Title of Invention	AN ELECTRONIC SINGLE PHASE ENERGY METER
Abstract	The present invention relates to an electronic single phase energy meter comprising a terminal block (1) with terminals for connecting phase (2), neutral (3) and load (5), a shorting link (4) for isolation of phase during testing characterized in that a shunt resistor (6) is connected between the phase terminal (2) and one of the load terminals for sensing the load current, a current transformer (7) in which both the line from phase terminal (2) and the line returning to neutral terminal (3) are passed through the central portion as primary, for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit (9), the output from the summation circuit (9) and voltage between phase and neutral are connected to an energy measuring means (10) providing output signals for recording energy consumed and meter tampering.

Title of Invention

AN ELECTRONIC SINGLE PHASE ENERGY METER

Abstract

The present invention relates to an electronic single phase energy meter comprising a terminal block (1) with terminals for connecting phase (2), neutral (3) and load (5), a shorting link (4) for isolation of phase during testing characterized in that a shunt resistor (6) is connected between the phase terminal (2) and one of the load terminals for sensing the load current, a current transformer (7) in which both the line from phase terminal (2) and the line returning to neutral terminal (3) are passed through the central portion as primary, for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit (9), the output from the summation circuit (9) and voltage between phase and neutral are connected to an energy measuring means (10) providing output signals for recording energy consumed and meter tampering.

Full Text	The invention relates to electronic single phase energy meters with penalizing facility up to 100% in earth load tampered condition. Conventional electromechanical energy meters have wear and tear of parts built into it and hence the accuracy of reading deteriorate with ageing. They require frequent re-calibration and are prone to transit damage. They also require high starting current. The electromechanical meters do not show any reading if the load terminals and input terainals are interchanged. They also show nil reading when the phase and neutral are interchanged and the load is returned to local earth. Some of the above disadvantages are overcome by using elec¬tronic energy meters. The known electronic energy meters using current transformer as the sensing element can also be tampered at the consumer end to have meter reading lower than the actual consumption. This is done by connecting local earth to one end of the load instead of neutral, and interchanging the neutral and line at the input of the meter. The invention provides an electronic single phase energy meter, which will provide a reading of double the energy consumed if one end of the load is earthed, instead of connecting to neutral. If the neutral and phase at input are also interchanged, the meter will read the actual energy consumed. Thus if the consumer tampers with the meter connection, he may get penalized with charges up to 100% for the tampered energy and normal charges for the unhampered energy. Accordingly the present invention provides an electronic single phase energy meter comprising a terminal block with termi¬nals for connecting phase, neutral and load, a shorting link for isolation of phase during testing characterized by a shunt resistor connected between the phase terminal and one of the load terminals for sensing the load current, a current transformer in which both the line from phase terminal and the line returning to neutral terminal are passed through the central portion as prim¬ary for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit, the output from the summation circuit and voltage bet¬ween phase and neutral are being connected to an energy measuring means providing output signals for indicating energy consumed and meter tampering. The electronic single phase energy meter according to the invention records energy used even if the supply terminals and load terminals are interchanged or the neutral is replaced by using local earth. The invention will now be described in detail with reference to the accompanying drawings, in which Fig. it Shows the schematic diagram of the electronic single phase energy meter according to the invention. Fig. 2: Shows the wiring diagram of the energy meter under normal condition, phase neutral reversal condition, direction reversal condition and both phase-neutral and direction reversal condition. Fig. 3t Shows the wiring diagram of the energy meter under earth tampered condition, earth tampered with phase-neutra1 reversal condition, earth tampered with direction reversal condi¬tion and earth tampered with both direction and phase neutral reverse1 condition. The terminal block (1) is provided with input terminals for connecting phase (2) and neutral (3) and output terminals for connecting the load (5). The input terminal connected to phase is also connected to one of the output terminals through a hunt resistor (6). A current transformer (7) is provided with both phase line and neutral return passing through its central portion as primary. The voltage drop across the shunt resistor (6) and the current transformer output are fed to a summation circuit (9) to provide a voltage equivalent to the sum of the voltage drop across the shunt resistor (6) and the voltage across the second¬ary of the current transformer (7). The summation circuit (9) is known in the art and is a standard circuit used in devices. The output from the summation circuit (9) which is representative of the load current, and supply voltage between phase and neutral are fed to the energy measuring means (10). Preferably the supply voltage is attenuated by means of a voltage attenuator (6) before it is fed to the measuring means (10). Measuring means (10) is a standard measuring circuit for measuring electrical energy which provides an output signal with frequency proportion¬al to the energy consumed. The frequency of this output signal is counted using a frequency counter (11} preferably a digital frequency counter. The digital frequency counter output is displayed by means of an impulse counter (12) and the after constant is displayed on an LED (13). The measuring means (10) also provides the drive for LEO (14) for indicating direction reversal and LED display (15) for indicating earth tampering. The input to the measuring means (10) corresponding to the load current is the sum of the voltage drop across the shunt resistor (6) and current transformer output. The meter is con¬nected in normal condition as shown in Fig.2 condition 1. The phase is connected to terminal IS, neutral is connected to termi¬nal 25 and the load is connected between terminals 1L and 2L. In this condition, the current transformer output is zero since the voltage produced by the incoming current to the load gets nulli¬fied by the outgoing current through the neutral. Thus the electrical energy measured will be the actual energy consumed. In condition 2 shown in fig. 2, the phase and neutral arc inter¬changed. The meter according to the invention will still read the energy consumed by the load correctly, under this condition. In condition,3, shown in fig.2, the supply terminals and load terminals are interchanged and in condition 4, in fig. 2 in addition to interchanging the supply terminals and load termi¬nals, the phase and neutral are reversed. The meter according to the invention will read the energy consumed correctly. It will also be indicated by the LED display showing direction reversal. In condition 5 shown in fig. 5 one end of the load is earthed and the load is not returned to the neutral. In this condition the meter according to the invention will indicate twice the energy of actual consumption since the current trans¬former output is not nullified by the return current through the neutral. Thus the input to the measuring means (10) wil1 correspond to two times the current flowing through the load. This will result in penalizing the consumer 100% additional charge for the energy tampered and charging normal for the untam-pered energy. The LED display (15) will indicate earth tamper¬ing. In condition 8 shown in fig. 3 the neutral and phase con¬nections are interchanged and the load is returned to earth instead of neutral. The meter according to the invention will read the actual energy consumed under this condition. There will not be any voltage drop on the shunt resistance (6), But the output of the current transformer (7) will be in accordance with the energy consumed and this will be recorded by the meter. In condition 7 shown in fig. 3 the load is connected to supply terminals (IS and 2S) and the supply is connected to the load terminals (IL and 2L). The meter according to the invention will indicate twice the energy actually consumed. The voltage across the shunt resistor (6) will be added with the output of the current transformer (7) which will also be proportional to the energy consumed since the current transformer output will not be nullified when the load is not returned to the neutral. This will again result in penalizing the consumer with 100% more charges far the tampered energy and normal for unhampered energy. The LED display (14) and the LED display Thus the electronic single phase energy meter according to the invention will never show a reading less than the actual energy consumed in all possible type of tampering. It will penalize the tampering consumer by indicating double the tampered energy consumed under condition 9 and condition 7 shown in fig. 3. Such an energy meter can effectively deter tampering of the meter at the consumer end. WE CLAIM: 1. An electronic single phase energy meter comprising a terminal block (1) with terminals for connecting phase (2), neutral (3) and load (5), a shorting link (4) for isolation of phase during testing characterized in that a shunt resistor (6) is connected between the phase terminal (2) and one of the load terminals for sensing the load current, a current transformer (7) in which both the line from phase terminal (2) and the line returning to neutral terminal (3) are passed through the central portion as primary, for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit (9), the output from the summation circuit (9) and voltage between phase and neutral are connected to an energy measuring means (10) providing output signals for recording energy consumed and meter tampering. 2. The electronic single phase energy meter, as claimed in claim 1, wherein the voltage between phase and neutral is connected to the energy measuring means (10) through a voltage attenuator (B). 3. The electronic single phase energy meter, as claimed in claims 1 or 2, wherein the output signal from the energy measuring means (10) indicating the energy consumed is connected to a frequency counter (11) connected to impulse counter (12) for indicating energy consumed and an LED display (13) for indicating meter constant. 4. The electronic single phase energy meter, as claimed in any one of the previous clauns, wherein the output signals from the energy measuring means (10) indicating direction reversal and meter tampering are connected to direction reversal indicating display (14) and earth tamper indicating display (15) respectively. 5. The electronic single phase energy meter, as claimed in claim 3, wherein the frequency counter (11) is a digital counter. 6. The electronic single phase energy meter, as claimed in any one of the previous claims, wherein the terminal block (1) is provided with a shorting link (4) to isolate phase line from shunt resistor (6) during testing. 7. An electronic single phase energy meter, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Full Text

The invention relates to electronic single phase energy meters with penalizing facility up to 100% in earth load tampered condition.
Conventional electromechanical energy meters have wear and tear of parts built into it and hence the accuracy of reading deteriorate with ageing. They require frequent re-calibration and are prone to transit damage. They also require high starting current. The electromechanical meters do not show any reading if the load terminals and input terainals are interchanged. They also show nil reading when the phase and neutral are interchanged and the load is returned to local earth.
Some of the above disadvantages are overcome by using elec¬tronic energy meters. The known electronic energy meters using current transformer as the sensing element can also be tampered at the consumer end to have meter reading lower than the actual consumption. This is done by connecting local earth to one end of the load instead of neutral, and interchanging the neutral and line at the input of the meter.
The invention provides an electronic single phase energy meter, which will provide a reading of double the energy consumed if one end of the load is earthed, instead of connecting to neutral. If the neutral and phase at input are also interchanged, the meter will read the actual energy consumed. Thus if the consumer tampers with the meter connection, he may get penalized with charges up to 100% for the tampered energy and normal charges for the unhampered energy.

Accordingly the present invention provides an electronic single phase energy meter comprising a terminal block with termi¬nals for connecting phase, neutral and load, a shorting link for isolation of phase during testing characterized by a shunt resistor connected between the phase terminal and one of the load terminals for sensing the load current, a current transformer in which both the line from phase terminal and the line returning to neutral terminal are passed through the central portion as prim¬ary for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit, the output from the summation circuit and voltage bet¬ween phase and neutral are being connected to an energy measuring means providing output signals for indicating energy consumed and meter tampering.
The electronic single phase energy meter according to the
invention records energy used even if the supply terminals and
load terminals are interchanged or the neutral is replaced by
using local earth.
The invention will now be described in detail with reference to the accompanying drawings, in which
Fig. it Shows the schematic diagram of the electronic single phase energy meter according to the invention.

Fig. 2: Shows the wiring diagram of the energy meter under normal condition, phase neutral reversal condition, direction reversal condition and both phase-neutral and direction reversal condition.
Fig. 3t Shows the wiring diagram of the energy meter under earth tampered condition, earth tampered with phase-neutra1 reversal condition, earth tampered with direction reversal condi¬tion and earth tampered with both direction and phase neutral reverse1 condition.
The terminal block (1) is provided with input terminals for connecting phase (2) and neutral (3) and output terminals for connecting the load (5). The input terminal connected to phase is also connected to one of the output terminals through a hunt resistor (6). A current transformer (7) is provided with both phase line and neutral return passing through its central portion as primary. The voltage drop across the shunt resistor (6) and the current transformer output are fed to a summation circuit (9) to provide a voltage equivalent to the sum of the voltage drop across the shunt resistor (6) and the voltage across the second¬ary of the current transformer (7). The summation circuit (9) is known in the art and is a standard circuit used in devices. The output from the summation circuit (9) which is representative of the load current, and supply voltage between phase and neutral are fed to the energy measuring means (10). Preferably the supply voltage is attenuated by means of a voltage attenuator (6)

before it is fed to the measuring means (10). Measuring means (10) is a standard measuring circuit for measuring electrical energy which provides an output signal with frequency proportion¬al to the energy consumed. The frequency of this output signal is counted using a frequency counter (11} preferably a digital frequency counter. The digital frequency counter output is displayed by means of an impulse counter (12) and the after constant is displayed on an LED (13).
The measuring means (10) also provides the drive for LEO (14) for indicating direction reversal and LED display (15) for indicating earth tampering.
The input to the measuring means (10) corresponding to the load current is the sum of the voltage drop across the shunt resistor (6) and current transformer output. The meter is con¬nected in normal condition as shown in Fig.2 condition 1. The phase is connected to terminal IS, neutral is connected to termi¬nal 25 and the load is connected between terminals 1L and 2L. In this condition, the current transformer output is zero since the voltage produced by the incoming current to the load gets nulli¬fied by the outgoing current through the neutral. Thus the electrical energy measured will be the actual energy consumed. In condition 2 shown in fig. 2, the phase and neutral arc inter¬changed. The meter according to the invention will still read the energy consumed by the load correctly, under this condition. In condition,3, shown in fig.2, the supply terminals and load

terminals are interchanged and in condition 4, in fig. 2 in addition to interchanging the supply terminals and load termi¬nals, the phase and neutral are reversed. The meter according to the invention will read the energy consumed correctly. It will also be indicated by the LED display showing direction reversal.
In condition 5 shown in fig. 5 one end of the load is earthed and the load is not returned to the neutral. In this condition the meter according to the invention will indicate twice the energy of actual consumption since the current trans¬former output is not nullified by the return current through the neutral. Thus the input to the measuring means (10) wil1 correspond to two times the current flowing through the load. This will result in penalizing the consumer 100% additional charge for the energy tampered and charging normal for the untam-pered energy. The LED display (15) will indicate earth tamper¬ing. In condition 8 shown in fig. 3 the neutral and phase con¬nections are interchanged and the load is returned to earth instead of neutral. The meter according to the invention will read the actual energy consumed under this condition. There will not be any voltage drop on the shunt resistance (6), But the output of the current transformer (7) will be in accordance with the energy consumed and this will be recorded by the meter. In condition 7 shown in fig. 3 the load is connected to supply terminals (IS and 2S) and the supply is connected to the load terminals (IL and 2L). The meter according to the invention will

indicate twice the energy actually consumed. The voltage across the shunt resistor (6) will be added with the output of the current transformer (7) which will also be proportional to the energy consumed since the current transformer output will not be nullified when the load is not returned to the neutral. This will again result in penalizing the consumer with 100% more charges far the tampered energy and normal for unhampered energy. The LED display (14) and the LED display Thus the electronic single phase energy meter according to the invention will never show a reading less than the actual energy consumed in all possible type of tampering. It will penalize the tampering consumer by indicating double the tampered energy consumed under condition 9 and condition 7 shown in fig. 3. Such an energy meter can effectively deter tampering of the meter at the consumer end.

WE CLAIM:
1. An electronic single phase energy meter comprising a terminal block (1) with terminals for connecting phase (2), neutral (3) and load (5), a shorting link (4) for isolation of phase during testing characterized in that a shunt resistor (6) is connected between the phase terminal (2) and one of the load terminals for sensing the load current, a current transformer (7) in which both the line from phase terminal (2) and the line returning to neutral terminal (3) are passed through the central portion as primary, for providing a current transformer output proportional to the difference between the phase current and the return neutral current, the voltages across the shunt resistor and the current transformer output being connected to the input of a summation circuit (9), the output from the summation circuit (9) and voltage between phase and neutral are connected to an energy measuring means (10) providing output signals for recording energy consumed and meter tampering.
2. The electronic single phase energy meter, as claimed in claim 1, wherein the voltage between phase and neutral is connected to the energy measuring means (10) through a voltage attenuator (B).
3. The electronic single phase energy meter, as claimed in claims 1 or 2, wherein the output signal from the energy measuring means (10) indicating the energy consumed is connected to a frequency counter (11) connected to impulse counter (12) for indicating energy consumed and an LED display (13) for indicating meter constant.
4. The electronic single phase energy meter, as claimed in any one of the previous clauns, wherein the output signals from the energy measuring means (10) indicating direction reversal

and meter tampering are connected to direction reversal indicating display (14) and earth tamper indicating display (15) respectively.
5. The electronic single phase energy meter, as claimed in claim 3, wherein the frequency counter (11) is a digital counter.
6. The electronic single phase energy meter, as claimed in any one of the previous claims, wherein the terminal block (1) is provided with a shorting link (4) to isolate phase line from shunt resistor (6) during testing.
7. An electronic single phase energy meter, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Documents:

1516-mas-1997 form-13 24-07-2009.pdf

1516-mas-1997 form-26 24-07-2009.pdf

1516-mas-97 abstract.pdf

1516-mas-97 assignment.pdf

1516-mas-97 claims.pdf

1516-mas-97 correspondence-others.pdf

1516-mas-97 correspondence-po.pdf

1516-mas-97 description(complete)-duplicate.pdf

1516-mas-97 description(complete).pdf

1516-mas-97 drawings.pdf

1516-mas-97 form-1.pdf

1516-mas-97 form-10.pdf

1516-mas-97 form-19.pdf

1516-mas-97 form-26.pdf

« Previous Patent

Next Patent »

Patent Number

217245

Indian Patent Application Number

1516/MAS/1997

PG Journal Number

21/2008

Publication Date

23-May-2008

Grant Date

26-Mar-2008

Date of Filing

07-Jul-1997

Name of Patentee

LARSEN & TOUBRO LIMITED

Applicant Address

L & T HOUSE, BALLARD ESTATE, MUMBAI 400 001,

Inventors:

#	Inventor's Name	Inventor's Address
1	JOHN PARAPPALLICHIRAYIL ZACHARIA	KIAB, INDUSTRIAL AREA, HEBBAL, HOOTAGALLI, MYSORE 571 186,
2	BIJU THOTTAKKATT ABRAHAM	KIAB, INDUSTRIAL AREA, HEBBAL, HOOTAGALLI, MYSORE 571 186,

PCT International Classification Number

G01R 21/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA