kms of the line, in the LCD DISPLAY.
6) 41/2 DIGIT LCD DISPLAY
This LCD display displays the fault distance in kms.
7) BLANKING DISTANCE:
This switch is a 6-position switch marked 0km, 400km, 800km, 1200km, 1600km and 2000km. Each position indicates the starting distance of blanking and further 400 km of blanking is got from the SET BLANKING POT.
8) POWER:
This switches on power to the instrument on connecting the 12 pin output connector to either the power supply/simulator unit's 12 pin connector for simulated testing or by connecting it to the adopter's unit 12 pin connector and connecting the power supply simulator unit's 5 pin pig tail connector to the adopter unit's 5 pin connector for testing HVDC lines.
9) TO ADOPTER:
This 12 pin connector is connected to the 12 pin socket on the POWER SUPPLY/SIMULATOR unit for simulated testing. This 12 pin connector is connected to the 12 pin connector socket on the adopter for testing HVDC lines.

TESTING OF SPUR LINES
For testing lines with spur lines it is necessary to have previous healthy line results. For a healthy line the readings indicated by the Fault locator are
1. Joint of Spur to the main line
2. Spur line end
3. Main line end
So, to test a spur line, it is necessary to have the above three readings of the line, when the line is healthy.
For example,
Consider a line of length 40 km having a spur of 10 km at a distance of 20 km on the main line.

Now consider the above line during healthy conditions.
Now to test this line, keep the Set power switch in normal position, Set Fault pot fully anti clockwise position and Set fault switch in LOW position. Select ON position in the POWER switch (reference No. 8). Put the Blanking ON/OFF Switch to ON position. Set the ten turns Blanking pot too fully anti clockwise position. Now increase the SET FAULT pot, so as to get the point of Spur joint in the display. To get this reading the Fault set pot has to be set to a level higher than that normally required. Next turn the ten turn Blanking pot in the clockwise direction until the above reading just disappears from the display. Further, set the Fault set pot to get the next closer reading, that being the Spur line end, that is, 20 km + 10 km = 30 km. This indicates that the fault has occurred at the spur end.
Now turn the ten turn Blanking pot further, to remove the above reading of 30 km. Then set the Fault set pot to get the next higher reading of 40 km, which is the end of the Main line. Note the above three readings for future reference.

NOTE:
Spur joint reading always appears in short position of the Fault type switch. Whereas the Main line end and Spur line end appear in either open or short position, depending on the type of end termination.
POSSIBILITIES OF FAULTS ON SPUR LINES:
There are three points on a spur line where faults could occur.
1. Between testing end and spur joint
2. Between spur joint and Main end
3. Between the spur joint and spur end
Testing case 1 type of faults:
For faults between testing end and spur joint the fault distance is directly got on the display as the first result and with further Blanking it will not be possible to get the spur joint, spur line end and main line end readings.
Testing case 2 type of faults:
The faults between the spur joint and Main end, following the above procedure, first the spur joint is got. After Blanking the spur joint the spur end is got. After Blanking the spur end the fault point is got and it is not possible to get the main end
Testing case 3 type of faults:
For faults between the spur joint and spur end, following the above procedure, first the spur joint is got. After Blanking the spur joint the point of fault is got. After Blanking the point of fault the main line end is got, indicating that the fault is between the spur joint and spur end.

FINDING DECAPPING FAULTS IN POWER LINES
The line fault locator may be used to find decapping faults in transmission lines, where the line is hanging in the air without touching ground.
PROCEDURE
Now connect the fault locator to the lines as indicated previously
Now get the fault readings of the line. If the fault locator under normal setting shows the end of the line then it is presumed that line conductor is upto the end and it is not snapped any where or it is not touching earth any where .Then it could be presumed that a decapping fault may exist on the lines. First get the end reading of the line by turning the Fault set pot in the clockwise direction. Now after getting the end reading turn the Fault set pot further from the previous setting to see if any other readings other than the end of the line appears. If any reading do appear note these readings, then this may be a decapping fault. This fault distance could appear either in short or open positions of the fault locator depending on the nature of decapping.

