A) TECHNICAL FIELD

[0001] The present invention generally relates to timers for operating relays and more particularly to microcontroller based selective relay timers used for testing meters, switching devices like circuit breakers etc.

B) BACKGROUND OF THE INVENTION

[0002] The circuit breakers constitute an important and critical component in the electric power system. The circuit breakers play a key role in protecting the equipment and personnel from damage due to unwanted heavy current passing through the circuit. There are many reasons to maintain and test a circuit breaker. Friction and wear can affect the performance and the efficiency of the moving contact elements in the circuit breaker. Leaks may occur in the valves and in the seals used in the arc extinguishing chambers, damping devices pneumatic and hydraulic operating mechanisms. The fault may occur in electrical control circuits thereby deteriorating the contact surfaces of interrupters and bus bar joints to increase the risk of excessive heat generation.

[0003] Because of their key role, the circuit breakers are periodically tested. One of the earliest and most successful test methods is the timing test, which consists of measuring the mechanical operation time of the breakers contacts. Timing tests will always be important to prevent damages to a circuit breaker, Incorrect operation of the circuit breaker can have of disastrous consequences on the equipment or the substation personnel.

[0004] Different measuring devices are used to measure the operation time of the circuit breakers. The first generation testing devices are based on oscillographic mode of record curves and currently not in use. The second generation testing methods are based on digital timers with time pulse conversion. Generally the commercially produced timers for testing circuit breakers are expensive.

[0005] The testing of circuit breakers is very important operation. The circuit breaker is to be tested and maintained regularly so that it keeps working properly. The best way to ensure safe operation of the circuit breakers is through the correct selection and setting of the relays that control them. A correct coordination ensures during the generation of problems that the right circuit breaker is opened to correct the problem. The testing of a circuit breaker involves injecting signals into relay circuit that simulate various kinds of faults and checking the circuit breaker operation. This procedure may include testing of the relays and testing after establishing the setting adjustments. Most of the protective relays are analog devices. However, several manufacturers have developed microprocessor based protective relays that include the tripping functions required to protect the interconnection. In order to fulfill most of these requirements, the relays and several associated timers are used in the past to protect the circuit breakers.

[0006] The timer relay has been provided to allow emergency shut-down in the event of failure of the pressure switches. The microprocessor based relays are well known. The microprocessor based relay is a mini computer with preset programming which uses inputs from the analog-digital cards, digital inputs, communications, and other external devices. The digital signals are analyzed by the microprocessor using algorithms to determine the operational parameters, pick up, and timing based on settings provided by the user. AU these tasks are controlled by the algorithms, and each task can be represented by one line of computer code.

[0007] The analog timers are currently used for load changeover and control in protection units. The earlier timers used for programming the ON and OFF time cannot be used for selecting the number of relays required to energize and test the contacts in the circuit breakers. Moreover none of the prior art devices provides a simple method of selecting the timers during the testing of the circuit breakers. Hence there is a need to develop an automatic system and method to select the number of relays during the testing of the circuit breakers.

[0008] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

C) OBJECTS OF THE INVENTION

[0009] The primary object of the present invention is to develop a microcontroller based selective relay timer for testing the switching devices, meters etc.

[0010] Another object of the present invention is to develop a microcontroller based selective relay timer for selecting the number of relays for operation with given ON and OFF time intervals.

[0011] Yet another object of the present invention is to develop a microcontroller based selective relay timer to provide a profile with preset ON and OFF time sequence for operating the selected relays during the testing of the circuit breakers or meters.

[0012] Yet another object of the present invention is to develop a microcontroller based selective relay timer provided with a visual display to indicate the running stage or sequence during the testing of the circuit breakers or meters.

[0013] Yet another object of the present invention is to develop a microcontroller based selective relay timer with a Personal Computer (PC) based monitoring capability.

[0014] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D) SUMMARY OF THE INVENTION

[0015] The various embodiments of the present invention provide a Microcontroller based Selective Relay Timer (MC-SRT) to select and operate the desired number of relays in a desired operating sequence to test a circuit breaker or a meter. According to one embodiment of the present invention, the device has a microcontroller system connected to plurality of relays and light emitting diodes. An input device is connected to the microcontroller system to input the programming parameters and to select a stored program sequence. A display module is connected to the microcontroller system to exhibit a graphical user interface to provide a display menu to enable a user to input and change the programming parameters and to select a stored program sequence for operating the relays. The microcontroller system is programmed to select and operate the relays in a preset sequence. A personal computer is connected to the system to input the program parameters into the microcontroller remotely. The light emitting diodes provide a visual indication to show the relays that are under operation,

[0016] According to one embodiment of the present invention, the microcontroller based selective relay timer is provided with pluralities of relays that are used for switching. The microcontroller receives inputs such as number of relays. ON time, and OFF time from a user. Based on the inputs, the required number of relays in the timer are selected and operated in a sequence specified with the input ON and OFF time for preset interval of time to test the circuit breaker. The test output results are stored in a memory.

[0017] The microcontroller enables the user to select the number of relays for operation, along with the user inputs such as ON and OFF time. The microcontroller also helps the user to program or input a profile with given ON and OFF time sequence so that the selected relays are operated based on the input or programmed profile. The microcontroller also enables the user to program the following parameters like load ON time, load OFF time, number of relays and profile. Based on the selected sequence, the microcontroller based selective relay timer programmed with all the other parameters is operated. The microcontroller based selective relay timer may be used with any other external signals or load combination for testing meters, after the programming of the microcontroller.

[0018] Based on the objective and the nature of test to be performed, the user can program the microcontroller based selective relay timer with parameters such as type of profile, number of relays, load ON time, load OFF time etc. The microcontroller is operated after the completion of the programming operation to execute the input sequence or profile. The user can input parameters such as profile selection, relay count, ON time and OFF time.

[0019] The microcontroller based timer is very compact and easy to handle. Since the whole operation is controlled by microcontroller it is more accurate. The display such as Liquid Crystal Display (LCD) enables the user to visualize running sequence.

The memory such as Electrically Erasable Programmable Read-Only Memory (EEPROM) enables the permanent storage of the input values so that the values will remain in the memory even during a power failure period. The microcontroller can be programmed several times according to user convenience.

[0020] According to one embodiment of the present invention, a method is provided to select the relays in the timer to test the circuit breaker using a microcontroller. After the initialization of the microcontroller ports, the pressing of the relevant keys is checked. When the relevant keys are pressed, the internal memory such as EEPROM of the microcontroller is cleared. Then a programming mode is displayed. The microcontroller waits for preset time such as 1 minute to receive any user inputs. When the user inputs the data like load ON time, load OFF time and relay count etc., with in the given time, then the microcontroller is activated to operate the selected number relays based on an input sequence including the ON time and OFF time continuously to test the circuit breaker and the results are stored in the memory. The microcontroller is provided with a display like LCD to indicate the running sequence or stage.

[0021] When the input from the user is not received within the given time, then the internal memory of the microcontroller is read for the stored data related to the operating sequence of the timer. When the stored data related to the operating sequence of the relays is found, the relays are operated based on the stored data to test the circuit breaker. When the stored data related to the operating sequence of the relays in the timer is not found, the relays are operated based on the default setting sequence.

E) BRIEF DESCRIPTION OF THE DRAWINGS:

[0022] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

[0023] FlG.l illustrates a block diagram of a Microcontroller based Selective Relay Timer (MC-SRT) device according to one embodiment of the present invention.

[0024] FIG.2 illustrates an example of a program sequence or profile executed in MC-SRT for operating relays for testing devices according to one embodiment of the present invention.

[0025] FIG.3 illustrates another example of program sequence or profile executed in MC-SRT for operating relays for testing devices according to one embodiment of the present invention.

[0026] F1G.4 illustrates an example of default program sequence or profile executed in MC-SRT for operating relays for testing devices according to one embodiment of the present invention.

[0027] FIG 5 illustrates a flowchart explaining the operation of a MC-SRT according to one embodiment of the present invention.

[0028] FIG. 6 illustrates a circuit block diagram of a controller board in a MC-SRT according to one embodiment of the present invention.

[0029] FIG. 7 illustrates a circuit block diagram of a relay card board in a MC-SRT according to one embodiment of the present invention.

[0030] FIG. 8 illustrates a functional block diagram of a power supply board used in a MC-SRT according to one embodiment of the present invention.

F) DETAILED DESCRIPTION OF THE INVENTION

[0031] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[0032] The various embodiments of the present invention provide a microcontroller based selective relay timer for selecting the number of relays for operation with given ON and OFF time intervals. According to one embodiment of the present invention, the device has a microcontroller system connected to plurality of relays and light emitting diodes (LED). An input device is connected to the microcontroller system to input the programming parameters and to select a stored program sequence. For example, the input device is a key board. A display module is connected to the microcontroller system to exhibit a graphical user interface to provide a display menu to enable a user to input and change the programming parameters and to select a stored program sequence for operating the relays. For example, the display module may be a liquid crystal display (LCD) module. The programming parameters include type of profile, number of relays, load ON time and load OFF time. The microcontroller system is programmed to select and operate the relays in a preset sequence. The input parameters, the programming sequence and the result of testing operation are stored in the internal memory of the microcontroller.

[0033] A personal computer is connected to the system to input the program parameters into the microcontroller remotely. The light emitting diodes provide a visual indication to show the relays that are under operation.

[0034| According to one embodiment, the microcontroller based selective relay timer is provided with 8 relays that are used for switching. The microcontroller receives inputs such as number of relays, ON time, OFF time from a user. Based on the inputs, the required number of relays in the timer are selected and operated in a sequence specified with the input ON and OFF time for a preset interval of time to test the circuit breaker. The test output results are stored in a memory.

[0035] The microcontroller enables the user to select the number of relays for operation, along with the user inputs such as ON and OFF time. The microcontroller also helps the user to program or input a profile with given ON and OFF time sequence so that the selected relays are operated based on the input or programmed profile. The microcontroller also enables the user to program the following parameters like load ON time, load OFF time, number of relays and profile. Based on the selected sequence, the microcontroller based selective relay timer programmed with all the other parameters is operated. The microcontroller based selective relay timer may be used with any other external signals or load combination for testing meters, after the programming of the microcontroller.

[0036] Based on the objective and the nature of test to be performed, user can program the microcontroller based selective relay timer with parameters such as type of profile, number of relays, load ON time, load OFF time etc. The microcontroller is operated after the completion of the programming operation to execute the input sequence or profile. The user can input parameters such as profile selection, relay count, ON time and OFF time.

[0037] The microcontroller based timer is very compact and easy to handle. Since the whole operation is controlled by microcontroller it is more accurate. The display such as Liquid Crystal Display (LCD) enables the user to visualize running sequence. The memory such as Electrically Erasable Programmable Read-Only Memory (EEPROM) enables the permanent storage of the input values so that the values will remain in the memory even during a power failure period. The microcontroller can be programmed for many times according to user convenience.

[0038] According to one embodiment of the present invention, a method is provided to select the relays in the timer to test the circuit breaker using a microcontroller. After the initialization of the microcontroller, the pressing of the relevant keys is checked. When the pressing of the relevant keys are detected, the internal memory such as EEPROM of the microcontroller is cleared to store new input data or profile. Then a programming mode is displayed on the display module.

[0039] The microcontroller waits for preset time such as 1 minute to receive any user inputs such as pressing of a key and program parameter data like load ON time, load OFF time, relay count, etc. When a right key is pressed in the input device such as a key board, a graphical user interface is provided to enable the user to provide inputs like load ON time, load OFF time, relay count and an operating sequence etc. Then the selected operating sequence for the relays is executed by the microcontroller based on the received input programming parameters. The microcontroller is provided with a display like LCD to indicate the running sequence or stage. The LEDs indicate the relays under operation. The test results are stored in a memory and displayed on the LCD module.

