The lift-off effect analysis of flexible differential pick-up koch fractal eddy current probe

This study utilized finite element simulation and experimental methods to investigate the evolution of crack detection performanceof a flexible differential fractal Koch eddy current probe at different excitation frequencies as the lift-off distance increases.As the lift-off distanceincreased,the distribution shape of induced eddy currents changed,leading to reduced similarity in the shape of the excitation coil and an expandeddistribution range of induced eddy currents,ultimately resulting in weakened output signal strength.The experimental results showed that forexcitation frequencies of 10 kHz,20 kHz,50 kHz,100 kHz,200 kHz,500 kHz,and1000 kHz,the maximum lift distances of the real partof the output signal when cracks were detected were 5.0 mm,7.0 mm,8.0 mm,8.0 mm,8.0 mm,6.5 mm,and 4.0 mm,respectively.Theimaginary parts were 6.5 mm,6.5 mm,7.5 mm,5.5 mm,8.0 mm,6.5 mm,and 6.5 mm,respectively.

一起10 kV Ⅱ段母线失压故障分析

雷雨天气造成变电站10 kV Ⅱ段TV三相一次保熔断,满足10 kV备自投装置检无压条件,由于10 kV Ⅱ母所带负载过小,且在10 kV 59019线跳闸且重合之后,部分负荷暂时未能启动恢复,导致Ⅱ母A相二次电流为减小至0.06 A,满足10 kV备自投Ⅱ母检无流的条件,10 kV备自投启动,延时跳开5902开关,由于备自投合母联开关硬压板未在合闸投用状态,造成合母联开关失败,10 kV Ⅱ母电源未能得到恢复。