Electrical lifespan prediction of high-voltage direct-current relay based on arc charge accumulation

Abstract

Electrical lifespan prediction has always been one of the greatest challenges in switching apparatus. In this paper, a mathematical model based on arc charge accumulation from experiments is set up to predict the electrical lifespan of high-voltage direct-current (HVDC) relays. The electrical circuit condition is 270VDC/200A, resistive load. The contact pair is bridge-type and made of copper. Experiments are carried out with a parameter-adjustable device in similar with actual HVDC relay structure. The magnetic field flux density for arc blowing is controlled in the range of 40mT to 80mT. The arc current waveforms are acquired and the arc charge during each breaking operation is calculated. The arc charge is accumulated until it reaches threshold value, which is decided according to electrical lifespan test results of actual products. The relationship between the lifespan and the magnetic field flux density is constructed, which can be used for lifespan prediction.