Arrester maintenance items
In order to avoid failure of the arrester in long-term operation, the arrester should be inspected regularly. The inspection items are as follows: 1. Measure the insulation resistance of the metal zinc oxide arrester and the base; 2. Measure the DC reference voltage of the metal zinc oxide arrester and 0.75 times the DC Leakage current under voltage; 3. Check the action of the discharge counter and the indication status of the ammeter; 4. Power frequency discharge voltage test.
Lightning arrester appearance inspection
In daily operation, check whether the appearance of the equipment is intact and whether the outer insulating surface is clean, because when the surface of the porcelain sleeve is seriously polluted, the voltage distribution will be very uneven. In the arrester with parallel shunt resistance, when the voltage distribution of one of the components increases, the current through its parallel resistance will increase significantly, which may burn out the parallel resistance and cause a fault. In addition, it may also affect the arc extinguishing performance of the valve arrester. Therefore, when the surface of the arrester porcelain sleeve is seriously dirty, it must be cleaned in time. Check the arrester for abnormal vibration, abnormal sound and odor. If there is, it should be stopped in time, and a detailed inspection and test should be carried out to avoid accidents.
Insulation resistance and grounding resistance measurement
Use a grounding resistance continuity tester to check whether the grounding lead of the arrester is in good condition, whether there are burn marks and broken strands, and whether the counter is intact. When measuring the insulation resistance of the arrester, use a 2500V insulation resistance meter. The measured value is compared with the previous result. When the change is not more than 5%, it can continue to be put into operation.
Discharge counter check
It is easy to find the hidden danger of the arrester by checking the discharge counter, because under normal operation and after the arrester acts, the power frequency freewheeling current with small lightning current and short time passes through the grounding lead and the counter, so in addition to the discharge counter In addition to the change of the indicated number, there is generally no trace of burning. Check the action of the arrester counter after a thunderstorm and make a record. Analysis of arrester readings equipped with on-line monitors for early detection of equipment defects and elimination of accidents in the bud. At the same time, check whether there are flashover discharge traces on the surface of the arrester, and whether the leads of each part are loose.
If there is any non-compliance on the basis of the above tests. When necessary, we can also measure the internal characteristics of the arrester, and use the DC high voltage generating device to detect the leakage current under 0.75 times. The leakage current value should not be greater than 50μA or close to the factory value.
In order to discover the internal defects of the arrester in time, a preventive test should generally be arranged before the thunderstorm season every year. When the leakage current, power frequency discharge voltage is greater than or less than the standard value and other electrical tests do not meet the requirements, the cause should be found and repaired.