[0040] When a left key is pressed in the input device such as a key board, the stored programming sequences in the internal memory of the microcontroller are read displayed. Afterwards a program mode is selected for operation from the displayed program modes for execution.

[0041] When the input from the user is not received within the given time, then the internal memory of the microcontroller is read for the stored data related to the operating sequence of the timer. When the stored data related to the operating sequence of the relays is found, the relays are operated based on the stored data to test the circuit breaker. When the stored data related to the operating sequence of the relays in the timer is not found, the relays are operated based on the default setting sequence.

[0042] FIG.l illustrates a block diagram of the Microcontroller based Selective Relay Timer (MC-SRT) according to one embodiment of the present invention. With respect to FIG. 1, the MC-SRT has a microcontroller 2 communicatively connected with the relays 4 to select and control the operations of relays 4. Pluralities of light emitting diodes (LED) 6 are connected in parallel to the relays 4 with the microcontroller 2 to indicate the relays 4 that are selected and are under service. The LCD module 10 is connected to the microcontroller 2 to provide a visual indication to display the running stage or sequence during the testing of the circuit breakers. An input device 8 such as a key board is connected to the microcontroller to input the programming parameters and to select a program sequence form the program sequences displayed on the LCD module 10. A personal computer (PC) 14 is connected to the microcontroller 2 through a universal synchronous asynchronous receiver transmitter (USART) 12 to provide the user inputs and to program the microcontroller remotely.

[0043] The input device 8 including the keys such as right key, left key, up key, down key and a reset (RST) key is connected to the microcontroller 2. The input device 8, for example, is a key board. The input device enables the user to provide input parameters such as profile selection, relay count, ON time and OFF time to the microcontroller 2. The relays 4 are connected with Light Emitting Diodes (LED) 6 which are used to indicate the operating condition of the relays 4.

[0044] The LCD 10 provides a graphical user interface to display a menu to enable the user to select the programming parameters and to select a stored programmed sequence. The user selects the desired parameter settings, changes the parameter settings and selects the program sequence using the keys provided in the input device

[0045] The microcontroller 2 is interfaced with a Personal Computer (PC) 14 through a Universal Synchronous Asynchronous Receiver Transmitter (USART) module 12.The microcontroller 2 receives the input parameters such as number of relays, ON time, OFF time from the user through the input device 8. Based on the input parameters, the microcontroller 2 selects the required number of relays from the relays 4 and operates the selected relays 4 in a sequence specified with the input ON and OFF time for preset interval of time to test the circuit breaker. Also, the microcontroller 2 provides the running stage or sequence via the LCD module 10 during the testing of the circuit breakers or meters.

[0046] FIG.2 illustrates an example of program sequence executed in the MC-SRT to select and operate the desired number of relays to test a device. With respect to FIG. 2, the user provides inputs such as ON time, OFF time, and number of relays for operation. In the given example, a tri-vector meter is tested with all phase inductive loads by injecting the externally generated noise or any other input signals. The user selects a programming sequence for operating the selected number of relays with given load ON time and load OFF time for a given test period. The externally generated noise and DC voltage are injected during every relay on time period or any other input signals. As per the selected program sequence, the selected number of relays are switched ON and switched OFF for the given load ON time and the load OFF time one by one. Each relay is operated and switched off successively. Thus all the relays are turned ON and OFF for the given test period successively and continuously.

[0047] As per the selected program sequence, in this example, only one relay is operated at one time and the rest of the relays are turned off Thus the relay-1 is only operated during load ON time first by the microcontroller while the remaining relays are not operated. Then the relay-1 is switched for the input load OFF time. Then the second relay is operated and turned off. Thus all the eight relays are operated and switched OFF successively and one by one. Then again all the eight relays are operated and turned off for the given load ON and OFF intervals until the test time is over. This process is continued for each selected relay during successive ON and OFF time intervals until the user resets the test operation manually or automatically.

[0048] FIG.3 illustrates another example program sequence executed in the MC-SRT to select and operate the desired number of relays to test a device. With respect to FIG. 3, the user has to input the number of relays for operation, ON time and OFF time. In the given example, two make contactors are tested using the selected profile and the program parameters. The two contactors are tested by switching the contactors and comparing the operation by selecting the relays. In this example the user selects a preset profile called sequence 2. Based on the selected sequence 2, all the selected relays 1-N are operated simultaneously for given load ON time and switched OFF simultaneously for the preset load OFF time. Then all the relays 1 -N are selected and operated again for the given load ON time simultaneously. Thus the relays are operated by switching ON and OFF the relays with the given time intervals for the preset time period selected for testing the contacts.

[0049] F1G.4 illustrates a default program sequence executed in MC-SRT according to one embodiment of the present invention. With respect to FIG. 4, the microcontroller operates the selected relays during ON and OFF time intervals based on a default setting sequence programmed in, when data related to the operating sequence of the relays are not found in internal memory of the microcontroller. Normally the micro controller checks for the program data stored in the internal memory, when a user input is not received within a preset time period. When a relevant data is not found in the memory, then the microcontroller executes an infinite loop sequence using input sequence mode, input load ON time, input load OFF time and number of relays. When the relevant data stored in the memory of the microcontroller is found, a default setting stored in the internal memory of the microcontroller is read and used to operate the relays to execute a test operation. The results of the test operation are stored in the internal memory of the micro controller for future reference.

[0050] FIG 5 illustrates a flowchart for sequence execution of MC-SRT according to one embodiment of the present invention. With respect to FIG. 5. the ports of the microcontroller are initialized (51). Then the pressing of the relevant keys is checked/detected (52). When the pressing of the relevant keys are detected, then the internal memory such as EEPROM of the microcontroller is cleared (53). Then a programming mode is displayed on a display like LCD (54). The microcontroller waits for a preset time such as 1 minute to receive inputs from a user. When a left key is pressed in the input device such as key board, then microcontroller receives the user inputs data like load ON time, load OFF time and relay count etc., through switches with in the preset time (55). Based on the received input data, the microcontroller is activated to operate the selected number relays based on an input sequence for the input load ON time and OFF time continuously to test the circuit breaker (56). The results are stored in the memory.

[0051] When a right key is pressed in the key board, the microcontroller skips the receiving of the user input data. The data stored in the memory corresponding to the previous settings are read from the internal memory of the computer and displayed (57).

[0052] The internal memory of the microcontroller is read to detect a data relevant to a desired program sequence for selecting and operating the relays (58). Then the selected numbers of relays are operated in a continuous or infinite loop using the selected program sequence, load ON time and load OFF time to test the circuit breaker/energy meter (59). When the relevant data corresponding to the desired program sequence is not found in the displayed program data, the relays are operated continuously using a default setting to test the circuit breakers/energy meters (60).

The progress and the result of the test operation are displayed on a display module like liquid crystal display (LCD). The results of the test operation are stored in the internal memory of the microcontroller.

[0053] FIG. 6 illustrates a block circuit diagram of a controller board used in the MC-SRT according to one embodiment of the present invention. With respect to FIG. 6, the controller board includes a microcontroller 2 which is connected to a set of relays 41-48 and a set of LEDs 61-68 through a driver for LEDs and relays 16. The set of relays (41-48) and LEDs (61-68) are connected in parallel. When a particular relay (41-48) is operated, the corresponding LED (61-68) is glown to indicate the operating status of the relay. A personal computer may be connected to the microcontroller 2 is connected through a USART 12 to enable the remote monitoring/programming of the microcontroller 2 and the remote input of programming parameters. A set of switches 81-84 provided in an input device are connected to the microcontroller 2 to enable a user to input programming parameters such as number of relays (41-48), ON time, and OFF time. The microcontroller 2 is further connected to a LCD display 10 to visualize running stage or sequence during the testing of the meters and the circuit breakers. During operation, the microcontroller 2 receives the input parameters such as the number of relays (41-48), ON time, OFF time from the user through the switches 81-84 or the USART 12. Based on the input parameters, the microcontroller 2 selects the required number of relays (41-48) from the relays 41-48 and operates the selected relays 41-48 and the appropriate LEDs 61-68 in a sequence specified with the input ON and OFF time for preset interval of time to test the meters and the circuit breakers. The running stage or sequence and the results of the test operation are visually indicated through the LCD display 10.

[0054] FIG. 7 illustrates a block circuit diagram of a relay card board used in the MC-SRT according to one embodiment of the present invention. With respect to FIG. 7, the relay card board includes a microcontroller 2 connected to a set of relays 41-48 through a driver for LEDs and relays. The LEDs are connected in parallel to the relays with a a driver for LEDs and relays 16. During operation, the microcontroller 2 selects the required number of relays from the relays 41-48 based on the input parameters, and operates the selected relays 41-48 and the corresponding LEDs in a sequence specified with the input ON and OFF time for preset interval of time to test the meters and the circuit breakers.

[0055] FIG. 8 illustrates a functional block diagram of a power supply board used in the MC-SRT according to one embodiment of the present invention. With respect to FIG. 8, a transformer 82 is connected to a 240V alternating current (AC) supply 81 to step down the voltage level. The out put of the transformer is passed through the two rectifier/fiUers 83, 85 to obtain 24V DC output (84) and 5V DC output (86) respectively. The 24V DC output (84) is fed to the driver for LED and relays while the 5V DC output is fed to the microcontroller.

G) ADVANTAGES OF THE INVENTION

[0056] Based on the objective and the nature of test to be performed, the user can program the microcontroller based selective relay timer with parameters such as type of profile, number of relays, load ON time, load OFF time, etc. The microcontroller is operated after the completion of the programming operation to execute the input sequence or profile. The user can input parameters such as profile selection, relay count, load ON time and load OFF time.

[0057] The microcontroller helps the user to program or input a profile with given load ON and OFF time sequence so that the selected relays are operated based on the input or programmed profile. Based on the selected sequence, the microcontroller based selective relay timer programmed with all the other parameters is operated. The microcontroller based selective relay timer may be used with any other external signals or load combination for testing meters, after the programming of the microcontroller.

[0058] The Programmable Interface Controller (PIC) based timer is very compact and easy to handle. Since the whole operation is controlled by PIC, the result is more accurate. The LCD display enables the user to visualize running sequence. The memory such as the EEPROM enables the permanent storage of the input values so that the values remain in the memory even during a power failure period. The microcontroller can be programmed for many times according to user convenience.

[0059] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, ail such modifications are deemed to be within the scope of the claims.
[0060] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be

CLAIMS

What is claimed is:

1. A micro controller based selective relay timer device comprising:

a microcontroller connected to plurality of relays and tight emitting diodes;

an input device connected to the microcontroller; and

a display module connected to the microcontroller;

wherein the microcontroller is programmed to select and operate the relays in a preset sequence.

2. The device according to claim 1, wherein the microcontroller is programmed to store plurality of operation sequences to select and operate the relays in a preset sequence to test a meter.

3. The device according to claim 1, wherein the input device is used to input the programming parameters and to select a stored program sequence.

4. The device according to claim I, wherein the input device is a key board.

5. The device according to claim 1, wherein the display module exhibits a graphical user interface to provide a display menu to enable a user to input and change the programming parameters and to select a stored program sequence for operating the relays.

6. The device according to claim 1, wherein the display module is a liquid crystal display module.

7. The device according to claim I further comprising a personal computer connected to the microcontroller to input the program parameters into the microcontroller remotely.

8. The device according to claim 1 wherein the light emitting diodes provide a visual indication to show the relays under operation.

9. The device according to claim 2, wherein the programming parameters include type of profile ,number of relays, load OFF time.