FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A common controller for multiple gas circuit breaker system
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Namjoshi Yogendra, Kambli Upendra, Patange Raju and Vaidya Tushar; all of Crompton Greaves Ltd, CG Global R&D Center, Crompton Greaves Limited, Kanjur Marg, Mumbai 400 042, Maharashtra, India; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION:
.This invention relates to the field of electrical and electronic equipment.
Particularly, this invention relates to the field of switchgear equipment and controllers, thereof.
More particularly, this invention relates to the field of circuit breakers, its controllers, and associated devices, thereof.
Specifically, this invention relates to a common controller for multiple gas circuit breaker system.
BACKGROUND OF THE INVENTION:
The term switchgear, used in association with the electric power system, or sub-station or power grid, or power distribution systems, refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. Switchgear are also typically employed to protect the associated system against abnormal conditions, such as power line fault conditions or irregular loading conditions or transients. This type of equipment is important because it is directly linked to the reliability of the electricity supply and the electrical load.
Different types of switchgear exist for different applications. A fault interrupter is one type of switchgear. Fault interrupters are employed to automatically open a power line upon the detection of a fault condition.
Circuit breakers are one type of switchgear component. A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to interrupt continuity upon detection of a fault condition to immediately discontinue electrical flow. The circuit breaker must react to fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip coil that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.

Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts. Small circuit breakers may be manually operated; larger units have coils to trip the mechanism, and electric motors to restore energy to the springs.
To switch on/off current in electrical systems, a set of contacts may be used. The contacts may be either in an open position, resulting in the stopping of current flow, or in a closed position that allows current flow. The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting (opening) the circuit. Contacts are made of copper or copper alloys, silver alloys, and other highly conductive materials.
A trip coil is a type of solenoid in which the moving armature opens a circuit breaker or other protective device when the coil current exceeds a predetermined value. A closing coil is adapted to shut the circuit breaker completely.
In its working mode, if a power surge occurs in the electrical system, the breaker will trip. This means that a breaker that was in the "on" position will flip to the "off position and shut down the electrical power leading from that breaker. Essentially, a circuit breaker is a safety device. When a circuit breaker is tripped, it may prevent a fire from starting on an overloaded circuit; it can also prevent the destruction of the device that is drawing the electricity.
For circuit breaker operation controllers, are used for their actuation. These controllers may include point-on -wave switching mechanisms. The aim of point-on-wave switching is to minimize switching transients, over-voltages and current surges, thereby reducing the stress on equipment insulation. To achieve this, it requires a control device that receives a random command for circuit breaker operation, and synchronizes it with a reference signal, such that the circuit breaker operates at a specified point-on-wave (POW). This is achieved with the help of an electronic device i.e. controller along with circuit breaker.
The point-on-wave switching is also called as controlled switching or synchronous switching.
According to the prior art, different controllers have to be provided for different breaker systems;

especially for systems with multiple-poles per each phase. This adds the task of maintaining versions across production, manufacturing, and servicing the equipment.
Typically, the SF6 gas circuit breaker is available in three types for three different voltage ratings: Type 1: Single-make Single-pole per phase for voltages lesser than 420kV Type 2: Double-make Single-pole per phase for 420kV and Type 3: Four-make Double-pole per phase for 765kV
To enable controlled switching for these circuit breakers there might be a need to design three different controllers for generating outputs for single pole (close and trip commands) or double poles (commands twice that of single pole) and/or wiring schemes with the controller. Same is the case of inputs or feedbacks. Providing different controllers for the different types results in overheads on production, manufacturing, and servicing / retrofitting of controller for different circuit breakers in a same bay / substation or different substations.
OBJECTS OF THE INVENTION:
An object of the invention is to provide a common controller for a plurality of versions of makes of gas circuit breaker systems.
Another object of the invention is to provide a common controller with intrapole discrepancy protection for a plurality of versions of makes of gas circuit breaker systems.
Yet another object of the invention is to provide a common controller with interpole discrepancy protection for a plurality of versions of makes of gas circuit breaker systems.
Still another object of the invention is to provide a common controller with external trip provision for a plurality of versions of makes of gas circuit breaker systems.
Still another object of the invention is to provide a common controller with provision for better prospects for circuit breakers lesser or equal to 400kV voltage rating

