Analysis of A Cable Sheath Voltage Limiter Explosion Accident

This paper analyses an exploding cable sheath Voltage limiter accident and reveals the unstable intermediate state of the it during moisture exposure by simulating water ingress tests of the Voltage limiter as well as insulation resistance and lightning overvoltage tests at various levels of moisture exposure. It was found that deposits or adsorbed layers accumulate on the surface of the valve sheet of the cable sheath Voltage limiter, increasing the resistance of the electrode surface and leading to an increase in resistance. The cause of this explosion accident may have been the failure of the insulation tester used to detect water ingress during the pre-test experiments due to the low conductivity of the hydride of ZnO. As a result, moisture was present inside the protector. When an overcurrent occurs, the liquid water in the moisture rapidly vaporises into water vapour, resulting in a sharp expansion in volume, generating a high pressure that exceeds the withstand capacity of the shell, ultimately leading to a rupture or explosion of the shell.