Automatic system for monitoring leakage current on valve surge arrester

Abstract

A valve surge arrester is a device commonly used in substations to protect power grids and electrical equipment from the effects of lightning. The quality of the valve surge arrester is evaluated by measuring and analysing the leakage current of the surge arrester. The magnitude of the resistive component in the leakage current is considered proportional to the degree of degradation of the ZnO block, or dirty’s surface of the valve surge arrester. Equipment that does not meet the requirements must have its surface cleaned or replaced to ensure safety and avoid loss to the power grid. This article proposes an online monitoring and warning solution for surge arrester devices based on digitising analogue signals, communicating, analysing, and storing the value of the leakage current of the surge arrester device. This solution got a maximum relative error of 3% when tested in the measurement range from 0÷30 mA. Low power long-range (LoRa) communication and 4G networks allow the leakage current value to be monitored remotely, meeting the needs of early warning and support for the operation of transformer stations, especially at unmanned substations.