Compared with traditional relay protection devices, microcomputer relay protection devices have the characteristics of microcomputer technology, strong calculation, analysis, and logical judgment capabilities, storage and storage functions, and can realize any perfect and complex protection principle. Microcomputer relay protection devices have great advantages in reliability, functional scalability, and process structure conditions. It has strong comprehensive analysis and judgment capabilities, and can achieve automatic error correction, which is difficult to achieve with traditional simulation protection, that is, automatic identification and elimination of interference to prevent misoperation caused by interference. At the same time, microcomputer relay protection devices have the characteristics of strong self diagnostic ability, convenient and flexible use, simple debugging and maintenance, low power consumption, and small size.

 

Daily inspection and maintenance of microcomputer relay protection device

 

1. Check the appearance of the microcomputer protection device, whether there are any abnormalities on the back of the module, whether the LCD display is normal, whether the wiring is loose or detached, and whether there are any abnormal phenomena such as heating, odor, smoke, etc.

 

2. Check the operation status and monitoring of the microcomputer protection device, such as whether the voltage and current data collected by the microcomputer relay protection tester are correct, and whether the three phases are balanced; Whether the input of the switch status of the device conforms to the actual situation, such as the position of the energy storage mechanism, the splitting position of the circuit breaker, the opening position of the grounding knife, the distance control position of the operating handle, etc.

 

3. Check whether the positions of each operating handle and rotary switch on the screen of the microcomputer protection device are correct; Is there any abnormal signal in the microcomputer protection device, such as whether the device sends out a trip or alarm signal? If there is a fault signal, the cause should be identified in a timely manner.

 

4. Check the setting value of the microcomputer protection device to determine whether it is consistent with the given value, check whether the input of setting current and voltage and time limit values is correct, and whether the input of the hard voltage board and soft voltage board conforms to the logical relationship of fixed values.

 

5. Check the action report records of the microcomputer protection device.

 

Periodic calibration of microcomputer relay protection devices:

 

To ensure the reliable operation of microcomputer protection devices, regular power outage verification should be carried out on relay protection devices and secondary circuits. The verification period is usually one year, and the main contents are:

 

1. Test the insulation resistance of the secondary circuit.

 

2. Use a relay protection tester to input standard current and voltage analog quantities, and verify the current and voltage sampling accuracy and power angle of the microcomputer protection device.

 

3. Verify whether the local or remote control operation buttons of the microcomputer protection device can work properly.

 

4. According to the protection setting sheet, use a relay protection tester to input simulated action values for the secondary protection action test of the switch group. Verify the reliability of the device's operation and whether the logical relationship of the constant value protection action meets the requirements of the constant value sheet;

 

Common faults in microcomputer relay protection devices:

 

1. Protection action issue. ① When a fault occurs, the protective device does not operate or operates reliably, making it impossible to quickly remove the fault When no faults occur, the protective device may be mistakenly activated.

 

2. The device panel buttons malfunction, the display screen is blurry, dim, or black with no display, the module plug-in is damaged, the display data is incorrect, and the device on/off switch is incorrect.

 

3. Fixed value issue. Mainly including: ① Setting calculation errors due to failure to provide accurate calculation parameters and drawing information to the protection calculation personnel. ② Wrong reading of values, TA and TV ratio calculation error. ③ Errors caused by human factors such as finding the wrong position in the microcomputer protection menu, using the fixed value area, and switching the protection pressure plate back and forth.