On the 5th August, a sharp increase of Partial Discharge activity was detected on a 33kV switchgear panel by IPEC’s online PD Monitoring system, the ASM. High TEV PD signals were detected across the switchboard.
On 9th August 2016, an on site investigation to locate the defect followed by switching operations. The PD source was identified as originating from the VT chamber of an important feeder which supplies to another substation.
The VT and circuit breaker were de-energised and CB racked out. Upon switching out the panel, the PD activity stopped. A visual inspection was conducted on the VT and evidence of carbon tracking and oil was visible on the spout connector. A leak was identified on the yellow phase of VT.
IPEC identified and located a source of PD on a 33kV switchgear panel. A combination of HFCT precedence testing, CC (TEV) precedence testing and airborne acoustic testing were used to locate the PD source. Following a remedial action, a switchgear fault was prevented.