Title of Invention	"AN ELECTRONIC INSTRUMENT FOR PROCESS CONTROL IN STEEL PLANTS"
Abstract	The invented instrument is capable of detecting the presence of light-emitting heated objects, light reflecting non-heated objects and any other object through the method of light interruption in different locations of steel plants and comprises of two separate units, (a) a 'sensor' and (b) a 'monitor', inter-connected electrically by means of a 2-3 core cable, of which the sensor, comprising of a phototransistor and other electronic components, is positioned near the object to be detected and monitor is positioned at a distance upto 150m from the sensor at a central place in the steel plants, wherein the sensor is provided with an electronic circuit (figure 1) and the monitor comprises of an electronic circuit (figure 2) having optionally an opto-coupler unit (OC) for electrically isolating the sensor from the monitor. The instrument is of relatively low-cost construction, easily repairable, adequately sensitive and suitable for increasing the productivity, and reducing wastages of materials ,in steel plants.

Title of Invention

"AN ELECTRONIC INSTRUMENT FOR PROCESS CONTROL IN STEEL PLANTS"

Abstract

The invented instrument is capable of detecting the presence of light-emitting heated objects, light reflecting non-heated objects and any other object through the method of light interruption in different locations of steel plants and comprises of two separate units, (a) a 'sensor' and (b) a 'monitor', inter-connected electrically by means of a 2-3 core cable, of which the sensor, comprising of a phototransistor and other electronic components, is positioned near the object to be detected and monitor is positioned at a distance upto 150m from the sensor at a central place in the steel plants, wherein the sensor is provided with an electronic circuit (figure 1) and the monitor comprises of an electronic circuit (figure 2) having optionally an opto-coupler unit (OC) for electrically isolating the sensor from the monitor. The instrument is of relatively low-cost construction, easily repairable, adequately sensitive and suitable for increasing the productivity, and reducing wastages of materials ,in steel plants.

Full Text	The present invention relates to an.electronic instrument for process control in steel plants. The invention relates more particularly to an instrument which is suitable for detecting the presence of light-emitting heated objects and also light-reflecting non-heated objects and also any object through method of light interruption in different locations in steel plants such as rail end structural mills, plate mills, blooming mills, billet mills, skelp mills, wire rod mills, merchant mills, continuous casting mills in steel plants; also for detecting the presence of furnace flame and controlling the limit switches of cranes/ other machines used in steel plants. The devices used at present for detecting the presence of light emitting/reflecting objects in steel plants have the drawbacks in that these are (i) very expensive, (ii) not readily repairable, (iii) not adequately sensitive, (iv) liable to be out of order through inadvertent operational errors (v) slow to respond, (vi) needs 7/8-core cable between the sensor and monitor unit, (vii) contain amplifier circuit at sensor end, and (viii) require a large space at site for installation, The object of the invention is to provide an instrumen1 which is relatively inexpensive, easily repairable, sensitive, not liable to be damaged through inadvertent operational errors, fast-responsive, and is particularly suitable for use in steel plants for increasing the productivity and reducing the wastage of materials through control of the processes. The invented instrument is called "SAIL-PHOS". It is built in two separate units, namely 'sensor1 and 'monitor1, which are inter-connected electrically through a 2 or 3-wire cable. The sensor unit is built in a metallic casing of typical dimensions 6mm {dia) x 20 mm (L) or 25x25x15mm or 100x50x25mm, and is provided with a focussing hood of preferred length 50 or 100 or 150mm optional to allow only the desired light/heat rays from an object to enter into it through a focussing lense of preferred diameter 5 to 10mm and fall on a photo transistor provided in the unit , the electrical output of which is amplified by means of an electronic circuit connected to the photo transistor, comprising only a relatively few components and kept inthe monitor unit. The casing of the sensor unit is mounted on a stand which is rotatable both in the horizontal and vertical planes for directing the hood towards the object to be detected. The sensor unit is suitable for operation at an ambient temperature upto 90°C without using any cooling jacket. A cooling jacket is provided for using the sensing unit at an ambient temperature above 90°C. The amplified electrical output of the photo transistor is compared against a threshold signal supplied to the sensor unit from the monitor unit, and the photo transistor output, which is in excess of the threshold signal level, is produced at the output of the sensor unit and fed at input of the monitor unit. At least one 3V bulb is provided in the sensor unit, for testing operating condition of instrument when no light rays are received from an object to be detected. With a view to ensuring the safety of the operating personnel during adjustment of the focussing direction of the hood of the sensor unit at site, only a low d.c. voltage supply of around 12V is provided in the sensor unit. The monitor unit which is meant for installation at a central place such as the electrical control room/electrical machine hall/computer room pulpits, which may be at an appreciable distance away from the location of the object to be detected by the sensor unit, the electrical connection between the two units i.e. sensor and monitor, is made by means of an adequately long 2/3-wire cable, which may be screened or not screened. The power supply to the monitor unit is 220V, A«C-mains. The output of the sensor unit supplied to the input of the monitor unit is received optionally through an opto-coupler provided in the monitor unit for electrically isolating the sensor unit from the monitor unit. The output of the opto-coupler when used or that of sensor unit when the opto-coupler is not used is fed to a relay and an open-collector transistor, after being amplified through a high current-gain amplifier. The monitor unit contains a potentiometer for controlling the level of the threshold signal supplied to the sensor unit. A test signal is available from the monitor unit for testing the operating conditions of the sensor unit, as well as the cable connecting the sensor unit with the monitor unit and the monitor unit itself, when no object is present in the viewing zone of the sensor unit. The invention is described fully and particularly in an unrestricted manner with reference to the accompanying drawings, in which Figure 1 is the electrical circuit diagram of the sensor unit; and Figure 2 is the electrical circuit diagram of the monitor unit. Referring to Fig. 1, the sensor unit contains a photo transistor P, the output voltage of which is fed at the input terminals 12, 13 of IC1. The output of IC1 obtained at terminal 14 is fed to the input terminal 10 of IC2 through resistor R5. A part of the output of IC1 is fed back from terminal 14 to terminal 13 through resistor R4. A part of the output of IC2 obtained at its terminal 8 is fed back to its input terminal 9 through the gain control potentiometer P1 and resistors R9 and R6. The output of IC2 at its terminal 8 is available at terminal TP1 and is supplied also to the input terminal 5 of IC3, through resistor R7, which acts as a comparator to block the signal at terminal 5, which is of lower strength than the threshold signal fed at terminal 6 of IC3. A Part of the output of IC3 obtained at terminal 7 is fed back to its input terminal 5 through resistor R8. The output of IC3 at terminal 7 is supplied to base (b) of transistor T2 through resistor R14. Transistor T2 is connected e-in grounded-amitter and open-collector mode. The output of T2, obtained at terminal SL1, is connected to the opto-coupler unit (OC) of type MCT2 shown in Fig. 2, Threshold voltage obtained at terminal TH of sensor unit from the monitor unit (Fig. 2) is fed at terminal 3 of IC4 through resistor R3 The output signal at terminal 1 of IC4 is connected to terminal 6 of IC3 which acts as a threshold comparator for comparing the threshold signal against the photo-transistor atignal(Fig. 1). Referring to Fig. 2, the signal received from terminal SL1 of the sensor unit (Fig. 1) is connected to terminal 3 of the opto-coupler