Claims:1. A testing method (200) for a high voltage circuit breaker (CB), the method (200) comprising the steps of:
electrically coupling (202) contacts on both sides of the CB to earth during the testing such that an earth loop is created between the CB and the earth;
opening (204) the contacts of the earthed CB and supplying, by a current source (302), a predefined current through the opened CB,
measuring/sampling (206), by a measuring/sampling unit, a first current flowing through the earth loop when the predefined current is supplied to the open CB, wherein the first current is calculated by measuring a voltage drop across a part of the earth section;
closing (208) the contacts of the earthed CB and supplying, by the current source (302), the predefined current through the closed CB;
measuring/sampling (210), by the measuring/sampling unit, a second current flowing through the earth loop, and total current and voltage across the CB contacts, from a time of initiating the closing of the CB to complete closing of the CB; and
processing (212), by a processing unit (304), the first current and the second current through the earth path, and the total current and the voltage across the closed CB, to compensate the current flowing through the earth loop and correspondingly determining any or a combination of the actual current flowing through the contacts of the CB, CB closing time with number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
2. The method (200) as claimed in claim 1, wherein the voltage drop across the part of the earth section used for measuring the first current flowing through the earth loop, is calculated by pre-determining a resistance of the corresponding part of the earth loop keeping the CB open.

3. The method (200) as claimed in claim 1, wherein the method (200) comprises the step of generating, by the processing unit (304), a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB.
4. The method (200) as claimed in claim 1, wherein the method (200) comprises the step of converting, by a signal processing unit (304) operatively coupled to the measuring unit and the CB, the first current, the second current, the total current, and the voltage drop being sampled/measured by the measuring unit into a set of signals that are compatible with the processing unit (304).
5. A testing system (300) for a high voltage circuit breaker (CB), the system (300) comprising:
a measuring unit configured with the CB, wherein both sides of contacts of the CB are earthed during the testing to create an earth loop, the measuring unit is configured to:
measure/sample, when the CB contacts are open, a first current flowing through the earth loop upon supplying a predefined current to the CB, and correspondingly generate a first set of signals, wherein the first current is calculated by measuring a voltage drop across a part of the earth section; and
measure/sample, from a time of initiating the closing of the CB to complete closing of the CB, a second current flowing through the earth loop, and total current and voltage across the CB contacts upon supplying the predefined current to the CB, and correspondingly generate a second set of signals; and
a processing unit (304) operatively coupled to measuring unit and the CB, the processing unit (304) comprising one or more processors coupled to a memory storing instructions executable by the processors to:
receive the first set of signals and the second set of signals from the measuring unit, and correspondingly extract the first current, the second current, the total current, and the voltage across the closed CB; and
process the first current, the second current, the total current, and the voltage across the closed CB to compensate the current flowing through the earth loop and correspondingly determine any or a combination of the actual current flowing through the contacts of the CB, CB closing time with number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
6. The system (300) as claimed in claim 5, wherein the system (300) comprises a current source (302) to supply the predefined current of 100A and/or 200A to be injected through the CB, and wherein the current source (302) comprises an internal shunt resistance to facilitate measurement of the total current flowing through the CB.
7. The system (300) as claimed in claim 5, wherein the processing unit (304) is configured with a breaker analyzer (312) to generate a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB.
8. The system (300) as claimed in claim 5, wherein the measuring/sampling unit comprises: a set of current sensors to measure any or a combination of the first current and the second current flowing through the earth loop, and the total current flowing through the CB; and a voltage sensor to measure the voltage across the CB, and
wherein the voltage drop across the part of the earth section used for measuring the first current flowing through the earth loop, is calculated by pre-determining a resistance of the corresponding part of the earth loop keeping the CB open.
9. The system (300) as claimed in claim 5, wherein the system (300) comprises a set of amplifiers (306) and signal conditioning circuits (308) being configured between the measuring/sampling unit and the processing unit (304), wherein the set of amplifiers (306) and signal conditioning circuits (308) are configured to convert the first set of signals and the second set of signals generated by the measuring unit into a third set of signals that is compatible with the processing unit (304), and remove noise from the sampled signals.
10. The system (300) as claimed in claim 9, wherein the system (300) comprises an analog to digital converter (ADC) (310) configured between the signal conditioning circuits (308) and the processing unit (304) to convert the analog form of the third set of signals into a digital form that is readable and processible by the processing unit (304).
, Description:TECHNICAL FIELD
[0001] The present disclosure relates to the field of circuit breaker testing systems. More particularly the present disclosure relates to a simple, efficient and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] The circuit breaker is one of the most critical components in high voltage power systems. For performance analysis of a circuit breaker, contact open, close, and close-open timings of the circuit breaker are measured. Also, the nature of dynamic contact resistance during close-open operation is analyzed. Generally, to test the circuit breaker, it must be isolated from high voltage from both ends. For human safety, before making any connection to the circuit breaker contacts, breaker contacts are required to be earthed from both ends.
[0004] In the existing method of testing circuit breakers, after making the connection to the breaker contacts, earthing of breaker contacts is removed. This is done because earthing on both ends shorts the breaker contacts and it makes it impossible to measure the opening and closing timings of contacts with both ends short. The tests can be conducted by this traditional test method in which the operator’s safety is not guaranteed.
[0005] A high voltage circuit breaker (110KVA to 765KVA) is a three-phase switch required and provided in the high voltage transmission lines and at power stations. As circuit breaker is switching complex load at very high voltage (up to 765kV) and at very high current (up to thousands of amperes), the operational performance of high voltage circuit breaker is very important. To ensure its performance, various parameters such as main contact timings, contact gap, contact travel characteristics, coil currents, static/dynamic contact resistance, auxiliary contact timing are measured and monitored on a regular basis to conform with reliability.
[0006] Out of all parameters, main contact timing and static/dynamic contact resistance values play critical roles in ensuring circuit breaker healthiness. To find out contact timings, traditionally, voltage sensing method is used. In this method, constant DC voltage is applied at one end of contact and sensed at another end. The applied voltage will be available at the other end of contact when the circuit closes. Thus, it is possible to know the status of the circuit breaker by sensing voltage at another end. Similarly, for dynamic contact resistance measurement 100 or 200 A DC current is injected through the contact, and voltage drop across contact is read and calculated dynamically changing resistance of breaker contact during operation. During testing, the circuit is completely isolated from the incoming and outgoing sides. But due to induced voltage from nearby charged lines, there is the voltage available in the contacts. This voltage may be in a few kV.
[0007] In the existing testing method, to bypass this voltage to earth, both sides of breaker contacts are earthed immediately after isolating the circuit breaker from both ends. Now as both ends are earthed, the circuit breaker contacts are always in shorted condition. In such conditions, it is not possible to sense the circuit breaker contact status with the voltage sensing method. In this case, the earth connections to the circuit breaker are removed after making the connection to the testing instrument and in the testing instrument, a low impedance path to the earth is provided to bypass the induced voltage to earth. Thus, in the existing method of testing circuit breaker, the earth connections from both the ends of the circuit breaker need to be removed, before starting the test.
[0008] The connection sequence of the existing method includes steps of taking shutdown by opening the circuit breaker, isolating the circuit breaker from both the ends by opening the disconnectors from both ends, connecting earthing to both ends either by connecting Earth switches in the system or by connecting manual earth and making the connections of test instruments to the breaker such that the breaker contacts will be earthed through the low impedance path in the test instrument. Further, the method includes the steps of removing the earth switch or manual earthing connected to the breaker contact, carrying out testing of the circuit breaker, again connecting the earth switch or manual earthing from both sides of the circuit breaker, removing the connections of the test instruments, removing earth switch or manual earth. Furthermore, the method includes the steps of connecting the disconnectors to the circuit breaker contacts to bring the circuit breaker in line, and closing the circuit breaker to charge the line.
[0009] However, in the existing method of testing circuit breakers, it is not possible to find out breaker timings and contact resistance by keeping both sides earth connected. Besides, the circuit breaker tester needs to follow the connection sequence, in which there are chances of mistakes. These mistakes can lead to dangerous safety consequences, so the tester needs to be always alerted during testing.
[0010] In addition, as there is a mechanical interlock between the disconnector and earth switch, the earth switch can not be connected to the line when disconnectors are in the closed position. Earth switches can be operated only when disconnectors are opened. Similarly, If, the earth switch is closed (Connected to breaker contacts), the disconnectors cannot be closed. This arrangement is made considering the safety of the testing person and equipment. As a result, in the existing method of testing, the testing person needs to disconnect the earth switch during testing. This creates the possibility of closing the disconnector connected to the breaker. So, by mistake, someone can close the disconnector during testing. This can apply high voltage to the testing instrument and can cause a severe accident that may be leading to the death of persons involved in testing.
[0011] Further, when the connection to the test instrument is done and earth switches are opened, the induced voltage on the circuit breaker contacts is bypassed to the earth through the low impedance path provided in the instrument to the earth. This makes the earth connection of the testing instrument very critical. The earth connected to the instrument has to be firm and should not be accidentally disconnected during testing. If the earth connection gets disconnected, it becomes very dangerous for the person operating the instrument.
[0012] This frequent connection & disconnection of earthing and the need to follow the correct sequence of the same could lead to human error having grave consequences. There have been incidences of severe accidents due to this. Working with both sides earthed continuously during maintenance, without the need of the above-referred connection/disconnection provides for much safer operation and is recommended by authorities & standardization organizations.
[0013] Thus, testing the circuit breaker by removing earth from both sides can be dangerous, but no alternative is available in the art.
[0014] There is, therefore, a need to overcome the above drawback, limitations, and shortcomings associated with existing testing solutions, and provide a simple, efficient and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process.

OBJECTS OF THE PRESENT DISCLOSURE
[0015] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0016] It is an object of the present disclosure to overcome the above-mentioned drawbacks, limitations, and shortcomings associated with existing circuit breaker testing solutions.
[0017] It is an object of the present disclosure to provide a testing method for circuit breakers in which the tester (testing personnel) remains always safe and the tester is not required to remain alert always during the testing.
[0018] It is an object of the present disclosure to provide a testing method for circuit breakers in which there is no need to disconnect earth switches during testing, thereby eliminating any possibility of closing the disconnector by mistake or harming nearby people and equipment.
[0019] It is an object of the present disclosure to overcome noise present in the earth path while testing the circuit breakers.
[0020] It is an object of the present disclosure to provide a method of identifying the current passing through the earth path by measuring drop across a part of the earth section and using it to compensate the current during actual testing.
[0021] It is an object of the present disclosure to find out breaker timings and dynamic contact resistance measurement of circuit breaker by keeping both sides of the circuit breaker earth connected.
[0022] It is an object of the present disclosure to measure Closing time, Opening time C-O time, Number of bounces, and bounce duration, keeping earth switches of both sides of contacts in closed condition during circuit breaker testing.
[0023] It is an object of the present disclosure to measure and generate a DCRM graph of circuit breaker contacts.
[0024] It is an object of the present disclosure to provide a simple, efficient and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process.

SUMMARY
[0025] The present disclosure relates to a simple, efficient and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process.
[0026] In the proposed method, a high current source is used to detect the change in contact status by compensating the current flowing through the earth path. When the test is started, a high current up to 100 A may be passed through the circuit breaker. Accordingly, the current starts flowing through the earth loop, if breaker contacts are open. The current through the earthing path may be sampled and kept for compensation during the closing of contacts. Then a close command may be issued to the circuit breaker. During the operation, when the circuit breaker is closed, the current passing through the earth path, total current, and voltage drop across the breaker contact may also be sampled. A processing unit may process the sampled data to compensate for the current flowing through the earth and find out the actual current flowing through breaker contacts. Then using these current samples and voltage drop samples, the breaker closing time with accurate bounces and bounce duration may be calculated. In the same way, breaker opening time can also be calculated.
[0027] The proposed method may also be used with 100A or 200A current source to carry out the DCRM test. The 100A or 200 A current may be passed through the circuit breaker. As the circuit breaker is in open condition, the total current passes through the earth loop. This current passing through the earth is sampled and kept as a reference signal for further compensation of current during the actual operation of the circuit breaker. Then C-O command may be executed on the circuit breaker. During the operation, the current passing through the earth path, total current, and voltage drop across the breaker contact may be sampled. After the operation, the processing unit may process the sampled data to properly compensate the earth currently and actual DC current passing through breaker contacts and resistance graph with all the variations are plotted as DCRM graph.
[0028] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0029] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. The diagrams are for illustration only, which thus is not a limitation of the present disclosure.
[0030] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[0031] FIG. 1 illustrates an exemplary working principle of the proposed method for testing the circuit breakers, in accordance with an embodiment of the present disclosure.
[0032] FIG. 2 illustrates the exemplary steps involved in the proposed method, in accordance with an embodiment of the present disclosure.
[0033] FIG. 3 illustrates an exemplary block diagram of the proposed system for testing the circuit breakers, in accordance with an embodiment of the present disclosure.
[0034] FIG. 4 illustrates an exemplary simulated setup of the circuit breaker, in accordance with an embodiment of the present disclosure.
[0035] FIG. 5A illustrates an exemplary flow chart of the DCRM measurement process performed by the processing unit, in accordance with an embodiment of the present disclosure.
[0036] FIG. 5B illustrates an exemplary flow chart of the contact timing measurement process performed by the processing unit, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0037] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0038] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some.
[0039] Embodiments of the present disclosure relate to a simple, efficient, and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of circuit breaker are possible by earthing the contacts from both ends during the entire test process.
[0040] According to an aspect, the present disclosure elaborates upon a testing method for a high voltage circuit breaker (CB). The method comprising the steps of electrically coupling contacts on both sides of the CB to earth during the testing such that an earth loop is created between the CB and the earth, followed by another step of opening the contacts of the earthed CB and supplying, by a current source, a predefined current through the opened CB, measuring/sampling, by a measuring/sampling unit, a first current flowing through the earth loop when the predefined current is supplied to the open CB. The first current is calculated by measuring a voltage drop across a part of the earth section. The method further comprises the steps of closing the contacts of the earthed CB and supplying, by the current source, the predefined current through the closed CB, followed by measuring/sampling, by the measuring/sampling unit, a second current flowing through the earth loop, and total current and voltage across the CB contacts, from a time of initiating the closing of the CB to complete closing of the CB. Further, the method comprises the step of processing, by a processing unit, the first current, and the second current through the earth path, and the total current and the voltage across the closed CB, to compensate the current flowing through the earth loop and correspondingly determining any or a combination of the actual current flowing through the contacts of the CB, CB closing time with the number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
[0041] In an embodiment, the voltage drop across the part of the earth section used for measuring the first current flowing through the earth loop is calculated by pre-determining a resistance of the corresponding part of the earth loop keeping the CB open.
[0042] In an embodiment, the method comprises the step of generating, by the processing unit, a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB.
[0043] In an embodiment, the method comprises the step of converting, by a signal processing unit operatively coupled to the measuring unit and the CB, the first current, the second current, the total current, and the voltage drop being sampled/measured by the measuring unit into a set of signals that are compatible with the processing unit.
[0044] According to another aspect, the present disclosure elaborates upon a testing system for a high voltage circuit breaker (CB). The system comprises a measuring unit configured with the CB, wherein both sides of contacts of the CB are earthed during the testing to create an earth loop. The measuring unit is configured to measure/sample, when the CB contacts are open, a first current flowing through the earth loop upon supplying a predefined current to the CB, and correspondingly generate a first set of signals. The first current is calculated by measuring a voltage drop across a part of the earth section. The measuring unit further measures/samples, from a time of initiating the closing of the CB to complete closing of the CB, a second current flowing through the earth loop, and total current and the voltage across the CB contacts upon supplying the predefined current to the CB, and correspondingly generate a first set of signals. The system comprises a processing unit operatively coupled to the measuring unit and the CB. The processing unit comprises one or more processors coupled to a memory storing instructions executable by the processors to receive the first set of signals and the second set of signals from the measuring unit and correspondingly extract the first current, the second current, the total current, and the voltage across the closed CB. The processing unit processes the first current, the second current, the total current, and the voltage across the closed CB to compensate the current flowing through the earth loop and correspondingly determine any or a combination of the actual current flowing through the contacts of the CB, CB closing time with a number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
[0045] In an embodiment, the system comprises a current source to supply the predefined current of 100A and/or 200A to be injected through the CB. The current source comprises an internal shunt resistance to facilitate the measurement of the total current flowing through the CB.