POWER LINE SIGNATURE ANALYSER (SKETCH 2)
1. POWER ON:
This switches on the power to the equipment, when the 12 pin connector on the analyser is connected to either the adopter for testing of the HVDC lines or to the 12 pin connector on the power supply or simulator unit for testing in-house.
2a. MODE FIXED/DELAYED: This toggle switch is used to select whether we want the signature of a particular length of the line(DELAYED) or the full length of the line(FIXED).
2b. INITIAL DELAY: This facility is provided so that any part of the line could be moved in to the center of the LINE VISION DISPLAY(SL.NO. 2) and viewed dynamically and with better resolution.
2c. SET: This INITIAL DELAY is achieved by this 10 turn potentiometer and a six position switch marked 0 km to 1600 km. When the line length to be viewed is between 400km to 800km then the SET has to be kept in 400km. If the line length to be viewed is 1200km to 1600km then the SET has to be kept in 1200km. Hence this enables the viewing of every 400km of the line in the display. This choice of the length being selected for viewing in the LINE VISION DISPLAY is displayed in a 41/2 digit LCD display (SL.NO. 3) for better clarity.
3a. SET GAIN: This potentiometer is slowly turned in clockwise direction to get the fault readings on the display.
3b. AUTO/MANUAL: If MANUAL is selected and the SET GAIN pot is set so as to set the reflection from the end of the line to view in full screen on the display.
3c. AUTO GAIN: If AUTO is selected in the AUTO/MANUAL switch the AUTO GAIN switch is put to one of the 6 positions marked 1 to 6 (six positions denotes the level of clarity of the signature in the chronological order), the line is viewed in the full screen on the display.
This selection helps in comparitive study of the developing faults on the line. For
example, if we take a signature today and take another signature a month later, it is
possible to take both the signature with the same gain settings. That is, position 1 to
6.
Taking signature in same settings helps in determining whether a developing faults
on the line has increased in level from its previous value.
For example, we take signature of a line today with Auto gain switch in 5th position.
After a month we take the signature of the same line with Auto gain switch in 5th
position. We will be able to determine which point on the line has increased in fault
level and whether any other new points have appeared further to the existing faults.

3d. PRINTER ON:
This switch when put in ON position, switches on power to the printer through the printer chord pig tail provided.
4. PRINT/DISPLAY:
This switch when put in "PRINT" position enables to take the printouts and when put in "DISPLAY" position enables to view in the display.
5. RESET:
This is used to reset the system for proper operation.
6. LCD DISPLAY:
This is LCD display which displays the line dynamically and graphically.
7. TRASMIT AND STORE:
After connecting the Heavy Duty Adopter unit to the HVDC lines and connecting the Line Vision Signature Analyser unit to the Adopter unit, Pressing this button will load the reflected pulses received from the line to the Line Vision Signature Analyser unit.
8. HIGHLIGHTS:
Pressing this highlight switch will give the print out of all the developing / developed points of faults in kilometers along with the degree of fault.(This switch should be pressed only after connecting the Printer cable and the printer power chord to the printer and switching on the PRINTERJ3N/OFF (Refer Sl.No. 3d/ SKETCH 2) switch to ON position)
9. SIGNATURE:
By connecting the printer and pressing the switch will give corresponding print of the SIGNATURE on the printer.
10. SCAN:
By connecting the printer and pressing the switch will give corresponding print of the SCAN on the printer.
11. MAP:
By connecting the printer and pressing the switch will give corresponding print of the MAP on the printer.

12. STORE:
By connecting the laptop computer's Parallel port to the printer cable and pressing this switch will store the data to the computer.
13. PRINT DISTANCE SELECT:
This is a 6 position rotary switch marked 0km,200km,400km, 800km, 1200km, 1600km. Depending on the line length this switch is selected so as to save the stationary while printing.
14. CONTRAST:
This is used to set the contrast of the LCD DISPLAY.
15: TO ADOPTER UNIT:
This is a 12 pin connector, connected to the Adopter unit with the cable provided for testing HVDC lines.

HEAVY DUTY ADOPTER UNIT (SKETCH 3)
Since the transmission lines are tested for faults offline it is necessary to illuminate the lines for two purposes. They are as follows,
1. to locate the fault by using the Power line Fault locator unit,
2. to ascertain the signature (the characteristics of the line) using the Power line
signature Analyser unit.
The Adopter unit is connected between
The Fault locator unit and the transmission line
Or
The Line Vision Signature Analyser unit and the transmission line
This equipment houses the transmitter and the line matching unit.
The function of this unit is fourfold
1. This unit suppresses the induction( the voltage produced in the line due to the power flowing in the adjacent lines) so that safe working of the personnel using the equipment is ensured.
2. Generates the signal necessary to illuminate the line and to get back the reflections and give these signals got from the line to the Fault locator unit or analyser unit for processing.
3. The Alter in this equipment suppresses the switching noise of the HVDC lines.( as DC is converted to AC it generates a noise which creates disturbance in the transmission lines). This disturbance is overcome by the Adopter unit.
4. It also matches the transmitter to the impedance (this is the line characteristics impedance) of the line.
This unit produces enough power that illuminates a 2000 km transmission line and gets back the pulses from the line.
The various controls that are provided in this equipment and their working are as follows
• 5 PIN POWER SUPPLY CONNECTOR (REFER SL. NO. 1)
This is located on the left hand top corner of the unit. The pigtail 5 pin connector of the Power supply cum simulator (refer sketch no. 4) unit is connected to this 5 pin socket.

• FILTER ON/OFF( REFER SL.NO 2 )
This is switched to "ON" position when the lines are long and noisy, i.e the disturbance caused by other transmission lines or due to other causes.
• 12 PIN SOCKET CONNECTER ( REFER SL. NO. 3)
This is located on the left bottom corner of the unit. This is connected either to the fault locator or the analyser units 12 pin connector
• SET POWER (REFER SL. NO. 4)
This supplies power on the lines and is three position rotary switch market
1. Low
2. Normal
3. High
Depending on the length of the line or the level of the noise the power is set by keeping the position in low or normal or high position.
• INDUCED VOLTAGE METER( REFER SL NO 5)
This meter indicates the presence of induction on the HVDC lines
• EARTH (REFER SL NO 6)
There are earth terminals in the unit.
One is on the right bottom corner and the other is in the right side of the unit Both these terminals are connected to the good station earth with the earth cable and clamp provided before connecting the unit to the HVDC lines.
• 12 PIN CONNECTOR MOUNTED ON EPOXY GLASSf REFER SL NO. 7)
This is connected to the HVDC lines to be tested with connected cable and hook rods provided.
• TRANSMIT METER (REFER SL NO. 8)
This meter indicates the transmission of energy from the equipment to the HVDC lines

POWER SUPPLY AND SIMULATOR UNIT (SKETCH 4)
This equipment consists of a battery for supply of power to the lines to be tested and for the equipments used and a simulator for inhouse testing. The invention relating to these two parts and the working of the same are as follows.
1. MAINS ON:
This is used to switch on AC mains to the battery charger.
2. POWER ON:
This should be put on ON position for switching on power to the system.
3. SIMULATED DISTANCE:
This is a 3 position switch marked 200km, 800km and 1400km. Putting this switch to each of these positions generates a distance of 200km, 800km and 1400km(approx.).This is used for in-house testing of the system.
4. MCB:
This is a protective device used to protect the battery against short circuit. It should be always on ON position during operations.
5. TO FAULT LOCATOR/ANALYSER UNIT:
This 12 pin connector is connected to either Power line Fault locator unit or Power line signature Analyser unit for in-house simulator testing.
6. MAINS INPUT:
The mains 230 VOLTS 50 Hz AC mains to the batter charger.
7. BATTERY:
INDICATORS:
Charged:
This green LED always lights up when the 'POWER ON' SWITCH IS PUT TO 'ON' position indicating charged battery.

Discharged:
This red LED always lights up when the 'POWER ON' switch is put to 'ON' position indicating the battery is in discharged condition.
Charging:
This red LED lights up during charging of the battery and it gradually dims away on battery charging.
A FUSE OF 2 AMP IS ALSO PROVIDED for AC mains protection.
WORKING OF THE BATTERY:
The testing of the lines for faults is done offline. During the testing of fault in the lines the power has to be supplied to the equipment. This is being done by the battery. Provision is made to check whether the battery is fully charged before use. The 'MAINS ON1 switch switches on the AC mains to the battery charger. 'MAINS INPUT' socket is connected to a 230 volts 50 Hz AC mains(with the mains chord provided) for charging the battery.

