FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A system for monitoring and controlling a circuit breaker.
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Prajapati Darshit, Kambli Upendra and Chaudhary Mukesh, all of Crompton Greaves Ltd, Electronic Development Centre, Global R&D Centre, Kanjurmarg, Mumbai - 400 042, Maharashtra, India, all Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
This invention relates to a system for monitoring and controlling a circuit breaker. BACKGROUND OF THE INVENTION
Typically, the opening and closing of a high voltage circuit breaker is controlled through a Control Switching Device which is configured to OPEN/CLOSE the circuit breaker at a pre-determined instance after receiving a signal to OPEN/CLOSE the circuit breaker from a user manually or automatically. The pre-determined instance is such that the OPENING/CLOSING of the circuit breaker coincides with a particular point on input line voltage/current wave, typically a zero or peak voltage/current point. This is called Point on Wave Switching. Point on Wave Switching ensures that minimum arc is created at the time of OPENING/CLOSING the circuit breaker thus stressing the arcing contacts to a minimum level thereby increasing the longevity of the circuit breaker contacts. Since the command to OPEN/CLOSE the circuit breaker is issued randomly by the user manually or automatically, the Control Switching Device first calculates and then implements the time delay (by known methods) in executing the open or close command. Since there are a number of operational parameters such as control voltage, air pressure, line frequency, SF6 gas pressure, temperature etc within the circuit breaker which can affect the opening or closing time of the circuit breaker, the Control Switching Device is pre-programmed to take into account such parameters and compensate them (by known methods) in calculating the final delay in issuing the OPEN/CLOSE command. Normally, primarily due to cost concerns, the Control Switching Device is not pre-programmed/configured to compensate all the operational parameters affecting the opening/closing of the circuit breaker. Such leads to inaccuracies in the calculation of the final delay time to be implemented in the issuance of the

OPEN/CLOSE command to the circuit breaker. Thus, an accurate Point on Wave Switching may not be achieved leading to an early wear and tear of the contacts of the circuit breaker. OBJECTS OF THE INVENTION
An object of the invention is to provide a system for monitoring and controlling a circuit breaker in which all operational parameters within the circuit breaker affecting the opening /closing time of the circuit breaker are compensated.
Another object of the invention is to calculate an accurate delay time for different variable parameters to be implemented in opening time/closing time of the circuit breaker.
Another object of the invention is to obtain an accurate Point on Wave Switching which improves the reliability of power grid.
Another object of the invention is to increase the life of the contacts of the circuit breaker. DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a system for monitoring and controlling a circuit breaker, the system comprising a processor based Control Switching Device configured to receive a signal to OPEN/CLOSE the circuit breaker, a plurality of sensors interfaced with the Control Switching device, each sensor being configured to measure operational parameter values within the circuit breaker, a storage module interfaced with Control Switching Device, an input means for inputting data sets into the storage module, each data set being a set of a operational parameter values and their corresponding time values which being the time taken by the contacts of the circuit breaker to CLOSE at the corresponding operational parameter value keeping the values of other operational parameter values within the circuit breaker rated, wherein the Control Switching Device, upon receiving a signal for OPENING/CLOSING the circuit breaker, is pre-

programmed to calculate a delay in issuing an OPENING/CLOSING command to the circuit breaker for achieving a Point on Wave Switching wherein the calculation of the delay involving compensating for alt parameters within the circuit breaker affecting the OPENING/CLOSING of the circuit breaker, the compensation of each parameter based on the corresponding data received from the corresponding sensor and/or corresponding data stored in the storage module,
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is a block diagram showing a system for monitoring and controlling a circuit breaker.
As shown in Fig 1. a system for monitoring and controlling a circuit breaker comprises of a processor based Control Switching Device 1. a plurality of sensors 2, an input means 3 and a storage module 4. The Control Switching Device 1 is usually a digital signal processor (DSP) based device. The Control Switching Device 1 is configured to receive signals/data to OPEN/CLOSE the circuit breaker from a user through a device such as switch or a fault management system or through another Control Switching Device. The Control Switching Device1 is a/so configured to receive signafs/data from externa/ devices interfaced therewith such as sensors 2, storage modules 4 and process the data based on pre-fed algorithms therein to output a command signal. Typically, the storage module 4 is a memory provided either within the Control Switching Device 1 or externally and interfaced with the control switching device 1. The sensors 2, input means 3 and the memory 4 if provided externally to the Control Switching Device 1 are interfaced with the Control Switching Device 1 in a known way and depending on type of the Control Switching Device 1 and the devices being interfaced therewith. Each sensor 2

is configured to sense/measure an operational parameter within the circuit breaker such as control voltage of the circuit breaker, air pressure within the circuit breaker. SF6 gas pressure within the circuit breaker, line frequency of the power grid, temperature within the circuit breaker and idle time of the circuit breaker. Within the storage module 4 data sets are fed/stored through the input means 3 pertaining to each operation parameter of the circuit breaker such as the control voltage, air pressure, line frequency, SF6 gas pressure, temperature, and idle time of the circuit breaker. Each data set is usually determined experimentally and comprises of the different values of the operational parameter and the corresponding time taken by the circuit breaker to OPEN/CLOSE with the other operational parameters kept rated. For example, for the parameter - control voltage within the circuit breaker, the data set is 5v - 5 msec, 6v - 6 msec, 7v - 7msec etc wherein the time values is the time taken by the circuit breaker to OPEN/CLOSE and determined experimentally keeping the other operational parameters rated within the circuit breaker. In addition to data sets corresponding to operational parameters sensed/measured by the sensor 2, other data sets such as pre-arcing time and re-ignition free window corresponding to relevant operational parameters are also stored within the storage module.
Each time the Control Switching Device 1 receives a signal to OPEN/CLOSE the circuit breaker, the Control Switching Device 1 is pre-programmed to issue a control signal to the relay coils connected to the moving contacts of the circuit such that the OPENING/CLOSING coincides at a particular instance on the input wave voltage called the Point on Wave Switching. Usually, the particular instance is at the peak/zero point of the input voltage/current wave, Because of Point on Wave Switching, minimum arc is generated in the circuit breaker at the time of OPENING/CLOSING of the contacts of the circuit breaker thus reducing the stress on the contacts during OPENING/CLOSING and hence increasing the longevity thereof. To achieve the

Point on Wave Switching, the Control Switching Device 1 has to invariably delay the issuance of the OPEN/CLOSE signal. The Control Switching Device 1 is pre-programmed, through well known algorithms/methods, to delay the issuance of the OPEN/CLOSE signals. However, since the above mentioned operational parameters affect the OPENING/CLOSING of the circuit breaker, it is necessary to compensate for them in the calculation of the delay to achieve an accurate Point on Wave Switching. The Control Switching Device 1 is pre-programmed, through well know algorithms/methods, for such a compensation. For example, to compensate the Control Voltage of the circuit breaker, the Control Switching Device 1 is pre-programmed to first fetch the control voltage detected by the sensor 2, say 5v. Subsequently, the corresponding time value, say 5 msec, is fetched from the storage module 4. Finally, the time value 5 msec is subtracted/added from the total delay time calculated depending upon the algorithm. Similarly, all the operational parameters are compensated. For operational parameters such as re-ignition free window and pre-arcing time not measurable by the sensor, their time value is taken from the storage module and subtracted/added from the delay time calculated so far to arrive at the final delay time. Finally, from the peak/zero of the next cycle of the input voltage/current wave, the final delay time as calculated above is implemented in the issuance of the OPEN/CLOSE command to achieve Point on Wave Switching.
According to the invention, an accurate Point on Wave Switching is achieved by compensating all parameters affecting the opening/closing time of the circuit breaker such as control voltage, air pressure, line frequency, SF6 gas pressure, temperature, idle time, re-ignition free window and pre-arcing time.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the

disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim:
1. A system for monitoring and controlling a circuit breaker, the system comprising
a. a processor based Control Switching Device configured to receive a signal to
OPEN/CLOSE the circuit breaker;
b. a plurality of sensors interfaced with the Control Switching device, each sensor
being configured to measure operational parameter values within the circuit
breaker;
c. a storage module interfaced with Control Switching Device;
d. an input means for inputting data sets into the storage module, each data set being a set of a operational parameter values and their corresponding time values which being the time taken by the contacts of the circuit breaker to CLOSE at the corresponding operational parameter value keeping the values of other operational parameter values within the circuit breaker rated; wherein the Control Switching Device, upon receiving a signal for OPENING/CLOSING the circuit breaker, pre-programmed to calculate a delay in issuing an OPENING/CLOSING command to the circuit breaker for achieving a Point on Wave Switching wherein the calculation of the delay involving compensating for all parameters within the circuit breaker affecting the OPENING/CLOSING of the circuit breaker, the compensation of each parameter based on the corresponding data received from the corresponding sensor and/or corresponding data stored in the storage module.
2. The system as claimed in cJaim 1, wherein the operational parameters being control voltage of the circuit breaker, air pressure within the circuit breaker, SF6 gas pressure within the circuit breaker, line frequency of power grid, temperature within the circuit

breaker, idle time of the circuit breaker, re-ignition free window of the circuit breaker and pre-arcing time within the circuit breaker.
3. The system as claimed in claim 1, wherein the signal to Control Switching Device to OPEN/CLOSE the circuit breaker is from a user through a device such as a switch or another Control Switching Device.
4. The system as claimed in claim 1, wherein the Control Switching Device is based on a digital signal processor.
5. The system as claimed in claim 1, wherein the storage module is a memory device.
6. The system as claimed in claim 1, wherein the storage module is provided within the Control Switching Device and interfaced therewith.
7. The system as claimed in claim 1, wherein the storage module is provided externally to the Control Switching Device and interfaced therewith.
8. The system as claimed in claim 1, wherein the input means is a keyboard.