**Metal Oxide Surge Arrester Testing and Selection Scheme**
The selection and testing of metal oxide surge arresters are crucial for ensuring the safety and reliability of power systems. The following guidelines outline the recommended procedures and standards for various types of tests.
**Insulation Resistance Test**
This test is performed before the annual thunderstorm season and when necessary. For voltages above 35kV, the insulation resistance should be no less than 2500MΩ, while for 35kV and below, it should be no less than 1000MΩ. A megger rated at 2500V or higher should be used for the test.
**DC 1mA Voltage (U1mA) and Leakage Current at 0.75U1mA**
This test is also conducted before the annual thunderstorm season and when needed. The U1mA value must not be lower than the specified value in GB11032. The measured U1mA should not deviate by more than ±5% from the initial value or manufacturer’s specification. Additionally, the leakage current at 0.75U1mA should not exceed 50μA. During the test, ambient temperature, humidity, and the initial value should be recorded. A shielded wire should be used to measure the current accurately.
**AC Leakage Current at Operating Voltage**
This test is performed on newly installed 110kV and above arresters after three months of operation, every six months thereafter, and once a year before the thunderstorm season. It involves measuring the full current and resistive current at operating voltage, or power loss. If there is a significant change compared to the initial value, increased monitoring is required. If the resistive current doubles, an inspection should be carried out immediately. Environmental conditions such as temperature, humidity, and operating voltage should be recorded, and the test should be conducted when the porcelain sleeve surface is dry to avoid interference.
**Base Insulation Resistance Test**
This test is performed before the annual thunderstorm season and when necessary. The insulation resistance is self-regulated based on the equipment's condition. A megger rated at 2500V or higher should be used for the test.
**Discharge Counter Operation Check**
This test is conducted before the annual thunderstorm season and when necessary. The discharge counter should be tested 3–5 times to ensure it operates correctly. After testing, the counter should be reset to "0".
These tests help ensure that metal oxide surge arresters are functioning properly and can protect electrical systems from overvoltage events. Regular maintenance and testing are essential to maintain system integrity and prevent failures.
Surge arrester is also called over-votage protector and over-volage lmiter. t is connected im paralle to the front end of the protected couipmen,. Whichprolects other clectrical equipment from lightning over-voltage, operating over-voltage, and power frequency transient over-voltage impac.
Composite Arrester,Electrical Insulation Composites,Electrical Box Insulation Covers,Composite Line Post Insulator
Jilin Nengxing Electrical Equipment Co. Ltd. , https://www.nengxingelectric.com