WORKING OF THE INVENTION
Take the POWERLINE FAULT LOCATOR SYSTEM near the HVDC lines to be tested.
Now ground the HVDC lines with the EARTH GOS.
Select a good station ground. Take care to see that the grounding is proper.
Now connect the other end of the Grounding Clamp to the Heavy duty adopter's(SKETCH3)two Earth terminals(SLNo.6/SKETCH 3). Now connect the Heavy duty Adopter's 12 pin connector mounted on epoxy base( Sl.No.7) to the end of the hook sticks with a 12 pin plug provided. Connect the hook rod to the HVDC line.
Now interconnect the Power supply cum simulator unit(SKETCH 4) and the Heavy Duty Adopter unit with the 5 pin pigtail connector provided on the Power Supply cum Simulator unit.
Now connect the Power line Fault locator unit(SKETCH 1) with the Adopter unit with the 12 pin connector provided(Sl.No.9/SKETCH 1). Then make all initial settings on both the Adopter unit and the Power line Fault locator unit depending on the line length.
The initial settings of the Power line Fault locator unit are as follows.
i) SET POWER - NORMAL
ii) FAULT TYPE - SET
iii) ROTARY POWER SWITCH - ON
iv) BLANKING - OFF
v) SET FAULT POT - FULLY ANTI-CLOCKWISE
vi) GAIN LOW / HIGH - LOW
The initial settings of the Adopter (SKETCH 3) are as follows :-
i) POWER - Depending on line length.
ii) FILTER ON / OFF - ON
The initial settings of the Power supply cum Simulator unit (SKETCH 4) are
as follows :-
i) MCB -ON
ii) Power - ON
Now open the grounding of the HVDC LINE by opening the earth GOS.

Now switch the 'POWER ON' switch in the Powerline Fault locator to 'ON Position'.
Now turn the SET FAULT pot so as to get a reading in the 41/2 digit LCD display such that the reading in the display changes from 1888.8 to a fixed reading.
Note the reading. Similarly put the SET Fault switch to 'Open' and 'Short' positions and note the corresponding readings.
This distance is the distance of fault in a faulty line or is the length of line in a healthy line.
The type of fault is determined from the reading obtained in the OPEN & SHORT positions. If the reading in open position is same as SET position the fault is said to be OPEN CURCUIT fault or if it is otherwise it is said to be earth fault.
For connecting the Power line Signature Analyser (SKETCH 2) to the line, disconnect the connection between the Adopter and the Power line Fault locator unit at the fault locator end. Connect this 12 pin connector from the Adopter to the 12 pin connector (socket) on the Power line Signature Analyser (Sl.No. 15/SKETCH
2).
Now put the Analyser's (SKETCH 2) Print / Display switch (Sl.No. 4/SKETCH 2) to display mode. Select suitable button on the Analyser to match the end of the line so as to obtain the end of the line reflection in the display. Now select Manual / Auto switch Sl.No. 3b/Sketch 2) to 'Manual' position. Set the SET GAIN (Sl.No. 3a) pot from fully anticlockwise to clockwise so as to make the end of line reflection to just reach full screen.
Now put the PRINT / DISPLAY switch (Sl.No. 4) to 'Print' Position and press and release the 'RESET' (Sl.No. 5) button and then the Transmit / Store button( Sl.No.
7).
Now the line signature gets loaded into the Analyser and the end readings are displayed in Line vision display(Sl. No. 16).
Now use the other 4 buttons marked 'Highlights'(Sl.No. 8), 4Signature'(Sl.No.9), 'Scan'(SLNo.lO) & 'Map'(Sl.No. 11) buttons to get their corresponding prints on the printer.
Before getting printout it is necessary to connect the 2 pig tail cables from the Analyser to Printer Port Cable and Printer Power input to the printer. Then switch on the 'Printer On' switch in the Analyser to 'ON' position.
Connect the printer port cable to the computer parallel port using the cable provided and press COMPUTER STORE (Sl.No.12/SKETCH 2). Ten results are taken automatically from the Power line Signature Analyser unit and stored in the computer. The computer Software analyses these 10 sets of readings and gives out all the salient points on the line removing all other noise present on the line.

Explanation of the faults occurring on HDVC lines and how they are indicated by our instrument HT-1720-APEXD
I.OPEN CIRCUIT FAULT:
a) EXPLANATION OF THE FAULT:
In the case of open circuit faults the HDVC lines conductor cuts in the middle and hangs in the air without coming in contact with either the tower or the earth beneath .This can be of 2 types
1. Conductor cutting
2. Jumper snapping
1.Conductor cutting:
Due to various reasons the conductor itself can get cut. Thereby breaking the electrical path.
2 Jumper snapping:
Approximately for every kilometer a jumper is used to connect conductors along the length of the line. These jumpers are clamped at both ends to the conductor by means of clamps and bolts. In case any of these clamps or bolts give way they result in the jumper hanging in the air creating an open circuit fault.
b) INDICATIONS IN OUR INSTRUMENT:
Powerline Fault locator unit:
This instrument indicates the variety of fault as a distance in kms.
Example:-
LINE LENGTH - 100km
OPEN CIRCUIT - 35km
SET OPEN SHORT
35 35

In the above example the line is of length 100km with a fault of open circuit at 35 kms. The instrument Indicates the distance of fault in the SET position and the type of fault is determined depending on whether the reading corresponding to SET position appears in either OPEN or SHORT position. Since in the above example it appears in OPEN position the fault is said to be the OPEN CIRCUIT FAULT and at a distance of 35kms.
CONCLUSION:-
This kind of OPEN circuit fault can be detected by the fault locator part of instrument.
The example of the OPEN CIRCUIT FAULT when the line is connected to the POWER LINE SIGNATURE ANALYSER unit is as follows:
As explained earlier the Power line Signature Analyser gives the output in four formats.
1. HIGHLIGHTS:
This gives all the faulty points on the line as well as the end of the line with their degree of damage at that point of fault(in the line) in kilometers.
2. SCAN
This gives a raw printout of the signature of the line in numeric form. In this printout each " - " represents 100 meters. Hence each line of the printout represents 10 kms. Each point of fault is represented by a train of numbers(0 to 8). The point of fault is the centre of this train of numbers.
3. MAP
This is the graphical representation of the scan.
4. SIGNATURE
This is a sophisticated scan print. The point of fault is pinpointed in this format.

OPEN CIRCUIT FAULT:
Our transmission of pulse from the equipment is in the form of an inverted 'Y' This pulse travels along the length of the line and if it faces an open circuit during its travel along the length of the line it reflects back as a inverted 'Y' from the point of open circuit. This point of open circuit could either be the far end of the line kept open or dead open circuit fault along the length of the line. If the reflection is from the end of the line it is the distance in the highlights ,signature ,scan and map will be the length of the line, else, if it is a fault along the length of the line, then the distance indicated in the map, signature, scan, highlights will be equal to the distance of fault from the point of testing in kilometers.
EXAMPLE:
Let us consider a line of length 350km. Suppose the end of the line is kept open, then the output got from the signature analyser unit (that is signature, scan, highlights, map) will be as follows in the following pages. The end of the line is kept open and it is signified by an inverted Y. The line is healthy and we have the end of the line signifying open circuit.
REFER:
CHART 1 - MAP
CHART 2 - SCAN CHART 3 - SCAN
CHART 4 - HIGHLIGHTS
CHART 5 - SIGNATURE CHART 6 - SIGNATURE

SHORT CIRCUIT FAULT:
Our transmission of pulse from the equipment is in the form of an inverted 'Y'. This pulse travels along the length of the line and if it faces a SHORT circuit during its travel along the length of the line it reflects back as a 'Y' from the point of SHORT circuit. This point of SHORT circuit could either be the far end of the line kept short or short circuit fault along the length of the line. If the reflection is from the end of the line, it is the distance in the highlights, signature, scan and map will be the length of the line, else, if it is a fault along the length of the line, then the distance indicated in the map, signature, scan, highlights will be equal to the distance of fault from the point of testing in kilometers.
REFER:
CHART 7 - MAP
CHART 8 - SCAN CHART 9 - SCAN
CHART 10 - HIGHLIGHTS
CHART 11 - SIGNATURE CHART 12 - SIGNATURE

INSULATOR FAULT :
Since our pulse transmission is in the form of an inverted 'Y' any change in homogenity at any point along the length of the line depending on the impedance change can either be 'Y' or an inverted 'Y\ If the impedance at any point of reflection is lower than the characteristic impedance of the line then the reflection from that point will be in the form of a *Y' or if it is higher than the characteristic impedance then it is an inverted *YComing to insulators aspect it is found that in a string of insulators a few of insulators can develop low insulation causing power leaks at that point. This point of power leakage are detectable from our signature* The impedance change caused by these failed insulators is of very low values. These are detectable by the equipment only when we go to very high gain settings such as auto gain 5,6 ((3c) SKETCH 2) and it is found in most of the cases that these points appear as inverted *Y% i.e., open type. As they do not affect the characteristic impedance at that point, so as to bring it below the value of characteristic impedance of the line.
REFER AUTO GAIN 5 REFER AUTOGAIN 6
CHART 13-MAP CHART 19-MAP
CHART 14 - SCAN CHART 20-SCAN
CHART 15 - SCAN CHART 21-SCAN
CHART 16 - HIGHLIGHT CHART 22-HIGHLIGHT
CHART 17 - SIGNATURE CHART 23-SIGNATURE
CHART 18 - SIGNATURE CHART 24-SIGNATURE

CONCLUSION:
As the arm of the "Y" is pointing towards open side in the MAP, the distances of developing fault have to be taken from the open side in the Highlights. Hence, the points 40.8, 42.9 and 244.7 are the pints of developing fault, with degree of fault 3. The degree indicates the intensity of damage of the line at that point( If the damage is "8" it is presumed to be a dead fault).

OPEN CIRCUIT: LOOSE JUMPER
In case of a loose jumper the overall series resistance of the conductor increases at the point of loose jumper along the line. As our pulse travels along the length of the line and when it arrives at the point of loose jumper it faces a change in homogenity causing major part of the pulse to reflect back from that point. The remaining point of the pulse travels to the end of the line and gets reflected back from the end of the line. Since the pulse has weakened, the end reflection will be lower in level compared to that reflected from the point of loose jumper. This reflected pulse will be in the form of an inverted "Y".

TEST RESULT
Pole Open Highlights
2.8(8) 350.0(8)
Pole Short Highlights
0.6 (8) 348.1(8) 352.0(8)
Note:
The fault distance 350km in the Pole Open side indicates the open circuit fault.

TEST RESULT
Pole Open Highlights 2.5(8) 348.1(8) 352.1(8) Pole Short Highlights 0.6(8) 350.0(8)

TEST RESULT
Pole Open Highlights
1.5(8) 40.5(3) 143.0(3) 245.0(3) 350.0(8)
Pole Short Highlights
0.5(8) 41.4(3) 044.2(3) 141.5(3) 144.6(3) 243.5(3) 246.5(3) 348.5(8)
351.5(8)

TEST RESULT
POLE OPEN
30KM
40KM
—3 50KM
60KM
100KM
10KM
80KM
90KM
200KM
30KM
3 50KM
80KM
300KM
40KM
60KM
70KM
80KM
90KM
400KM

TEST RESULT
POLE SHORT
—8 10KM
40KM
3 3 50KM
60KM
70KM
80KM
90KM
100KM
10KM
20KM
30KM
40KM
90KM
200KM
3 3 50KM
60KM
70KM
300KM
10KM
20KM
30KM
40KM
8 . 60KM
70KM
80KM
90KM
400KM

TEST RESULT Pole Open Highlights 1.5(8) 040.5(5) 143(5) 245(5) 350(8) Pole Short Highlights
0.5(8) 41.4(5) 044.2(5) 141.5(5) 144.6(5) 243.5(5) 246.5(5) 348.5(8) 351.5(7)

TEST RESULT
Pole open highlights
2.7(8) 236.6(7) 348.6(6)
Pole short highlights
0.7(8) 234.5(7) 239.3(6) 345.6(6) 351.5(7)

CLAIMS
1) A Power line fault locator system comprising
i) Power line fault locator unit
ii) Power line signature analyser unit
iii) Heavy duty adopter unit
iv) Power supply cum digital simulator unit
is capable of detecting and locating the various types of faults offline, such as herein described on HVDC transmission line upto the distance of 2000kms with a resolution of 100m, further the said system is capable of simultaneously detecting ,locating and identifying the multiple faults, if any on HVDC transmission line(s).
2) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the conductor snapping and falling on the ground.
3) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the conductor snapping.
4) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating insulator decapping.
5) A Power line fault locator system as claimed in claim 1 wherein the said system is capable of detecting and locating the fault of low insulation of insulators
6)A Power line fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the lightening arrester failure.
7) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the PLCC capacitor failure.
8) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the conductor sagging
9) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the failure of resistive contact of jumper.
10) A Power line Fault locator system as claimed in claim 1 where in the said system
is capable of identifying and locating any outside /foreign body /object coming in
contact or very near vicinity of the line

11) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating the earth wire portion coming close to the conductors*
12) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of working under high induction from adjacent charged multi circuit transmission lines and other line crossings.
13) A Power line Fault locator system as claimed in claim 1 where in the said system is capable of identifying and locating faults both on the main line as well as on the spur lines in case of lines with spur lines.
14) The Power line fault locator unit as claimed in claim 1 along with the heavy adopter and power supply unit is capable of indicating the faults such as open circuit or short circuit at any point up to the 2000km long transmission line when connected to deenergised power line.
15) The Power line signature analyser unit as claimed in claim 1 houses a LCD display and when connected in tandem with adopter to the power line gives the signature (the characteristic of the line) of the entire length of the line with the 100m resolution.
16) The Heavy duty adopter unit as claimed in claim 1 is connected in between fault locator or analyser and transmission line and further houses the transmitter and line matching unit and Alters to suppress HVDC switching noise and any other 50hz induction present on the line.

17) The Power supply cum digital simulator unit as claimed in claim 1 further houses a maintenance free battery and necessary charging unit from mains and an in-built digital simulator for in-house testing of the fault locator unit and analyser unit.
18) A method of detecting, locating and identifying the nature of the fault(s) on HVDC transmission line upto the distance of 2000km with a resolution of 100m by operating a line fault locator system as claimed in claim 1.
19) The method as claimed in claim 18 wherein a rotating switch of the power line fault locator unit can be set either in low position or normal position or high position.
20) The method as claimed in claim 18 wherein the detecting and locating the fault at any point within 100km of the line by setting the rotating switch of claim 19 at low position.

21)The method as claimed in claim 18 wherein the detecting and locating the fault at any point from 100km to 2000km on the HVDC lines by setting the rotating switch of claim 19 either in normal or high positions.
22) The method as claimed in claim18 wherein the fault type is ascertained by operation of another rotating switch having three positions marked as SET, OPEN and SHORT.
23) The method as claimed in claim 18 wherein the open type fault appears only in open position at a fault distance appearing in SET position and does not appear in SHORT position.
24) The method as claimed in claim 18 wherein the SHORT type fault appears only in SHORT position at a fault distance appearing in SET position and does not appear in OPEN position.
25) The method as claimed in claiml8 wherein a switch SCAN ON/OFF is operated to check for faults in the HVDC transmission lines by moving a window equal to 3km along the entire length of the line continuously with the help of the set blanking potentiometer controL(ref.s.l.no.5a/sketch I)
26) The method as claimed in claimlS wherein a LED lamp, OVERSET is provided to indicate the setting of the SET FAULT potentiometer beyond the minimum required threshold level.
27) The method as claimed in claiml8 wherein a 4 l/2digit LCD 7 segment numeric display is provided by means of which it is possible to get directly the distance of faults in kms directly.
28) The method as claimed in claim from 18 to 27 wherein for the detecting and locating the multiple faults , situated or located at various positions throughout the length of HVDC transmission line(s) by using SET BLANKING technique.
29) The rotating switch of claim 22 when placed at SET position, it ascertains the distance of the fault.
30) The rotating switch of claim 22 when placed at OPEN position, ascertains whether the fault that has occurred is of open type such as jumper open (dead fault), conductor cut (dead fault), loose jumpers ,de-capping open variety, resistive contact of jumper and like.
31) The rotating switch of claim 22 when placed at SHORT position ascertains whether the fault that has occurred is of short type such as pole to earth fault, decapping short variety, earth wire hanging close to conductor, lightning arrestor failure, coupling capacitor failure , outside object coming close to the vicinity of the conductor, low insulation of insulators, conductor sagging and like.

32) The Power line signature unit as claimed in claim 1 houses a LCD display displaying various faults on the line in graphical and dynamic form on the display.
33)The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the HIGHLIGHT switch will give highlight printout of all the developing /developed points of faults in kilometers along with the degree of fault.
34) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the SIGNATURE switch gives the print out of signature which will give the signature point of all the developing/developed points of faults in kilometers along with the degree of fault.
35) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the SCAN switch which will give the scan printout of all the developing/developed points of faults in kilometers along with the degree of fault.
36) The Power line signature unit as claimed in claiml houses a switch namely PRINT/DISPLAY which when put in PRINT position and pressing the MAP switch which will give the map print out of all the developing/developed points of faults in kilometers along with the degree of fault.
37) The Power line signature analyser unit as claimed in claim 1 houses a switch namely COMPUTER STORE which on pressing will load 10 samples of line data from the analyser unit to the computer for complete analysis of the line.
38) The Power line signature analyser unit as claimed in claim 1 when connected to a laptop computer interface can detect and locate all types of faults in the environment of heavy switching noise and any other noise present on the line using appropriate software.
39) The Power line signature unit as claimed in claiml houses a switch namely transmit store that will load the line signature to the equipment.

