High Voltage Current Transformer Arcs, Requiring Generator Activation

Location: Prince George
Regulated industry sector: Electrical - Low voltage electrical system (30V to 750V)

Incident Overview

Three high voltage current transformers (CT) monitor how much electricity flows through the high voltage switchgear. One of the high voltage CTs arced to the switchgear enclosure. The failure caused the BC Hydro fuses to trip, which caused the emergency generator to start. A second generator large enough to run the whole building was brought in until the high voltage switchgear could be repaired. The CT was cracked in the molded case around the CT, exposing the internal high voltage winding. Where the CTs are installed is unheated and moisture buildup in the porous insulating material and winter freezing temperatures may hay contributed to the insulation cracking. The winding arced across the air gap to the grounded high-voltage metal switch gear enclosure.