Overvoltages in secondary circuits of air-insulated substation due to disconnector switching

Abstract

Investigations of the electromagnetic interference indicate that disconnecting switching of the off-loaded busbars is one of the most important sources of electromagnetic interference in the secondary circuits of a power station. Disconnector's contacts in air-insulated substations (AIS) move slowly causing numerous strikes and restrikes between contacts. Every strike causes high-frequency currents (from a few hundred kHz to a few MHz) tending to equalize potentials at the contacts. These travelling current and voltage waves are the most important sources of electromagnetic coupling to the secondary circuits of instrument transformers, on whose ends high-speed and lowpower electronic devices are connected. During disconnector switching malfunctioning of auxiliary circuits can occurred. In this paper results of measurements of overvoltages in the secondary circuits in the AIS Grabovica (Hydro Power Plant -HPP Grabovica) and AIS Kakanj are presented. In order to reduce overvoltages in secondary circuits, measures for mitigation of electromagnetic interference are presented.Index Terms-Switching, overvoltages, air insulated substation (AIS), disconnector, electromagnetic interference (EMI), disconnecting circuit breaker (DCB), secondary circuits.

Mechanical defect detection of porcelain column high-voltage disconnector based on operating torque

“…1,2 Most porcelain column high-voltage disconnectors work directly in the outdoor environment, thus are subject to the erosion of wind, frost, rain, and snow. Besides, a few attention has been paid to the daily maintenance and repair due to their relatively simple structure and low cost, resulting in frequent faults and defects, 3,4 such as mechanical defects, 5 conductive loop overheating, 6 secondary circuit defects, 7 and insulator damage defect. 8 Among them, mechanical faults and defects are particularly severe.…”