40) The Power line signature analyser unit as claimed in claiml does the process of transmitting high voltage power pulses on HDVC lines receiving the reflected pulse and processing them for detection of various developed and developing faults.
41) The Power line signature analyser unit as claimed in claiml houses a switch AUTO/MANUAL which when kept in MANUAL position and with a 10 turn potentiometer with turn indicator it is possible to ascertain the various developing faults along the length of the line with their degree of damage (i.e) with the marker on the potentiometer set to various positions starting from 1 to 10 positions upto 10 turns. It is possible to ascertain all the faults starting from the highest degree to the lowest degree and it is also possible to periodically ascertain the increase in degree of fault at various points along the length of the line with similar settings of the 10 turn potentiometer.
42) The Power line signature analyser unit as claimed in claiml houses a switch AUTO/MANUAL, which when kept in AUTO position, it is possible to ascertain the various developing faults along the length of the line with their degree of damage, when it is set to various positions from 1 to 6. It is possible to ascertain all the faults starting from the highest degree to the lowest degree and it is also possible to periodically ascertain the increase degree of fault at various points along the length of the line with similar setting of the switch.
43) The Power line signature analyser unit as claimed in claiml has DISPLAY mode switch which enables the graphical viewing of the lines in dynamic form. In this mode it is possible to see fixed lengths of line in case of lines upto length of 2000km in 5 steps. The steps being

1) 0km to 400km
2) 400km to 800km
3) 800km to 1200km
4) 1200km to 1600km
5) 1600km to 2000km
This is in the flxed mode of operation.
44) The Power line signature unit as claimed in claim 1 has DELAY mode
of operation it is possible to bring only part of the line to the center of the
display. This is achieved by means of lOturn potentiometer marked SET and switch

FIXED/DELAY mode. The switch has 6 positions marked 0,400,800,1200,1600,2000 and the lOturn potentiometer marked SET gives maximum delay of 4S0km.
49)The Heavy duty adopter unit as claimed in claim 1 houses a filter ON/OFF switch which when kept in ON position filters the noise when the lines are noisy and long,
50)The Heavy duty adopter unit as claimed in claim 1 indicates the presence of induction on HVDC lines.
5l)The Heavy duty adopter as claimed in claim 1 houses a three position rotary switch marked LOW, NORMAL, HIGH depending on the length of the line and its noise, the power is set of either one of the three positions mentioned above.
52) The Heavy duty adopter as claimed in claim 1 houses a transmit meter which indicates the transmission of energy from the equipment to the HVDC line.
53)The power simulator and power supply unit as claimed in claim 1 is provided for in-house testing of the system before connecting the entire system to the HVDC transmission lines.
The Powe line Fault locator unit, the Power line signature analyser unit, the Heavy duty adopter unit and the Power supply cum digital simulator unit as described in the complete specification and as herein described with reference to accompanying sketches and charts.

Documents:

594-che-2003 correspondence others 12-05-2011.pdf

594-che-2003 form-13 12-05-2011.pdf

594-che-2003-abstract.pdf

594-che-2003-claims.pdf

594-che-2003-correspondnece-others.pdf

594-che-2003-correspondnece-po.pdf

594-che-2003-description(complete).pdf

594-che-2003-description(provisional).pdf

594-che-2003-drawings.pdf

594-che-2003-form 1.pdf

594-che-2003-form 26.pdf

594-che-2003-form 4 pdf

594-che-2003-form 5.pdf

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Patent Number

219740

Indian Patent Application Number

594/CHE/2003

PG Journal Number

27/2008

Publication Date

04-Jul-2008

Grant Date

13-May-2008

Date of Filing

24-Jul-2003

Name of Patentee

MANDAYAM KRISHNAKUMAR SRINIVASAN

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	MANDAYAM KRISHNAKUMAR SRINIVASAN

PCT International Classification Number

H01H 83/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA