By hvhipot 
Lightning arrester is one of the important electrical equipment in the power system, which plays a crucial role in the safe operation of the power system. Zinc oxide lightning arrester (MOA) is a new type of lightning arrester that differs greatly from other types of lightning arresters. Due to its obvious performance advantages, it has been widely promoted and applied in power systems.
In order to ensure the safe and reliable operation of zinc oxide lightning arresters in the power system, the main contents of the preventive testing regulations for zinc oxide lightning arresters in the power industry standard DL/T596-1996 “Preventive Testing Regulations for Power Equipment” are as follows:
(1) During the DC leakage current test, the voltage U1mA at 1mA should not change by more than ± 5% compared to the initial value or the manufacturer’s specified value. The leakage current at 0.75U1mA voltage should not exceed 50 μ A.
(2) When the measured values of full current, resistive current, or power loss under operating voltage show significant changes compared to the initial values, monitoring should be strengthened. When the resistive current increases by a factor of 1, power outage detection should be carried out.
According to the regulations, the preventive test of zinc oxide lightning arrester includes DC leakage current test under power outage conditions and live test under operating voltage. However, when the operating voltage of the power system is high and there are many lightning arresters in the power plant (or substation), it is very difficult to conduct DC leakage current tests under power outage conditions. Therefore, on-site live testing of zinc oxide lightning arresters under operating voltage is becoming increasingly important.
Oxidative surge arresters were promoted and applied in the mid-1980s. In 1996, the “Regulations” issued by the state had clear provisions for on-site live testing of oxidative surge arresters under operating voltage. With the rapid development of computer technology and the continuous improvement of the testing level of high-voltage electrical equipment, it has been proven in practice that testing more items of oxidative lightning arresters (such as the effective values of resistive current and capacitive current leakage current, peak values of resistive current and capacitive current components, harmonic components of leakage current, power loss values of harmonic components, etc.) can more accurately reflect the operating status of lightning arresters. The following table shows a set of data obtained from on-site testing of zinc oxide lightning arresters produced by HV Hipot Electric Co., Ltd. Company during operation at a 330kV substation.
After analyzing the data in the table, it was found that the resistive current Ir of the on-site C-phase lightning arrester increased rapidly after exceeding 0.3mA (peak), which was 20 times that of the initial operation. Therefore, it was decided to shut down the lightning arrester. After disassembly and inspection, it was found that the internal components of the lightning arrester were not qualified and had been dampened.
If users follow the regulations to conduct DC leakage current tests under power outage conditions before the thunderstorm season each year, defects in the C-phase lightning arrester may not be detected in a timely manner, and the consequences could be unimaginable. Therefore, on-site live testing of oxidative lightning arresters under operating voltage is of great significance!