Rapid Measurement of Leakage Current in Zinc Oxide Surge Arresters: Application Case

According to the electric power industry standard "DL/474.5-2018 Field Insulation Test Implementation Guidelines - Surge Arrester Test" section 9.1, for detecting moisture ingress or deterioration of metal oxide resistor discs inside surge arresters during operation, the method of regularly testing the operating frequency continuous current can be adopted. Normally, the continuous current through a surge arrester is very small. Once moisture ingress occurs, the current can increase to several milliamps or even tens of milliamps. Since the operating voltage often fluctuates, it's challenging to establish an absolute standard for determining severe moisture ingress. However, past records and comparisons among the three phases can be made. If there's a significant difference in leakage current, action must be taken.

Today, we introduce a simple testing method that does not require power cut-off or disassembly of the surge arrester to quickly test the leakage current of zinc oxide surge arresters. Developed by Guangdong ETCR Electronic Technology CO.,Ltd., the ETCR9400 Clamp Zinc Oxide Surge Arrester Live Tester consists of a main unit, detector, and insulating rod. The main unit and detector communicate wirelessly, allowing the main unit to remotely control the opening or closing of the detector's clamp to complete the testing process, with real-time display of current test values and clamp status on the main unit. The detector uses a micro-motor to drive the opening or closing of the clamp, and can be connected to an insulating rod for testing high-voltage overhead lines.

For testing, there's no need to cut power or climb heights. Install the detector on an insulating rod and clamp it around the zinc oxide surge arrester's grounding wire to detect the arrester's leakage current. Based on the leakage current tested by the instrument, personnel can decide whether the arrester needs maintenance, avoiding blind disassembly and saving a significant amount of labor.

Operational Steps:

1.Check whether the battery of the main unit and detector is sufficiently charged, requiring charging if below 50%.
2.Ensure an emergency pull ring is installed for use in emergencies.
3.Install the detector at the insulating rod interface, which allows adjustment of the detector's clamp direction for easy clamping of the conductor.
4.Press the “OPEN” button to open the detector's clamp.
5.Raise the insulating rod to clamp the conductor. After confirming the conductor is clamped, press the “CLOSE” button to close the clamp, entering the testing state.
6.After reading the test value, press the “OPEN” button to open the clamp and remove the detector from the conductor. After lowering the insulating rod, press the “CLOSE” button to close the clamp and remove the detector from the insulating rod, then retract the insulating rod.

Features of the ETCR9400 Clamp Zinc Oxide Surge Arrester Live Tester include: