Valve type arrester operation, maintenance and troubleshooting - News - Global IC Trade Starts Here Free

1. Inspection and inspection during operation of valve type arrester

1. Check the surface condition of the arrester porcelain sleeve. In daily operation, the contamination of the surface of the porcelain sleeve of the arrester should be checked, because when the surface of the porcelain sleeve is seriously contaminated, the voltage distribution will be uneven. In a lightning arrester with parallel shunt resistors, when the voltage distribution of one of the components increases, the current through the shunt resistor will increase significantly, and the shunt resistor may be burned out to cause a malfunction. In addition, it may also affect the arc extinguishing function of the valve type arrester and reduce the protection characteristics of the arrester. Therefore, when the surface of the porcelain sleeve of the arrester is found to be seriously contaminated, it must be cleaned in time.

2. Check the lead wire of the arrester and the grounding down conductor for burn marks and broken strands, and whether the discharge recorder burns out. Through this inspection, it is easy to find the invisible defects of the arrester. Because under normal circumstances, after the lightning arrester is operated, the grounding down conductor and the recorder only pass the lightning current and the power frequency is small (usually 80A or less) and the time is very short (about 0.015). In addition to the change in the indicator number of the action recorder, there is generally no trace of burning. If, when there is a defect in the inner valve piece of the arrester or the arc cannot be extinguished, the amplitude and time of the continuous frequency of the power frequency passing through will increase, and the burnt mark will be generated at the connection point of the ground lead down line, or the discharge record will be made. The inside of the device burns black or burns out. When the above situation is found, immediately try to disconnect the arrester and conduct a detailed electrical inspection to avoid an accident.

3. Check if the seal at the upper end of the arrester is good. If the arrester is poorly sealed, it will cause accidents due to moisture ingress. Therefore, it should be checked whether the cement joints at the joint between the porcelain sleeve and the flange are tight. A waterproof cover can be added to the lead wire of the 10kV valve type arrester to prevent rainwater from penetrating.

4. Check whether the electrical distance between the lightning arrester and the protected electrical equipment meets the requirements. The arrester should be as close as possible to the protected electrical equipment.

5. The lightning arrester should check the operation of the recorder after the thunderstorm, whether there is any flashover discharge trace on the surface, whether the lead wire and the grounding down conductor are loose, and whether the arrester body has a swing.

6. Check the leakage current. When the power frequency discharge voltage is greater than or less than the standard value, it should be repaired and tested. When the discharge recorder has too many times of operation, it should be repaired; there is crack in the porcelain sleeve and cement joint; flange and rubber pad When it falls off, it should be replaced.

7. The insulation resistance of the arrester should be checked regularly. When measuring, apply 2500V insulation shaker, the measured value is compared with the previous result, and it can continue to be put into operation without obvious change. When the insulation resistance drops significantly, it is generally caused by poor sealing and moisture or short circuit of spark gap. When it is lower than the qualified value, it should be tested for characteristics. When the insulation resistance is significantly increased, it is generally due to poor contact of internal parallel resistance and Spring slack and separation of internal components.

8. In order to detect the invisible defects inside the valve arrester in time, a preventive test should be conducted before the annual thunderstorm season.

Second, valve type arrester abnormal phenomenon and fault handling

Valve type arresters often have abnormal phenomena and faults during operation, and should analyze and judge abnormal phenomena, and take measures to deal with faults in time.

1. If the weather is normal, the porcelain sleeve of the arrester is cracked. Stop the operation immediately, and the fault phase arrester will be taken out of operation and the qualified arrester will be replaced. In the thunderstorm, the porcelain sleeve is found to have cracks, and its operation should be maintained. After the thunderstorm has passed, the flashover is caused by the crack of the porcelain sleeve of the arrester, but the system is not grounded. The faulty phase arrester should be deactivated under possible conditions.
2. The inside of the arrester is abnormal or the casing is bursting. This phenomenon may cause system ground fault. When handling, personnel should not be close to the arrester. The fault arrester can be disconnected by circuit breaker or manual ground transfer.

3. The arrester suddenly explodes during operation, but the system has not been permanently grounded. After the thunderstorm, the isolation switch of the fault phase is opened, the arrester is deactivated and the qualified arrester is replaced in time. If the system has been permanently grounded after the explosion, it is forbidden to use the isolating switch to operate the arrester that has disabled the fault.

4. The lightning arrester action indicator burns black or burns inside, the grounding lead line connection point is blown, the arrester valve resistance is invalid, the spark gap arc extinguishing characteristic is deteriorated, the power frequency freewheeling is increased, and the above abnormal phenomena should be timely to the arrester For electrical test type disintegration inspection.

Third, the installation of valve type arrester

1. The installation position of the valve type arrester should be as close as possible to the protected equipment. The maximum electrical distance between the lightning arrester and the 3-10kV transformer in the thunderstorm season, the single incoming line is less than 15m, the double incoming line is less than 23m, and the three incoming lines are less than 27m. If it is greater than the above distance, the valve type arrester should be installed on each line.

2. The arrester should be installed vertically, not tilted, the leads should be connected firmly, and the terminals on the arrester should not be stressed.

3. In order to prevent its normal operation or failure after lightning strike, affecting the normal operation of the power system, the installation position of the arrester should be within the protection range of the drop-out fuse.

4. The lead section of the valve arrester should not be less than: copper wire 16mm2; aluminum wire 25mm2, the grounding down conductor and the metal casing of the protected equipment should be reliably connected to the grounding grid. For a single-type valve type arrester on the line, the grounding resistance of the grounding device is not more than 5Ω.