SUMMARY OF THE INVENTION:
According to this invention, there is provided a common controller for multiple gas circuit breakers,
said controller comprises:
i. multi-phase close feedback means from close coils of said circuit breaker, two lines of each
phase from a three phases supply are provided as input for said multi-phase close feedback
means; ii. multi-phase trip feedback means from trip coils' switching assembly, two lines of each phase
from a three phases supply are provided as input for said multi-phase trip feedback means; iii. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said circuit
breaker through said controller; iv. external pole discrepancy protection means adapted to receive inputs from at least one of each
of said lines across a three phase supply which is given to said multi-phase close feedback
means and to said multi-phase trip feedback means; v. external tripping means adapted to provide external signals in order to provide trip signals
through said controller; and vi. switching assembly adapted to provide switching signals for actuation for each of said main
trip coils, said auxiliary trip coils, and said close coils based on received signals.
According to this invention, there is also provided a common controller for single make single pole gas circuit breaker, said controller comprises:
a. multi-phase close feedback means from close coils of said circuit breaker, one line of each
phase from a three phases supply are provided as input for said multi-phase close feedback
means;
b. multi-phase trip feedback means from trip coils' switching assembly, one line of each phase
from a three phases supply are provided as input for said multi-phase trip feedback means;
c. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said circuit
breaker through said controller;
d. external pole discrepancy protection means adapted to receive inputs from at least one of each
of said lines across a three phase supply which is given to said multi-phase close feedback
means and to said multi-phase trip feedback means;
e. external tripping means adapted to provide external signals in order to provide trip signals
through said controller; and

f. switching assembly adapted to provide switching signals for actuation for each of said main trip coils, said auxiliary trip coils, and said close coils based on received signals.
According to this invention, there is also provided a common controller for two make single pole gas circuit breaker, said controller comprises:
A. multi-phase close feedback means from close coils of said circuit breaker, one line of each
phase from a three phases supply are provided as input for said multi-phase close feedback
means;
B. multi-phase trip feedback means from trip coils' switching assembly, one line of each phase
from a three phases supply are provided as input for said multi-phase trip feedback means;
C. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said circuit
breaker through said controller;
D. external pole discrepancy protection means adapted to receive inputs from at least one of each
of said lines across a three phase supply which is given to said multi-phase close feedback
means and to said multi-phase trip feedback means;
E. external tripping means adapted to provide external signals in order to provide trip signals
through said controller; and
F. switching assembly adapted to provide switching signals for actuation for each of said main trip
coils, said auxiliary trip coils, and said close coils based on received signals.
According to this invention, there is also provided a common controller for four make double pole gas circuit breaker, said controller comprises: I. multi-phase close feedback means from close coils of said circuit breaker, one line of each
phase from a three phases supply are provided as input for said multi-phase close feedback
means; II. multi-phase trip feedback means from trip coils' switching assembly, one line of each phase
from a three phases supply are provided as input for said multi-phase trip feedback means;
III. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said circuit breaker through said controller;
IV. inter-pole discrepancy monitoring adapted to monitor inter-pole discrepancy in said circuit breaker through said controller;
V. external pole discrepancy protection means adapted to receive inputs from at least one of each of said lines across a three phase supply which is given to said multi-phase close

feedback means and to said multi-phase trip feedback means; VI. external tripping means adapted to provide external signals in order to provide trip signals
through said controller; and VII. switching assembly adapted to provide switching signals for actuation for each of said main
trip coils, said auxiliary trip coils, and said close coils based on received signals.
Typically, said common controller comprising intra-pole timers, logic wiring, and external trip command in order to provide external tripping.
Typically, said common controller comprising input means adapted to input 3-phase grid voltage and 3-phase grid current.
Typically, said common controller comprising input means adapted to input analog inputs, digital inputs, station supply inputs, command inputs by a user and feedback inputs so that a computational mechanism of said controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil, close coil, or auxiliary tripping coil along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
Typically, said common controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored.
Typically, said common controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored, said controller means adapted to monitor power frequency current and voltage waveform.
Typically, said common controller comprising a point-on-wave sensing mechanism adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions.
Typically, said common controller comprising input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter

(delay) for main trip coil; mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
According to a first embodiment, said switching assembly comprises a first switching system for a single phase of a single make / two make single pole gas circuit breaker, said first switching system comprises:
• first switching means for a main trip coil of said circuit breaker, said first switching means
adapted to receive first trip command from said controller;
• second switching means for an auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
• third switching means for a first close coil of said circuit breaker, said third switching means adapted to receive close command from said controller.
According to a second alternative embodiment, said switching assembly comprises a first switching system for a single phase of a single make / two make single pole gas circuit breaker, said first switching system comprises:
first switching means in a parallel configuration with a second switching means for a main trip coil of said circuit breaker, said first switching means and said second switching means adapted to receive first trip command from said controller;
third switching means in a parallel configuration with a fourth switching means switching means for an auxiliary trip coil of said circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and fifth switching means in a parallel configuration with a sixth switching means for a close coil of said circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller.
According to a third embodiment, said switching assembly comprises a second switching system for a single phase of four make double pole gas circuit breaker, said system comprises:
first switching means for a first main trip coil as well as a second main trip coil, said first