[0046] In an embodiment, the processing unit is configured to generate a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB.
[0047] In an embodiment, the measuring/sampling unit comprises a set of current sensors to measure any or a combination of the first current and the second current flowing through the earth loop, and the total current flowing through the CB contacts; and a voltage sensor to measure the voltage across the CB contacts. Further, the voltage drop across the part of the earth section used for measuring the first current flowing through the earth loop is calculated by pre-determining a resistance of the corresponding part of the earth loop keeping the CB open.
[0048] In an embodiment, the system comprises a set of amplifiers and signal conditioning circuits being configured between the measuring/sampling unit and the processing unit. The set of amplifiers and signal conditioning circuits are configured to convert the first set of signals and the second set of signals generated by the measuring unit into a third set of signals that is compatible with the processing unit and remove noise from the sampled signals.
[0049] In an embodiment, the system comprises an analog to digital converter (ADC) configured between the signal conditioning circuits and the processing unit to convert the analog form of the third set of signals into a digital form that is readable and processible by the processing unit.
[0050] Referring to FIG. 1, the working principle of the present invention is disclosed. In an exemplary embodiment, 100A or 200A (but not limited to the likes) current source can be used to inject the current through the circuit breaker (CB). The source has an internal shunt to measure the total current flowing through the circuit breaker (CB). Herein, C1 is the total current flowing through the circuit. When the circuit breaker is in open condition, then all possible current (supplied by current source) flows through the earthing loop (also referred to as earth path or earth loop, herein). Further, C2 is the current flowing through the earthing path. The current C1 flowing the earthing path can be determined by measuring a voltage drop across a part (P) of the earth section as shown in the figure, which can be calculated by pre-determining a resistance of the corresponding part P of the earth loop keeping the CB open.
[0051] When a close command is issued to the circuit breaker, during closing operation, the current supplied by the current source will be divided between the circuit breaker and earthing loop. As the contact resistance is less (in the range of few micro-ohms) as compared to earth resistance (in the range of milliohms to ohms), a major part of the current will flow through breaker contacts. But still, a considerable amount of current will flow through the earth loop also.
[0052] Further, sampling of C1, C2 as well as voltage drop (V1) across the breaker contacts is started just before giving a close command to the breaker. The sampling of C1, C2, and V1 are continued during the operation of the circuit breaker. The sampling is stopped after a few milliseconds once the breaker is completely closed.
[0053] After the operation, the analysis on sampled data can be done and compensation of current through the earth loop can be carried out on the sampled data. This is done by a processing unit such as but not limited to a microcontroller, microprocessor, and a computer. Accordingly, using the compensated current data and sampled voltage drop (V1) data, the data for change in resistance of contact can be generated. This can be plotted as a DCRM graph.
[0054] Furthermore, the same process can be followed with a smaller current for calculating the closing and opening time of the circuit breaker.
[0055] Referring to FIG. 2, the proposed testing method 200 for a high voltage circuit breaker is disclosed. Method 200 can include step 202 of earthing the contacts by electrically coupling contacts on both sides of the CB to earth during the testing such that an earth loop is created between the CB and the earth. Further, method 200 can include step 204 opening the contacts of the earthed CB and supplying, by a current source, a predefined current such as 100A or 200A and the likes through the opened CB. Furthermore, method 200 can include step 206 of measuring/sampling, by a measuring/sampling unit, a first current flowing through the earth loop when the predefined current is supplied to the open CB.
[0056] In an embodiment, the first current (or current flowing through the earth loop) can be calculated by measuring a voltage drop across a part P of the earth section as shown in FIG. 1. The voltage drop across the part of the earth section used for measuring the first current flowing through the earth loop can be calculated by determining the resistance of the corresponding part of the earth loop keeping the CB open prior to the testing. The value of the resistance and the voltage drop across the part/section of the earth can help determine the current flowing through the earthing loop based on Ohm’s Law.