unit OC (type MCT2), provided in the monitor unit. The opto-coupler is used to electrically isolate the sensor unit from the monitor unit. The capacitor C3 connected between terminal 7 and ground of the opto-coupler unit is meant for by-passing the transient surge voltages.in the signal received from terminal SL1 of the sensor unit. Voltage VCC is supplied to terminal 8 of the opto-coupler directly and to terminals 2 and 6 of the opto-coupler through resistors R26 and R27 respectively. The terminal 5 of opto-coupler is connected to ground. The output signal at terminal 6 of opto-coupler is fed at terminal 13 of 1C5. The output obtained at terminal 1A of IC5 is connected to base (b) of transistor T6 in two ways, namely, directly through junction J1, resistor R28,and through IC6, junction J2 and resistor R28. The output obtained at emitter (e) of T5 is supplied to base (b) of transistors T3 and T7 each through resistors R2A and R25 respectively. Transistor T3 is connected in grounded-emitter {e) and open-collector (c) mode, and provides output at terminal OC through switch S1. The output obtained at collector (c) of T7» which is connected in grounded-emitter (e) mode, is supplied to relay RL. Diode D6 is connected across the relay to discharge the back e.m.f. generated in the relay during switching off of the switch S2. Resistor R23 and diode D5 act as collector load of T7. A dc voltage which is adjustable by potentiometer P2 is supplied from VCC to the input terminal 5 of IC7 (optional), the output of which obtained at terminal 7 thereof is fed at base (b) of transistor TA (optional) which is connected in open collector {c) configuration. The voltage obtained at the collector (c) of TA is available at terminal TH as the threshold voltage which is provided at terminal TH of the sensor unit (Fig. 1). In this way, the photo transistor output produced by stray light rays is cancelled by IC3 (Fig. 1) in its output at terminal 7. The power supply section (Fig. 2) comprises transformer Tr, diodes D1, D2, D3, D4, Capacitors C1, C2, L.E.D* V7, register R19, voltage regulator VRand generates a dc voltage (12V) at terminal VCC, from the A-C- mains voltage 220V supplied at terminals L and N. VCC is connected to terminal 5 of IC7 through diode D8 and to terminal 10 of IC8 from the Junction of resistors R17 and R18 when the test press button PB is pressed. An auxiliary light source 3V bulb is provided in the sensor unit (Fig. 1) for testing the operating condition of the sensor unit (Fig. 1), monitor unit (Fig. 2) and the Cable used for connecting the sensor unit with the monitor unit, when an object to be detected by the instrument is not present at a given location in the plant. The instrument is provided with a base plate having four holes one each at the four corners thereof for fixing the same with similar plates mounted at different locations in the plant, where the instrument is to be fixed by means of nuts and bolts. In operating the instrument, the power supply in the monitor unit is switched on, the press button PB is pressed, the potentiometer P1 (Fig. 1) and P2 (Fig. 2) are adjusted to ensure that the L.E.D. glows in the test mode of the instrument. Suitable focussing distances of the instruments from different objects to be detected and the temperature of the said objects are presented in Table I. (Table Removed) The instrument has been put under trial tests in a number of steel plants with the results so far obtained being found satisfactory. We claim: 1: An electronic instrument for process control in steel plants, which is capable of detecting the presence of light-emitting heated objects, light reflecting non-heated objects and also any other object through the method of light interruption in different locations of steel plants, and comprises two separate units, namely, a 'sensor' and a 'monitor', inter-connected electrically by means of a cable, of which the sensor is positioned near the object to be detected at a distance from 10mm to 50m and monitor is positioned at a distance upto 150m from the sensor at a central place in the steel plants, characterized in that (a) the sensor is built without/with a metallic casing having a focussing hood to focus the desired light rays emitted by or reflected from the object or interrupted by the objects to be detected, onto a phototransistor (P) , and connected to an electronic circuit ,such as herein described, located outside the sensor , to amplify the signal obtained1' from the phototransistor to the desired level, to compare the amplified signal with a threshold signal (TH) for blocking the phototransistor signal produced by stray light rays , and to glow at least one 3V bulb for testing the operating condition of the instrument in the absence of any object in the field of view of the sensor; (b) the monitor comprises an electronic circuit ,such as herein described, having optionally an opto-coupler unit (OC) for electrically isolating the sensor from the monitor and by-passing to ground the transient surge voltages in the signal received from the output of the sensor, an amplifier to amplify the opto-coupler output for actuating a relay (RL), an arrangement for supplying an adjustable threshold signal (TH) to the sensor, an arrangement for supplying the required test signal (TS) to the sensor, a power supply unit for producing a regulated dc voltage (VCC) of 12 V from the A. C. 220V mains supply as required for operation of both the sensor and monitor, and (c) the cable used for connecting the sensor and the monitor is of 2/3-wire, screened or unscreened type. 2: The instrument as claimed in claim 1 wherein the monitor unit comprises of the following components. integrated circuits 1C 5 -1C 8, resistors R 15 - R 20, R 22 -R 29, diodes Dl - D6 and D8, LED (D 7) , transistors T3 -T7, opto-coupler (MCT 2), capacitors Cl - C3, relay (RL), voltage regulator (VR) , transformer (Tr) , potentiometer (P2) and switches. 3: The instrument as claimed in 1, wherein sensor unit is built in different sizes from 25 mm x 25 mm x 15 mm to 100 mm x 50 mm x 50 mm and 6 mm dia x 20 mm (length) . 4. The instrument as claimed in any preceding claims, which is capable of focussing in vertical and horizontal directions through a reliable mounting arrangement provided for the sensor unit. 5. The instrument as claimed in any preceding claim, which is capable of operating at upto 90°C ambient without cooling and at a higher temperature when cooling jacket/heat protecting sheet is fitted thereto.