switching means adapted to receive first trip coil command from said controller; second switching means for a first auxiliary trip coil and a second auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
third switching means for a first close coil and a second close coil of a circuit breaker, said third switching means adapted to receive close command from said controller; each of said first, second, and third switching means being provided with a NO/NC relay in series.
According to a fourth alternative embodiment, said switching assembly comprises a second
switching system for a single phase of four make double pole gas circuit breaker, said system
comprises:
o first switching means in a parallel configuration with a second switching means for a first main trip coil as well as a second main trip coil, said first switching means and said second switching means adapted to receive first trip coil command from said controller;
o a third switching means in a parallel configuration with a fourth switching means for a first auxiliary trip coil and a second auxiliary trip coil of a circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and
o fifth switching means in a parallel configuration with a sixth switching means for a first close coil and a second close coil of a circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller,
each of the switching means being provided with a NO/NC relay in series.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a controller means of the prior art.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 2 illustrates a controller means of the current invention which is typically suited for a Four-make Double-pole gas circuit breaker;
Figure 3 illustrates a controller means of the current invention which is typically suited for a single make / two make single pole gas circuit breaker;

Figure 4a illustrates a first switching system;
Figure 5a illustrates a third switching system;
Figure 4b illustrates a second switching system;
Figure 5d illustrates a fourth switching system;
Figure 7 illustrates a flowchart (and method) of the additional logic of controller action of the invention; and
Figure 6 illustrates a flowchart (and method) of controller action of the prior art.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a controller means (CM) of the prior art used to control a main tripping coil (MTC), a close coil (CC), and an auxiliary tripping coil (ATC) in a circuit breaker assembly (CB). The main tripping coil functions as a normal tripping coil. Its actuation is governed by a controller and it serves to trip the breaker in cases of tripping command as sensed by the controller. The auxiliary tripping coil functions as a backup tripping coil whose actuation is also governed by a controller.
Inputs in the form of 3-phase grid voltage (GV) and 3-phase grid current (GC) are supplied. Further, analog inputs (AI), digital inputs (DI), station supply inputs (SSI), command inputs (CI) by a user and feedback inputs (FI) are provided to the controller so that the computational mechanism of the controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of tripping coil (MTC), close coil (CC), or auxiliary tripping coil (ATC) along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
According to this invention, there is provided a controller for circuit breaker, said circuit breaker being either a single make / two make single pole gas circuit breaker or a four make double pole gas circuit breaker.

Figure 2 illustrates a controller means (CMM-1) of the current invention which is typically suited for a Four-make Double-pole gas circuit breaker. Figure 3 illustrates a controller means (CMM-2) of the current invention which is typically suited for a single make / two make single pole gas circuit breaker.
In accordance with an embodiment of this invention, there is provided a multi-phase close feedback means from close coils (CFB). Two lines of each phase from the three phases supply are provided as input of multi-phase close feedback means at the controller. In case of single make / two make single pole gas circuit breaker; one line of each phase is ground (as shown in Figure 3 of the accompanying drawings).
In accordance with another embodiment of this invention, there is provided a multi-phase trip feedback means from trip coils (TFB). Two lines of each phase from the three phases supply are provided as input of multi-phase trip feedback means at the controller. In case of single make / two make single pole gas circuit breaker; one line of each phase is ground (as shown in Figure 3 of the accompanying drawings).
Inputs in the form of 3-phase grid voltage (GV) and 3-phase grid current (GC) are supplied. Further, analog inputs (AI), digital inputs (DI), station supply inputs (SSI), command inputs (CI) by a user and feedback inputs (FI) are provided to the controller so that the computational mechanism of the controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil (MTC), close coil (CC), or auxiliary tripping coil (ATC) along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
In accordance with yet another embodiment of this invention, there is provided a external pole discrepancy protection means (EXTPOL). The external pole discrepancy protection means receives inputs from at least one of each of the lines across a three phase supply which is given to the multiphase close feedback means and to the multi-phase trip feedback means.
In accordance with still another embodiment of this invention, there is provided an external tripping means (ETRIP) adapted to provide external signals in order to provide trip signals through the
controller.

The controller is further adapted to include a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored. The controller means monitors power frequency current and voltage waveform. When manual tripping command is given to the controller, it calculates the point on wave (opening time) according to pre-defined compensation parameters. Time delay means is incorporated so that certain pre-defined delay is added if required and contact separation is done at a pre-determined point on power frequency current wave. Since the trip coil timing of both main and auxiliary is same, the configuration of controller is same for both the coils.
In accordance with yet another embodiment of this invention, there is provided a point-on-wave switching module (PSM) adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions. This provides a correct and intelligent switching of circuit breaker in relation to loads in a given house.
Typically, said controller includes input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for main trip coil; mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
According to this invention, there is provided a first switching system (SSM1) for a single phase of a single make / two make single pole gas circuit breaker. Typically, this is used for a 215kV or a 450kV circuit breaker.
Figure 4a illustrates a first switching system (SSM1).
In accordance with an embodiment of this invention, there is provided a first switching means (SMI) for a main trip coil (MTC-1) of a circuit breaker, said first switching means adapted to receive first trip command (TC-1) from a controller (CMM-2 of Figure 3).

In accordance with another embodiment of this invention, there is provided a second switching means (SM2) for an auxiliary trip coil (ATC-1) of a circuit breaker, said second switching means adapted to receive second trip (TC-2) command from a controller (CMM-2 of Figure 3).
In accordance with another embodiment of this invention, there is provided a third switching means (SM3) for a first close coil (CC-1) of a circuit breaker, said third switching means adapted to receive close command (CCM) from a controller (CMM-2 of Figure 3).
The first switching means (SMI), the second switching means (SM2), and the third switching means (SM3) are parallel means.
Figure 5a illustrates a third switching system (SSM3).
Alternatively, in accordance with an embodiment of this invention, there is provided a first switching means (SMI) in a parallel configuration with a second switching means (SM2) for a main trip coil (MTC-1) of a circuit breaker, said first switching means and said second switching means adapted to receive first trip command (TC-1) from a controller (CMM-2 of Figure 3).
Alternatively, in accordance with another embodiment of this invention, there is provided a third switching means (SM3) in a parallel configuration with a fourth switching means switching means (SM4) for an auxiliary trip coil (ATC-1) of a circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from a controller (CMM-2 of Figure 3).
Alternatively, in accordance with another embodiment of this invention, there is provided a fifth switching means (SM5) in a parallel configuration with a sixth switching means (SM6) for a close coil (CC-1) of a circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command (CCM) from a controller (CMM-2 of Figure 3).
According to this invention, there is provided a second switching system (SSM2) for a single phase of four make double pole gas circuit breaker.
Typically, this is used for a 765kV circuit breaker.

Figure 4b illustrates a second switching system (SSM2).
In accordance with an embodiment of this invention, there is provided a first switching means (SMI) for a first main trip coil (MTC-1) as well as a second main trip coil (MTC-2), said first switching means adapted to receive first trip coil command (TC-1) from a controller (CMM-1 of Figure 2).
In accordance with another embodiment of this invention, there is provided a second switching means (SM2) for a first auxiliary trip coil (ATC-1) and a second auxiliary trip coil (ATC-2) of a circuit breaker, said second switching means adapted to receive second trip command (TC-2) from a controller (CMM-1 of Figure 2).
In accordance with another embodiment of this invention, there is provided a third switching means (SM3) for a first close coil (CC-1) and a second close coil (CC-2) of a circuit breaker, said third switching means adapted to receive close command (CCM) from a controller (CMM-1 of Figure 2).
The first switching means, the second switching means, the third switching means, the fourth switching means, the fifth switching means, and the sixth switching means are parallel means.
Each of the switching means may be provided with a NO/NC relay in series.
Figure 5d illustrates a fourth switching system (SSM4).
Alternatively, in accordance with an embodiment of this invention, there is provided first switching means (SMI) in a parallel configuration with a second switching means (SM2) for a first main trip coil (MTC-1) as well as a second main trip coil (MTC-2), said first switching means and said second switching means adapted to receive first trip coil command (TC-1) from a controller (CMM-1 of Figure 2).
Alternatively, in accordance with another embodiment of this invention, there is provided a third switching means (SM3) in a parallel configuration with a fourth switching means (SM4) for a first auxiliary trip coil (ATC-1) and a second auxiliary trip coil (ATC-2) of a circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command (TC-2)

from a controller (CMM-1 of Figure 2).
Alternatively, in accordance with another embodiment of this invention, there is provided a fifth switching means (SM5) in a parallel configuration with a sixth switching means (SM6) for a first close coil (CC-1) and a second close coil (CC-2) of a circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command (CCM) from a controller (CMM-1 of Figure 2).
The first switching means (SMI), the second switching means (SM2), the third switching means (SM3), the fourth switching means (SM4), the fifth switching means (SM5), and the sixth switching means (SM6) are parallel means.
Each of the switching means may be provided with a NO/NC relay in series.
For the controller of Figure 2, there is required an intra-pole discrepancy monitoring as an addition to the inter-pole discrepancy protection / monitoring that is available in the controller of Figure 3. If intrapole discrepancy is managed outside controller through timers and logic wiring, external trip command is added.
Figure 6 illustrates a flowchart (and method) of controller action of the prior art.
Step 1: All inputs are read by the controller.
Step 2: Values are computed by the controller according to pre-defined formulae and techniques.
Step 3: Values of both coil-voltages are stored.
Step 4: Check if there is a command; If Yes, then proceed to Step 5. If No, proceed to Step 17, and
then to Step 18.
Step 5: Check if there are correct feedbacks. If Yes, then proceed to Step 6. If No, then proceed to
Step 16
Step 6: Check for settings (of the controller).
Step 7: If Setting is Main Trip, then compute delay for DC1.
Step 8: If Setting is Redundant Trip, then compute delay for DC2.
Step 9: If Setting is Auto Trip, then check availability of coil-supply and coil-health and proceed to
Step 7 or to Step 8 depending upon if the availability is Main Trip (Step 7) of Redundant Trip (Step
8) or proceed to Step 10.

Step 10: Check if DC1>DC2; If Yes, go to Step 7, If No, go to Step 8.
Step 11: Compute SF6 compensation.
Step 12: Compute air compensation.
Step 13: Compute total compensation.
Step 14: Generate coil commands (trip and close)
Step 15: Check for feedbacks of timeout; If No, go to step 14, If Yes, go to step 17
Step 16: Raise an alarm and go to Step 1.
Step 17: Incorporate additional logic and method as illustrates in Figure 7 of the accompanying
drawings.
Step 18: Check if External Trip; If Yes, then generate discrepancy of fault tripping, If No, go to
Stepl.
Figure 7 illustrates a flowchart (and method) of the additional logic of controller action of the invention.
Step 17a: Check if R-Feedback is same in the two lines (phases i.e. Rl, R2); If Yes, then go to Step
17b, Else go to Step 17e.
Step 17b: Check if Y-Feedback is same in the two lines (phases i.e. Yl, Y2); If Yes, then go to Step
17b, Else go to Step 17f.
Step 17c: Check if B-Feedback is same in the two lines (phases i.e. Bl, B2); If Yes, then go to Step
17b, Else go to Step 17g.
Step 17d: Check if all feedbacks in; If Yes, then go to Step 17q, Else go to Step 17h.
Step 17e: Check if controller has internal or external command; If Internal command, then go to
Step 17m, If External go to Step 17i.
Step 17f: Check if controller has internal or external command; If Internal command, then go to
Step 17n, If External go to Step 17j.
Step 17g: Check if controller has internal or external command; If Internal command, then go to
Stepl7o, If External go to Step 17k.
Step 17h: Check if controller has internal or external command; If Internal command, then go to
Step go to step 17q, If External command go to Step 171.
Step 17i: Check for intrapole discrepancy; If Yes, then go to Step 17m, Else wait for timeout before
checking for intrapole discrepancy again.

Step 17j: Check for intrapole discrepancy; If Yes, then go to Step 17n, Else wait for timeout before
checking for intrapole discrepancy again.
Step 17k: Check for intrapole discrepancy; If Yes, then go to Step 17o, Else wait for timeout before
checking for intrapole discrepancy again.
Step 171: Check for intrapole discrepancy; If Yes, then go to Step 17p, Else wait for timeout before
checking for intrapole discrepancy again.
Step 17m: Trip remaining half pole for R-line.
Step 17n: Trip remaining half pole for Y-line.
Step 17o: Trip remaining half pole for B-line.
Step 17p: Issue trip command to closed poles.
Step 17q; Remove commands from all coils.
Step 17r: Go back to Start of Step 1 (of Figure 6 of the accompanying drawings).
According to this invention, the inventive step lies in provisioning the following, for a circuit breaker:
1. A Controller with point-on-wave switching / synchronous switching / controller switching feature over compensation of variation on parameters such as control-coil-voltage, grid-frequency, temperature, SF6 (sulfur-hexafluoride) gas pressure and air pressure along with adapting to change in mechanical delay of the breaker and idle time of the breaker.
2. A controller with above features along with configurable hardware and software for various control-coil-voltage (70V DC to 260V DC) and different requirements of single-make single-pole per phase gas circuit breakers operating at 245kV, 420kV, and 800kV voltage respectively.
3. A controller with above features along with configurable hardware and software for continuous trip coil supervision for various control-coil-voltage (70V DC to 260 VDC).
4. A controller with common hardware for driving the two-trip and one-close coils per phase for all three types of circuit breakers as discussed above.
5. A controller with SF6 gas pressure compensation for achieving point-on-wave switching for all three types of circuit breakers as discussed above.
6. A controller with programmable pole-discrepancy check for all three types of circuit breakers as discussed above.

The inventive step further comprises the inclusion of the following:
■ One controller can be used for different requirement of single-make single-pole per phase, double-make single-pole per phase and four-make two-pole per phase gas circuit breakers operating at 245kV, 420kV, and 800kV voltage respectively.
■ SF6 gas pressure compensation for all three types of circuit breakers as discussed above.
■ Programmable based hardware re-configuration of trip coil supervision circuit for various voltage ranges (70 - 260 VDC) for all three types of circuit breakers as discussed above.
■ Common hardware circuit for driving trip and close coils of each phase for all three types of circuit breakers as discussed above.
Hence, the following advantages can be observed:
» Common controller for easy production, maintenance, servicing, and retrofitting.
» One controller is suitable for all types of gas circuit breakers.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We Claim,
1. A common controller for multiple gas circuit breakers, said controller comprising:
i. multi-phase close feedback means from close coils of said circuit breaker, two lines of
each phase from a three phases supply are provided as input for said multi-phase close
feedback means; ii. multi-phase trip feedback means from trip coils' switching assembly, two lines of each
phase from a three phases supply are provided as input for said multi-phase trip
feedback means; iii. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said
circuit breaker through said controller; iv. external pole discrepancy protection means adapted to receive inputs from at least one of
each of said lines across a three phase supply which is given to said multi-phase close
feedback means and to said multi-phase trip feedback means; v. external tripping means adapted to provide external signals in order to provide trip
signals through said controller; and vi. switching assembly adapted to provide switching signals for actuation for each of said
main trip coils, said auxiliary trip coils, and said close coils based on received signals.
2. A common controller for multiple gas circuit breakers as claimed in claim 1 wherein, said controller comprising intra-pole timers, logic wiring, and external trip command in order to provide external tripping.
3. A common controller for multiple gas circuit breakers as claimed in claim 1 wherein, said controller comprising input means adapted to input 3-phase grid voltage and 3-phase grid current.
4. A common controller for multiple gas circuit breakers as claimed in claim 1 wherein, said controller comprising input means adapted to input analog inputs, digital inputs, station supply inputs, command inputs by a user and feedback inputs so that a computational mechanism of said controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil, close coil, or auxiliary tripping

coil along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
5. A common controller as claimed in claim 1 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored.
6. A common controller as claimed in claim 1 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored, said controller means adapted to monitor power frequency current and voltage waveform.
7. A common controller as claimed in claim 1 wherein, said controller comprising a point-on-wave sensing mechanism adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions.
8. A common controller as claimed in claim 1 wherein, said controller comprising input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for main trip coil; mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
9. A common controller as claimed in claim 1 wherein, said switching assembly comprising a first switching system for a single phase of a single make / two make single pole gas circuit breaker, said first switching system comprising:
• first switching means for a main trip coil of said circuit breaker, said first switching means adapted to receive first trip command from said controller;

• second switching means for an auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
• third switching means for a first close coil of said circuit breaker, said third switching means adapted to receive close command from said controller.
10. A common controller as claimed in claim 1 wherein, said switching assembly comprising a
first switching system for a single phase of a single make / two make single pole gas circuit
breaker, said first switching system comprising:
first switching means in a parallel configuration with a second switching means for a main trip coil of said circuit breaker, said first switching means and said second switching means adapted to receive first trip command from said controller; - third switching means in a parallel configuration with a fourth switching means switching means for an auxiliary trip coil of said circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and
fifth switching means in a parallel configuration with a sixth switching means for a close coil of said circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller.
11. A common controller as claimed in claim 1 wherein, said switching assembly comprising a
second switching system for a single phase of four make double pole gas circuit breaker,
said system comprising:
first switching means for a first main trip coil as well as a second main trip coil, said first switching means adapted to receive first trip coil command from said controller; second switching means for a first auxiliary trip coil and a second auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
third switching means for a first close coil and a second close coil of a circuit breaker, said third switching means adapted to receive close command from said controller;
each of said first, second, and third switching means being provided with a NO/NC relay in
series.

12. A common controller as claimed in claim 1 wherein, said switching assembly comprising a
second switching system for a single phase of four make double pole gas circuit breaker,
said system comprising:
o first switching means in a parallel configuration with a second switching means for a first main trip coil as well as a second main trip coil, said first switching means and said second switching means adapted to receive first trip coil command from said controller;
o a third switching means in a parallel configuration with a fourth switching means for a first auxiliary trip coil and a second auxiliary trip coil of a circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and
o fifth switching means in a parallel configuration with a sixth switching means for a first close coil and a second close coil of a circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller,
each of the switching means being provided with a NO/NC relay in series.
13. A common controller for single make single pole gas circuit breaker, said controller
comprising:
a. multi-phase close feedback means from close coils of said circuit breaker, one line of
each phase from a three phases supply are provided as input for said multi-phase close
feedback means;
b. multi-phase trip feedback means from trip coils' switching assembly, one line of each
phase from a three phases supply are provided as input for said multi-phase trip
feedback means;
c. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said
circuit breaker through said controller;
d. external pole discrepancy protection means adapted to receive inputs from at least one of
each of said lines across a three phase supply which is given to said multi-phase close
feedback means and to said multi-phase trip feedback means;
e. external tripping means adapted to provide external signals in order to provide trip
signals through said controller; and
f. switching assembly adapted to provide switching signals for actuation for each of said
main trip coils, said auxiliary trip coils, and said close coils based on received signals.

14. A common controller for multiple gas circuit breakers as claimed in claim 13 wherein, said controller comprising intra-pole timers, logic wiring, and external trip command in order to provide external tripping.
15. A common controller for multiple gas circuit breakers as claimed in claim 13 wherein, said controller comprising input means adapted to input 3-phase grid voltage and 3-phase grid current.
16. A common controller for multiple gas circuit breakers as claimed in claim 13 wherein, said controller comprising input means adapted to input analog inputs, digital inputs, station supply inputs, command inputs by a user and feedback inputs so that a computational mechanism of said controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil, close coil, or auxiliary tripping coil along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
17. A common controller as claimed in claim 13 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored.
18. A common controller as claimed in claim 13 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored, said controller means adapted to monitor power frequency current and voltage waveform.
19. A common controller as claimed in claim 13 wherein, said controller comprising a point-on-wave sensing mechanism adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions.
20. A common controller as claimed in claim 13 wherein, said controller comprising input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for main trip coil;

mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
21. A common controller as claimed in claim 13 wherein, said switching assembly comprising a
first switching system for a single phase of a single make single pole gas circuit breaker,
said first switching system comprising:
• first switching means for a main trip coil of said circuit breaker, said first switching means adapted to receive first trip command from said controller;
• second switching means for an auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
• third switching means for a first close coil of said circuit breaker, said third switching means adapted to receive close command from said controller.
22. A common controller as claimed in claim 13 wherein, said switching assembly comprising a
first switching system for a single phase of a single make single pole gas circuit breaker,
said first switching system comprising:
- first switching means in a parallel configuration with a second switching means for a main trip coil of said circuit breaker, said first switching means and said second switching means adapted to receive first trip command from said controller;
- third switching means in a parallel configuration with a fourth switching means switching means for an auxiliary trip coil of said circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and
fifth switching means in a parallel configuration with a sixth switching means for a close coil of said circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller.
23. A common controller for two make single pole gas circuit breaker, said controller
comprising:

A. multi-phase close feedback means from close coils of said circuit breaker, one line of -
each phase from a three phases supply are provided as input for said multi-phase close
feedback means;
B. multi-phase trip feedback means from trip coils' switching assembly, one line of each
phase from a three phases supply are provided as input for said multi-phase trip
feedback means;
C. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said
circuit breaker through said controller;
D. external pole discrepancy protection means adapted to receive inputs from at least one of
each of said lines across a three phase supply which is given to said multi-phase close
feedback means and to said multi-phase trip feedback means;
E. external tripping means adapted to provide external signals in order to provide trip
signals through said controller; and
F. switching assembly adapted to provide switching signals for actuation for each of said
main trip coils, said auxiliary trip coils, and said close coils based on received signals.
24. A common controller for multiple gas circuit breakers as claimed in claim 23 wherein, said controller comprising intra-pole timers, logic wiring, and external trip command in order to provide external tripping.
25. A common controller for multiple gas circuit breakers as claimed in claim 23 wherein, said controller comprising input means adapted to input 3-phase grid voltage and 3-phase grid current.
26. A common controller for multiple gas circuit breakers as claimed in claim 23 wherein, said controller comprising input means adapted to input analog inputs, digital inputs, station supply inputs, command inputs by a user and feedback inputs so that a computational mechanism of said controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil, close coil, or auxiliary tripping coil along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.

27. A common controller as claimed in claim 23 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored.
28. A common controller as claimed in claim 23 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored, said controller means adapted to monitor power frequency current and voltage waveform.
29. A common controller as claimed in claim 23 wherein, said controller comprising a point-on-wave sensing mechanism adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions.
30. A common controller as claimed in claim 23 wherein, said controller comprising input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for main trip coil; mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
31. A common controller as claimed in claim 23 wherein, said switching assembly comprising a first switching system for a single phase of a two make single pole gas circuit breaker, said first switching system comprising:

• first switching means for a main trip coil of said circuit breaker, said first switching means adapted to receive first trip command from said controller;
• second switching means for an auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
• third switching means for a first close coil of said circuit breaker, said third switching means adapted to receive close command from said controller.

32. A common controller as claimed in claim 23 wherein, said switching assembly comprising a
first switching system for a single phase of a two make single pole gas circuit breaker, said
first switching system comprising:
- first switching means in a parallel configuration with a second switching means for a main trip coil of said circuit breaker, said first switching means and said second switching means adapted to receive first trip command from said controller; third switching means in a parallel configuration with a fourth switching means switching means for an auxiliary trip coil of said circuit breaker, said third switching means and said fourth switching means adapted to receive second trip command from said controller; and
fifth switching means in a parallel configuration with a sixth switching means for a close coil of said circuit breaker, said fifth switching means and said sixth switching means adapted to receive close command from said controller.
33. A common controller for four make double pole gas circuit breaker, said controller
comprising:
I. multi-phase close feedback means from close coils of said circuit breaker, one line of each phase from a three phases supply are provided as input for said multi-phase close feedback means; II. multi-phase trip feedback means from trip coils' switching assembly, one line of each phase from a three phases supply are provided as input for said multi-phase trip feedback means;
III. intra-pole discrepancy monitoring adapted to monitor intra-pole discrepancy in said circuit breaker through said controller;
IV. inter-pole discrepancy monitoring adapted to monitor inter-pole discrepancy in said circuit breaker through said controller;
V. external pole discrepancy protection means adapted to receive inputs from at least one of each of said lines across a three phase supply which is given to said multi-phase close feedback means and to said multi-phase trip feedback means; VI. external tripping means adapted to provide external signals in order to provide trip signals through said controller; and

VII. switching assembly adapted to provide switching signals for actuation for each of said main trip coils, said auxiliary trip coils, and said close coils based on received signals.
34. A common controller for multiple gas circuit breakers as claimed in claim 33 wherein, said controller comprising intra-pole timers, logic wiring, and external trip command in order to provide external tripping.
35. A common controller for multiple gas circuit breakers as claimed in claim 33 wherein, said controller comprising input means adapted to input 3-phase grid voltage and 3-phase grid current.
36. A common controller for multiple gas circuit breakers as claimed in claim 33 wherein, said controller comprising input means adapted to input analog inputs, digital inputs, station supply inputs, command inputs by a user and feedback inputs so that a computational mechanism of said controller is adapted to take the plurality of input signals into account in order to firstly decide actuation criteria of main tripping coil, close coil, or auxiliary tripping coil along with time of actuation or time delay in actuation or the like parameters which effect an appropriate working of the circuit breaker assembly.
37. A common controller as claimed in claim 33 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored.
38. A common controller as claimed in claim 33 wherein, said controller comprising a point-on-wave sensing mechanism adapted to control switching of circuit breaker at particular point on current wave, as monitored, said controller means adapted to monitor power frequency current and voltage waveform.
39. A common controller as claimed in claim 33 wherein, said controller comprising a point-on-wave sensing mechanism adapted to determine point-on-wave switching parameters for a given electrical supply in relation to determined loads and previous load conditions.

40. A common controller as claimed in claim 33 wherein, said controller comprising input means adapted to receive input parameters selected from a group of input parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for main trip coil; mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for auxiliary trip coil mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; voltage parameters, station supply input parameters, analog input parameters, digital input parameters, command input parameters, feedback input parameters, 3-phase grid voltage input parameters, and 3-phase grid current input parameters.
41. A common controller as claimed in claim 33 wherein, said switching assembly comprising a second switching system for a single phase of four make double pole gas circuit breaker, said system comprising:
first switching means for a first main trip coil as well as a second main trip coil, said first switching means adapted to receive first trip coil command from said controller; second switching means for a first auxiliary trip coil and a second auxiliary trip coil of said circuit breaker, said second switching means adapted to receive second trip command from said controller; and
third switching means for a first close coil and a second close coil of a circuit breaker, said third switching means adapted to receive close command from said controller;
each of said first, second, and third switching means being provided with a NO/NC relay in
series.
42. A common controller as claimed in claim 33 wherein, said switching assembly comprising a
second switching system for a single phase of four make double pole gas circuit breaker,
said system comprising:
o first switching means in a parallel configuration with a second switching means for a first main trip coil as well as a second main trip coil, said first switching means and said second switching means adapted to receive first trip coil command from said controller;
o a third switching means in a parallel configuration with a fourth switching means for a first auxiliary trip coil and a second auxiliary trip coil of a circuit breaker, said third

switching means and said fourth switching means adapted to receive second trip
command from said controller; and o fifth switching means in a parallel configuration with a sixth switching means for a first
close coil and a second close coil of a circuit breaker, said fifth switching means and
said sixth switching means adapted to receive close command from said controller, each of the switching means being provided with a NO/NC relay in series.