[0057] Method 200 can further include step 208 of closing the contacts of the earthed CB and supplying, by the current source, the predefined current through the closed CB. Further, method 200 can include step 210 of measuring/sampling, by the measuring/sampling unit, a second current flowing through the earth loop, and total current and voltage across the CB contacts, from a time of initiating the closing of the CB to complete closing of the CB. Furthermore, method 200 can include step 212 of processing, by a processing unit, the first current, and the second current through the earth path, and the total current and the voltage across the closed CB, to compensate the current flowing through the earth loop and correspondingly determining any or a combination of the actual current flowing through the contacts of the CB, CB closing time with the number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
[0058] In an embodiment, the method 200 can include the step of generating, by the processing unit, a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB
[0059] Referring to FIG. 3, in an embodiment, the proposed system 300 for testing a high voltage circuit breaker is disclosed. The system 300 can include a measuring unit configured with the CB. The measuring unit can include a set of current sensors to measure the current flowing through the earth loop, and the total current flowing through the CB. The measuring unit can include a voltage sensor to measure the voltage across the CB. Further, system 300 can include a processing unit 304 in communication with the sensors or measuring unit to receive and process the data sampled by the measuring unit. Furthermore, a current source 302 can be operatively coupled to the processing unit 304 and the circuit breaker. The current source 304 can supply a predefined current of 100A and/or 200A or less, to be injected through the CB. The current source 304 can include an internal shunt resistance to facilitate the measurement of the total current flowing through the CB.
[0060] Initially, the CB contacts can be kept open. Herein, the measuring unit can be configured to measure/sample, the current (first current) flowing through the earth loop upon supplying a predefined current (100 A or 200A) to the CB, and can correspondingly generate and transmit a first set of signals to the processing unit 304. In an embodiment, the first current can be calculated by measuring a voltage drop across a part of the earth section, which can be calculated by pre-determining a resistance of the corresponding part of the earth loop keeping the CB open.
[0061] Further, the closing of the CB can be initiated and the same predefined current can be supplied to the CB. Herein, the measuring unit can be configured to measure/sample a second current flowing through the earth loop, and total current and voltage across the CB contacts from a time of initiating the closing of the CB to complete closing of the CB and can correspondingly generate and transmit a second set of signals to the processing unit 304.
[0062] In an embodiment, the system 300 can include a set of amplifiers 306-1, 306-2 (collectively referred to as amplifier 306, herein) and a set of signal conditioning circuits 308-1 to 308-2 (collectively referred to as signal conditioning circuit 308, herein) being configured between the measuring/sampling unit and the processing unit 304. The set of amplifiers 306 and signal conditioning circuits 308 can be configured to convert the first set of signals and the second set of signals generated by the measuring unit into a third set of signals that is compatible with the processing unit 304.
[0063] The signal conditioning circuits 304 can include filters to remove noise from the sampled signals. Further, system 300 can include an analog to digital converter (ADC) 310 configured between the signal conditioning circuits and the processing unit 304 to convert the analog form of the third set of signals (provided by the signal processing circuits 308) into a digital form that is readable and processible by the processing unit 304.
[0064] In an embodiment, the processing unit 304 can include one or more processors coupled to a memory storing instructions executable by the processors. The processing unit 304 can receive the first set of signals and the second set of signals from the measuring unit, and can correspondingly extract the first current, the second current, the total current, and the voltage across the closed CB. Further, the processing unit 304 can process the first current, the second current, the total current, and the voltage across the closed CB to compensate for the current flowing through the earth loop. Furthermore, the processing unit 304 can determine any or a combination of the actual current flowing through the contacts of the CB, CB closing time with the number of bounces and bounce duration, CB operating time, and resistance of the CB contacts.
[0065] In an embodiment, the processing unit 304 can be configured to generate a dynamic contact resistance measurement (DCRM) graph depicting the change in the resistance of the CB contacts as a function of time during the testing of the CB. The system 300 can include a breaker analyzer 312 comprising a display unit that can be in communication with the processing unit 304 through serial communication means 314 and the likes. The processing unit 304 can transmit the DCRM graph, and the actual current flowing through the contacts of the CB, CB closing time with the number of bounces and bounce duration, CB operating time, and resistance of the CB contacts, to the breaker analyzer 312, which can be processed by the breaker analyzer 312 to display it on the display unit.