Full Text

The present invention relates to an.electronic
instrument for process control in steel plants.
The invention relates more particularly to an instrument which is suitable for detecting the presence of light-emitting heated objects and also light-reflecting non-heated objects and also any object through method of light interruption in different locations in steel plants such as rail end structural mills, plate mills, blooming mills, billet mills, skelp mills, wire rod mills, merchant mills, continuous casting mills in steel plants; also for detecting the presence of furnace flame and controlling the limit switches of cranes/ other machines used in steel plants.
The devices used at present for detecting the presence of light emitting/reflecting objects in steel plants have the drawbacks in that these are (i) very expensive, (ii) not readily repairable, (iii) not adequately sensitive, (iv) liable to be out of order through inadvertent operational errors (v) slow to respond, (vi) needs 7/8-core cable between the sensor and monitor unit, (vii) contain amplifier circuit at sensor end, and (viii) require a large space at site for installation,
The object of the invention is to provide an instrumen1 which is relatively inexpensive, easily repairable, sensitive, not liable to be damaged through inadvertent operational errors, fast-responsive, and is particularly suitable for use in steel plants for increasing the productivity and reducing the wastage of materials through control of the processes.

The invented instrument is called "SAIL-PHOS". It is built in two separate units, namely 'sensor1 and 'monitor1, which are inter-connected electrically through a 2 or 3-wire cable.
The sensor unit is built in a metallic casing of typical dimensions 6mm {dia) x 20 mm (L) or 25x25x15mm or 100x50x25mm, and is provided with a focussing hood of preferred length 50 or 100 or 150mm optional to allow only the desired light/heat rays from an object to enter into it through a focussing lense of preferred diameter 5 to 10mm and fall on a photo transistor provided in the unit , the electrical output of which is amplified by means of an electronic circuit connected to the photo transistor, comprising only a relatively few components and kept inthe monitor unit. The casing of the sensor unit is mounted on a stand which is rotatable both in the horizontal and vertical planes for directing the hood towards the object to be detected. The sensor unit is suitable for operation at an ambient temperature upto 90°C without using any cooling jacket. A cooling jacket is provided for using the sensing unit at an ambient temperature above 90°C.
The amplified electrical output of the photo transistor is compared against a threshold signal supplied to the sensor unit from the monitor unit, and the photo transistor output, which is in excess of the threshold signal level, is produced at the output of the sensor unit and fed at input of the monitor unit.

At least one 3V bulb is provided in the sensor unit, for testing operating condition of instrument when no light rays are received from an object to be detected.
With a view to ensuring the safety of the operating personnel during adjustment of the focussing direction of the hood of the sensor unit at site, only a low d.c. voltage supply of around 12V is provided in the sensor unit.
The monitor unit which is meant for installation at a central place such as the electrical control room/electrical machine hall/computer room pulpits, which may be at an appreciable distance away from the location of the object to be detected by the sensor unit, the electrical connection between the two units i.e. sensor and monitor, is made by means of an adequately long 2/3-wire cable, which may be screened or not screened.
The power supply to the monitor unit is 220V, A«C-mains. The output of the sensor unit supplied to the input of the monitor unit is received optionally through an opto-coupler provided in the monitor unit for electrically isolating the sensor unit from the monitor unit.
The output of the opto-coupler when used or that of sensor unit when the opto-coupler is not used is fed to a relay and an open-collector transistor, after being amplified through a high current-gain amplifier. The monitor unit contains a potentiometer for controlling the level of the threshold signal supplied to the sensor unit.

A test signal is available from the monitor unit for testing the operating conditions of the sensor unit, as well as the cable connecting the sensor unit with the monitor unit and the monitor unit itself, when no object is present in the viewing zone of the sensor unit.
The invention is described fully and particularly in an unrestricted manner with reference to the accompanying drawings, in which
Figure 1 is the electrical circuit diagram of the sensor unit; and
Figure 2 is the electrical circuit diagram of the monitor unit.
Referring to Fig. 1, the sensor unit contains a photo transistor P, the output voltage of which is fed at the input terminals 12, 13 of IC1. The output of IC1 obtained at terminal 14 is fed to the input terminal 10 of IC2 through resistor R5.
A part of the output of IC1 is fed back from terminal 14 to terminal 13 through resistor R4.
A part of the output of IC2 obtained at its terminal 8 is fed back to its input terminal 9 through the gain control potentiometer P1 and resistors R9 and R6. The output of IC2 at its terminal 8 is available at terminal TP1 and is supplied also to the input terminal 5 of IC3, through resistor R7, which acts as a comparator to block the signal at terminal 5, which is of lower strength than the threshold signal fed at terminal 6 of IC3.

A Part of the output of IC3 obtained at terminal 7 is fed back to its input terminal 5 through resistor R8. The output of IC3 at terminal 7 is supplied to base (b) of
transistor T2 through resistor R14. Transistor T2 is connected
e-in grounded-amitter and open-collector mode. The output of T2,
obtained at terminal SL1, is connected to the opto-coupler unit (OC) of type MCT2 shown in Fig. 2,
Threshold voltage obtained at terminal TH of sensor unit from the monitor unit (Fig. 2) is fed at terminal 3 of IC4 through resistor R3 The output signal at terminal 1 of IC4 is connected to terminal 6 of IC3 which acts as a threshold comparator for comparing the threshold signal against the photo-transistor atignal(Fig. 1).
Referring to Fig. 2, the signal received from terminal SL1 of the sensor unit (Fig. 1) is connected to terminal 3 of the opto-coupler unit OC (type MCT2), provided in the monitor unit. The opto-coupler is used to electrically isolate the sensor unit from the monitor unit. The capacitor C3 connected between terminal 7 and ground of the opto-coupler unit is meant for by-passing the transient surge voltages.in the signal received from terminal SL1 of the sensor unit. Voltage VCC is supplied to terminal 8 of the opto-coupler directly and to terminals 2 and 6 of the opto-coupler through resistors R26 and R27 respectively. The terminal 5 of opto-coupler is connected to ground. The output signal at terminal 6 of opto-coupler is fed at terminal 13 of 1C5. The output obtained at terminal 1A of IC5 is connected to base (b) of transistor T6 in two ways,

namely, directly through junction J1, resistor R28,and through IC6, junction J2 and resistor R28. The output obtained at emitter (e) of T5 is supplied to base (b) of transistors T3 and T7 each through resistors R2A and R25 respectively.
Transistor T3 is connected in grounded-emitter {e) and open-collector (c) mode, and provides output at terminal OC through switch S1. The output obtained at collector (c) of T7» which is connected in grounded-emitter (e) mode, is supplied to relay RL. Diode D6 is connected across the relay to discharge the back e.m.f. generated in the relay during switching off of the switch S2. Resistor R23 and diode D5 act as collector load of T7.
A dc voltage which is adjustable by potentiometer P2 is supplied from VCC to the input terminal 5 of IC7 (optional), the output of which obtained at terminal 7 thereof is fed at base (b) of transistor TA (optional) which is connected in open collector {c) configuration. The voltage obtained at the collector (c) of TA is available at terminal TH as the threshold voltage which is provided at terminal TH of the sensor unit (Fig. 1). In this way, the photo transistor output produced by stray light rays is cancelled by IC3 (Fig. 1) in its output at terminal 7.
The power supply section (Fig. 2) comprises transformer Tr, diodes D1, D2, D3, D4, Capacitors C1, C2, L.E.D* V7, register R19, voltage regulator VRand generates a dc voltage (12V) at terminal VCC, from the A-C- mains voltage 220V supplied at terminals L and N. VCC is connected to terminal 5 of IC7

through diode D8 and to terminal 10 of IC8 from the Junction of resistors R17 and R18 when the test press button PB is pressed.
An auxiliary light source 3V bulb is provided in the sensor unit (Fig. 1) for testing the operating condition of the sensor unit (Fig. 1), monitor unit (Fig. 2) and the Cable used for connecting the sensor unit with the monitor unit, when an object to be detected by the instrument is not present at a given location in the plant.
The instrument is provided with a base plate having four holes one each at the four corners thereof for fixing the same with similar plates mounted at different locations in the plant, where the instrument is to be fixed by means of nuts and bolts.
In operating the instrument, the power supply in the monitor unit is switched on, the press button PB is pressed, the potentiometer P1 (Fig. 1) and P2 (Fig. 2) are adjusted to ensure that the L.E.D. glows in the test mode of the instrument.
Suitable focussing distances of the instruments from different objects to be detected and the temperature of the said objects are presented in Table I.
(Table Removed)
The instrument has been put under trial tests in a number of steel plants with the results so far obtained being found satisfactory.

We claim:
1: An electronic instrument for process control in steel plants, which is capable of detecting the presence of light-emitting heated objects, light reflecting non-heated objects and also any other object through the method of light interruption in different locations of steel plants, and comprises two separate units, namely, a 'sensor' and a 'monitor', inter-connected electrically by means of a cable, of which the sensor is positioned near the object to be detected at a distance from 10mm to 50m and monitor is positioned at a distance upto 150m from the sensor at a central place in the steel plants, characterized in that (a) the sensor is built without/with a metallic casing having a focussing hood to focus the desired light rays emitted by or reflected from the object or interrupted by the objects to be detected, onto a phototransistor (P) , and connected to an electronic circuit ,such as herein described, located outside the sensor , to amplify the signal obtained1' from the phototransistor to the desired level, to compare the amplified signal with a threshold signal (TH) for blocking the phototransistor signal produced by stray light rays , and to glow at least one 3V bulb for testing the operating condition of the instrument in the absence of any object in the field of view of the sensor; (b) the monitor comprises an electronic circuit ,such as herein described, having optionally an opto-coupler unit (OC) for electrically isolating the sensor from the monitor and by-passing to ground the transient surge voltages in the signal received from the output of the sensor, an amplifier to amplify the

opto-coupler output for actuating a relay (RL), an arrangement for supplying an adjustable threshold signal (TH) to the sensor, an arrangement for supplying the required test signal (TS) to the sensor, a power supply unit for producing a regulated dc voltage (VCC) of 12 V from the A. C. 220V mains supply as required for operation of both the sensor and monitor, and (c) the cable used for connecting the sensor and the monitor is of 2/3-wire, screened or unscreened type. 2: The instrument as claimed in claim 1 wherein the monitor unit comprises of the following components. integrated
circuits 1C 5 -1C 8, resistors R 15 - R 20, R 22 -R 29, diodes Dl - D6 and D8, LED (D 7) , transistors T3 -T7, opto-coupler (MCT 2), capacitors Cl - C3, relay (RL), voltage regulator (VR) , transformer (Tr) , potentiometer (P2) and switches.
3: The instrument as claimed in 1, wherein sensor unit is built in different sizes from 25 mm x 25 mm x 15 mm to 100 mm x 50 mm x 50 mm and 6 mm dia x 20 mm (length) .
4. The instrument as claimed in any preceding claims, which
is capable of focussing in vertical and horizontal directions
through a reliable mounting arrangement provided for the
sensor unit.
5. The instrument as claimed in any preceding claim, which
is capable of operating at upto 90°C ambient without cooling
and at a higher temperature when cooling jacket/heat
protecting sheet is fitted thereto.

Documents:

1550-del-1997-abstract.pdf

1550-del-1997-claims.pdf

1550-del-1997-correspondence-others.pdf

1550-del-1997-correspondence-po.pdf

1550-del-1997-description (complete).pdf

1550-del-1997-drawings.pdf

1550-del-1997-form-1.pdf

1550-del-1997-form-19.pdf

1550-del-1997-form-2.pdf

1550-del-1997-gpa.pdf

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Patent Number

220119

Indian Patent Application Number

1550/DEL/1997

PG Journal Number

28/2008

Publication Date

11-Jul-2008

Grant Date

15-May-2008

Date of Filing

11-Jun-1997

Name of Patentee

STEEL AUTHORITY OF INDIA. LTD.,

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. MALAYA RANJAN KHARE,

PCT International Classification Number

G12B 5/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA