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
Self learning system for point-on-wave switching of a circuit breaker
APPLICANT(S)
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR(S)
Namjoshi Yogendra of Crompton Greaves Ltd, CG Global R&D Centre, Crompton Greaves Limited, Kanjur Marg, Mumbai 400 042, Maharashtra, India; an Indian National.
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.
Still more particularly, this invention relates to the field of point-on-wave switching controllers for circuit breakers.
Specifically, this invention relates to a self learning system for point-on-wave switching of a circuit breaker.
BACKGROUND OF THE INVENTION:
The term switchgear, used in association with the electric power system, or substation 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 coii feat 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 circuit breakers of the prior art, the point-on-wave switching controllers for circuit breakers need to be calibrated for various compensations in factory and on-site. This means that a dual calibration is required. This required human intervention and equipment at both placed. The breaker timings also needs to be calibrated periodically (for example annually). Also, intelligence was localized to a controller of the circuit breaker system. Calibration parameters include, but are not limited to, the following parameters: 1) mechanical switching time parameter (delay) for close coil; 2) mechanical switching time parameter (delay) for trip coil; 3) mechanical response time to electrical signals; 4) SF6 pressure parameter; 5) air pressure parameter; 6) grid frequency; and 7) voltage parameters.
Inaccurate point-on-wave switching provides accurate and synchronous working of the circuit breaker.
Therefore, there is a need for a circuit breaker and associated controller which obviates the limitations of the prior art relating to dual calibration.
Therefore, there is a need for a self learning point-on-wave switching gas circuit breaker.
OBJECTS OF THE INVENTION:
An object of the invention is to provide calibration of point-on-wave switching parameters of a controller for switching of circuit breaker.
Another object of the invention is to provide automated calibration of point-on-

wave switching parameters for switching of circuit breaker.
Another object of the invention is to provide self-learning calibration of point-on-wave switching parameters for switching of circuit breaker,
Yet another object of the invention is to reduce calibration and recalibration times involved for a circuit breaker.
Still another object of the invention is to provide a relatively maintenance-free circuit breaker in terms of calibration and recalibration proceedings and mechanisms.
An additional object of the invention is to provide an 'intelligent' circuit breaker.
Another additional object of the invention is to provide calibration of point-on-wave switching parameters for switching of circuit breaker.
Another object of the invention is to provide automated calibration of point-on-wave switching, parameters for switching of circuit breaker.
Another object of the invention is to provide automated single calibration of point-on-wave switching parameters for switching of circuit breaker.
Yet another object of the invention is to provide automated calibration of point-on-wave switching parameters for switching of circuit breaker at accurate co-ordinates after two or more switching operations.

Still another object of the invention is to provide automated calibration of point-on-wave switching parameters for switching of circuit breaker taking into consideration all the parameters of the controller.
An additional object of the invention is to provide a feedback based automated calibration of point-on-wave switching parameters for switching of circuit breaker.
Another object of the invention is to provide a feedback based automatic calibration controller for point-on-wave tripping of trip coils of circuit breaker.
Yet another abject of the invention is to provide feedback based automatic calibration controller for point-on-wave closing of close coils of circuit breaker
Still another object of the invention is to provide a fail-safe feedback based automatic calibration for switching of circuit breaker.
An additional object of the invention is to provide self-learning point-on-wave switching circuit breaker adapted to achieve point-on-wave switching characteristics / parameters during charging of load without anticipating point-on-wave.
Yet an additional object of the invention is to achieve adaption in a self-learning point-on-wave switching circuit breaker to achieve point-on-wave switching characteristics / parameters.

Still an additional object of the invention is to achieve dynamic adaption in a self-learning point-on-wave switching circuit breaker to achieve point-on-wave switching characteristics / parameters.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a self learning system for point-on-wave switching of a circuit breaker, said system comprises:
a. at least a potential transformer, per phase, placed at the output of a load of
said circuit breaker, said potential transformer adapted to monitor transient
voltage parameters;
b. at least a current transformer, per phase, placed at the output of a load of a
circuit breaker, said current transformer adapted to monitor inrush current
parameters;
c. calibration parameters set-up mechanism adapted to set up at least one
calibration parameter;
d. threshold defining means adapted to define threshold parameter values for
each of the selected calibration parameters;
e. actuation means adapted to actuate said circuit breaker;
f. feedback means with inputs associated with each of the calibration
parameters that have been selected by said calibration set-up mechanism,
said feedback means associated with the 'charging' of load of the circuit
breaker and inputs from the at least a potential transformer and the at least a
current transformer, said feedback means adapted to further relay parameter
values through a feedback loop to said calibration set-up mechanism; and
g. processing means adapted to receive each threshold value for each
calibration parameter from the calibration parameters set-up mechanism and

the threshold defining means and further adapted to receive feedback parameter values, with respect to change in inrush current and change in transient voltage, at each switching cycle from the feedback means, thereby achieving adaptive-ness of circuit breaker actuation in order to achieve dynamic point-on-wave calibration characteristics.
Typically, said system 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 trip coil; mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; and voltage parameters.
Typically, said system includes parameter input means for said calibration set-up mechanism, said parameters selected from a group of parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for trip coil; mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; and voltage parameters.
Typically, said system includes threshold defining means adapted to define threshold parameter values for each of the selected calibration parameters, said threshold parameter values being determined by a human based on empirical data and the mechanical and electrical characteristics of the circuit breaker associated with said system.

Typically, said feedback means includes means to deduce changes in parameter values, by studying and learning from changes in inrush current as detected by the at least a current transformer and from changes in transient voltage as detected by the at least a potential transformer such that it deduces effect of air pressure on on-wave switching (from maximum to lockout minimum) and SF6 pressure through frequent operations keeping the operating coil-voltage the same.
Typically, said processing means includes means to process inputs in order to obtain optimum calibration parameter values, with respect to load charging, for each of the selected parameters whose feedback is being received during said switching cycles, and further adapted to intelligently obtain, iteratively, through repeated switching cycles, optimum parameter values of operation for the associated circuit breaker and controller in correlation with point-on-wave switching.
Typically, said processing means is a fuzzy logic based processing means.
Typically, said system includes communication means and channel adapted to download the calibration tables (which have calibrated parameter values) to a main controller.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic of the system.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a self learning system for point-of-wave switching of a circuit breaker.
Figure 1 illustrates a schematic of the system.
In accordance with an embodiment of this invention, there is provided at least a potential transformer (PT), per phase, placed at the output of a load of a circuit breaker intending to achieve point-on-wave parameters.
In accordance with another embodiment of this invention, there is provided at least a current transformer (CT), per phase, placed at the output of a load of a circuit breaker intending to achieve point-on-wave parameters.
The potential transformers and the current transformers receive inrush currents and voltage transients in order to monitor them and their characteristics.
According to the prior art systems and methodologies, the adaptive-ness was directed towards the load of the circuit breaker. Also, the adaptive-ness was to achieve switching at a proposed angle in degrees on a sinusoidal waveform.
According to this invention, the system and method is directed towards adaptive-ness towards the circuit breaker, itself, and switching adaptive-ness is not restricted to a proposed angle in degrees on a sinusoidal waveform.
The inrush currents and transient voltages may change load characteristics, breaker

characteristics, temperatures, and the like parameters, and hence, point-on-wave switching parameters change. Hence, it is important to monitor the inrush currents and transient voltages.
In accordance with an embodiment of this invention, there is provided a calibration parameters set-up mechanism (CSM) adapted to set up at least one calibration parameter from a group of calibration parameters in relation to circuit breaker (CKB) operation. The Calibration parameters include, but are not limited to, the following parameters: 1) mechanical switching time parameter (delay) for close coil; 2) mechanical switching time parameter (delay) for trip coil; 3) mechanical response time to electrical signals; 4) SF6 pressure parameter; 5) air pressure parameter; 6) grid frequency; and 7) voftage parameters.
In accordance with another embodiment of this invention, there is provided a threshold defining means (TDM) adapted to define threshold parameter values for each of the selected calibration parameters. The threshold parameter values may be determined by a human based on empirical data and the mechanical and electrical characteristics of the circuit breaker associated with the system and device of this invention.
In accordance with yet another embodiment of this invention, there is provided an actuation means (AM) adapted to actuate the circuit breaker through the system and device of this invention. The actuation of the circuit breaker will be dependent upon the calibrated parameters. In order to achieve the calibration, feedback (in terms of feedback operating values) needs to be obtained from the at least a potential transformer and at least a current transformer of the circuit breaker. The

actuation means is adapted to actuate / operate the circuit breaker through repeated more switching operations.
In accordance with yet another embodiment of this invention, there is provided a feedback means (FM) with inputs associated with each of the calibration parameters that have been selected by the calibration set-up mechanism, said feedback means associated with the 'charging' of load of the circuit breaker and inputs from the at least a potential transformer and the at least a current transformer. The feedback means relays parameter Values through a feedback loop to the calibration set-up mechanism. The feedback means deduces changes in parameter values, by studying and learning from changes in inrush current as detected 6y the at feast a current transformer and from changes in transient voftage as detected by the at least a potential transformer such that it deduces effect of air pressure on on-wave switching (from maximum to lockout minimum) and SF6 pressure through frequent operations keeping the operating coil-voltage the same.
In accordance with still another embodiment of this invention, there is provided a processing means (PM) adapted to. receive each threshold value for each calibration parameter from the calibration parameters set-up mechanism and the threshold defining means. Further, it is adapted to receive feedback parameter values, with respect to change in inrush current and change in transient voltage, at each switching cycle from the feedback means, the processing means is still further adapted to process these inputs in order to obtain optimum calibration parameter values, with respect to load charging, for each of the selected parameters whose feedback is being received during the switching cycles. Iteratively, through repeated switching cycles, the processing means is able to intelligently obtain

optimum parameter values of operation for the associated circuit breaker and controller in correlation with point-on-wave switching. The processing means is a fuzzy logic based processing means.
In accordance with an additional embodiment of this invention, there is provided a communication means and channel (CMC) adapted to download the calibration tables (which have calibrated parameter values) to a main controller (MC).
The following advantages can be cited, with the use of the system and method of this invention:
1. Easy maintenance through extension unit.
2. No human error or intervention.
3. Low requirement on skilled labour on-site.
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 self learning system for point-on-wave switching of a circuit breaker, said system comprising:
a. at least a potential transformer, per phase, placed at the output of a load
of said circuit breaker, said potential transformer adapted to monitor
transient voltage parameters;
b. at least a current transformer, per phase, placed at the output of a load
of a circuit breaker, said current transformer adapted to monitor inrush
current parameters;
c. calibration parameters set-up mechanism adapted to set up at least one
calibration parameter;
d. threshold defining means adapted to define threshold parameter values
for each of the selected calibration parameters;
e. actuation means adapted to actuate said circuit breaker;
f. feedback means with inputs associated with each of the calibration
parameters that have been selected by said calibration set-up
mechanism, said feedback means associated with the 'charging' of load
of the circuit breaker and inputs from the at least a potential transformer
and the at least a current transformer, said feedback means adapted to
further relay parameter values through a feedback loop to said
calibration set-up mechanism; and
g. processing means adapted to receive each threshold value for each
calibration parameter from the calibration parameters set-up mechanism
and the threshold defining means and further adapted to receive
feedback parameter values, with respect to change in inrush current and

change in transient voltage, at each switching cycle from the feedback means, thereby achieving adaptive-ness of circuit breaker actuation in order to achieve dynamic point-on-wave calibration characteristics.
2. A system as claimed in claim 1 wherein, said system 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 trip coil; mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; and voltage parameters.
3. A system as claimed in claim 1 wherein, said system includes parameter input means for said calibration set-up mechanism, said parameters selected from a group of parameters consisting of control signals parameters in relation to mechanical switching time parameter (delay) for close coil; mechanical switching time parameter (delay) for trip coil; mechanical response time parameter to electrical signals; SF6 pressure parameter; pressure parameter; grid frequency parameter; and voltage parameters.
4. A system as claimed in claim 1 wherein, said system includes threshold defining means adapted to define threshold parameter values for each of the selected calibration parameters, said threshold parameter values being determined by a human based on empirical data and the mechanical and electrical characteristics of the circuit breaker associated with said system.

5. A system as daimed in ciaim 1 wherein, said feedback means includes means to deduce changes in parameter values, by studying and learning from changes in inrush current as detected by the at least a current transformer and from changes in transient voltage as detected by the at least a potential transformer such that it deduces effect of air pressure on on-wave switching (from maximum to lockout minimum) and SF6 pressure through frequent operations keeping the operating coil-voltage the same.
6. A system as claimed in claim 1 wherein, said processing means includes means to process inputs in order to obtain optimum calibration parameter values, with respect to load charging, for each of the selected parameters whose feedback is being received during said switching cycles, and further adapted to intelligently obtain, iteratively, through repeated switching cycles, optimum parameter values of operation for the associated circuit breaker and controller in correlation with point-on-wave switching.
7. A system as claimed in claim 1 wherein, said processing means is a fuzzy logic based processing means.
8. A system as claimed in claim 1 wherein, said system includes communication means and channel adapted to download the calibration tables (which have calibrated parameter values) to a main controller.