[0066] Referring to FIG. 4, an exemplary simulated setup of the proposed system of FIG. 3 to establish the working principle of FIG. 1 is disclosed. To establish the above working principle, the required hardware prototype was developed. As illustrated in FIG. 3 and 4, the circuit breaker was simulated with a low rating Contactor. Both ends of contactor contacts were connected to earth and experimentations were carried out on this simulated setup in the lab.
Hardware
[0067] An add-on prototype hardware module was developed which can be interfaced with the existing circuit breaker analyzer 312. Firstly, a 100A current source 302 was developed using the latest technology Supercapacitors. Supercapacitors are used mainly to reduce the weight of the power source and to avoid the usage of lead-acid batteries for the current generation. Further, three analog channels were designed to sample data of C1 (Total Current in the circuit), C2 (Current through Earth path), and V1 (Drop across the contacts. All the analog signals were conditioned and given to the 24-bit high-speed analog to digital converter (ADC) 310. The digitally converted data is then fed to the microcontroller (processing unit 304).
[0068] Here a local microcontroller was used as the processing unit 304 to sample analog data at high speed, to communicate with the breaker analyzer 312, and to control the current source 302. Once the start signal was received from the breaker analyzer 312, the microcontroller 304 started the current source 302. 100 A current was passed through the breaker contacts and all three analog channels were sampled at high speed and stored in the internal memory of the microcontroller 304.
[0069] After finishing the data sampling, the data was sent to the breaker analyzer 312. The processing engine of the breaker analyzer 312 further ran the algorithms on sampled data to compensate for the current in the earth loop and find out closing, opening times and DCRM graphs.
[0070] Once the setup of FIG. 4 was ready, the contactor setup was made to simulate the circuit breaker in a lab. As illustrated in FIG. 4, out of three phases, one phase contact was used to simulate the circuit breaker condition. Using a C-K clamp, 100A current was injected through the contacts. Both the ends were shorted with a long cable and connected to the earth to simulate both sides of earth condition. Further, a copper shunt was used in series with this shorting cable, to measure current in the earthing path. A communication cable was connected between add-on measuring module and the circuit breaker analyzer. When the contactor was operated from the analyzer, the module started the current injection and sampling the total current C1, Current through earth loop C2, and the voltage drop across the contact V1, and sent this data to the breaker analyzer.
Data Analyzing and Processing
[0071] For the measurement of contact timing and DCRM, DC current was passed through the circuit. But the earth generally remains influenced by the 50 or 60 Hz signal, due to system voltage and this signal may get mixed with the DC current. Part of this unwanted AC signal was filtered through the signal conditioning circuits 308 of the hardware or system 300. The processing unit 304 also consisted of powerful AC noise and high-frequency noise-suppressing algorithms being executable by the processors of the processing unit 304. After studying the nature of variation in the current signal and its behavior during breaker operation in different conditions, proper current compensation was developed and validated. This algorithm derives the only current flowing through the breaker contacts after doing compensation on each current sample.
[0072] Once the data samples for actual current flowing through the contact were derived, the bounces in closing operation were calculated by analyzing the voltage drop across the contact and current signal nature. It is also possible to find the exact closing time of the circuit breaker.
[0073] In the same way, processing unit 304 made it possible to calculate the opening as well as Close-Open time. As with this setup and algorithm, it is possible to separate the current flowing through contacts, and the voltage drop across the contact is available. Further, the DCRM graph was also plotted in a normal way. The general flowchart of software algorithms is shown in FIGs. 5A and 5b.
[0074] The experimentation was done on the contactor setup of FIG. 4 and closing and opening time of contactor were calculated by earthing both sides of contacts as well as without earthing both sides and the results were found comparable.
[0075] Therefore, the present invention overcomes the drawbacks, limitations, and shortcomings associated with existing testing solutions, and provide a simple, efficient and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process, thereby eliminating any possibility of harming nearby people and equipment
[0076] Besides, the present disclosure also provides a method of identifying the current passing through the earth path by measuring the voltage drop across a part of the earth section, which was not done by any of the prior arts and using it to compensate the current during actual testing of the circuit breaker.
[0077] It is to be appreciated by a person skilled in the art that while various embodiments and drawings of the present disclosure elaborate upon the use of a 100A or 200A current source, however, the proposed system can be implemented with the current source of different ratings as well, based on the rating of the circuit breaker to be tested, and all such embodiments are well within the scope of the present disclosure.
[0078] In an aspect, processing unit 304 of the proposed system 300 may comprise one or more processor(s). The one or more processor(s) may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, logic circuitries, and/or any devices that manipulate data based on operational instructions. Among other capabilities, one or more processor(s) are configured to fetch and execute computer-readable instructions stored in a memory of the system 300. The memory may store one or more computer-readable instructions or routines, which may be fetched and executed to create or share the data units over a network service or the breaker analyzer 312. The memory may comprise any non-transitory storage device including, for example, volatile memory such as RAM, or non-volatile memory such as EPROM, flash memory, and the like.
[0079] System 300 may also comprise an interface(s). The interface(s) may comprise a variety of interfaces, for example, interfaces for data input and output devices, referred to as I/O devices, storage devices, and the like. The interface(s) may facilitate communication of system 300. The interface(s) may also provide a communication pathway for one or more components of the system 300. Examples of such components include, but are not limited to, processing engine(s) and database.
[0080] The processing engine(s) may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement one or more functionalities of the processing engine(s). In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the processing engine(s) may be processor-executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the processing engine(s) may comprise a processing resource (for example, one or more processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement the processing engine(s). In such examples, system 300 may comprise the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to system 300 and the processing resource. In other examples, the processing engine(s) may be implemented by electronic circuitry.
[0081] The database may store the data sampled by the measuring unit as well as the data processed by the processing unit 304. Further, the stored data may be used by the breaker analyzer 312 for processing and displaying.
[0082] Embodiments of the present invention include various steps, which will be described below. The steps may be performed by hardware components or may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor programmed with the instructions to perform the steps. Alternatively, steps may be performed by a combination of hardware, software, firmware and/or by human operators.
[0083] Embodiments of the present invention may be provided as a computer program product or mobile application, which may include a machine-readable storage medium tangibly embodying thereon instructions, which may be used to program a computer (or other electronic devices) or mobile devices, to perform a process. The machine-readable medium may include, but is not limited to, fixed (hard) drives, magnetic tape, floppy diskettes, optical disks, compact disc read-only memories (CD-ROMs), and magneto-optical disks, semiconductor memories, such as ROMs, PROMs, random access memories (RAMs), programmable read-only memories (PROMs), erasable PROMs (EPROMs), electrically erasable PROMs (EEPROMs), flash memory, magnetic or optical cards, or other type of media/machine-readable medium suitable for storing electronic instructions (e.g., computer programming code, such as software or firmware).
[0084] Moreover, in interpreting the specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[0085] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0086] The proposed invention overcomes the above-mentioned drawbacks, limitations, and shortcomings associated with existing circuit breaker testing solutions.
[0087] The proposed invention provides a testing method for circuit breakers in which the tester (testing personnel) remains always safe and the tester is not required to remain alert always during the testing.
[0088] The proposed invention provides a testing method for circuit breakers in which there is no need to disconnect earth switches during testing, thereby eliminating any possibility of closing the disconnector by mistake or harming nearby people and equipment.
[0089] The proposed invention finds out breaker timings and contact resistance of circuit breakers by keeping both sides of the circuit breaker earth connected.
[0090] The proposed invention overcomes noise present in the earth path while testing the circuit breakers.
[0091] The proposed invention provides a method of identifying the current passing through the earth path by measuring drop across a part of the earth section and using it to compensate the current during actual testing
[0092] The proposed invention measures Closing time, Opening time C-O time, Number of bounces, and bounce duration, keeping earth switches of both sides of contacts in closed condition during circuit breaker testing.
[0093] The proposed invention measures and generates a DCRM graph of circuit breaker contacts.
[0094] The proposed invention provides a simple, efficient, and safe system and method for testing of a high voltage circuit breaker in which all the performance tests of the circuit breaker are possible by earthing the contacts from both ends during the entire test process.