Transformer bushing failures are considered as one of the major causes of transformer outages. Historically, bushings were tested with off-line methods to measure the capacitance and dissipation/power factor.

The ZVCM-1001m is a permanently installed on-line bushing monitoring system. It continuously measures leakage currents from up to six bushings. With a double system, up to twelve bushings may be monitored. Power factor and capacitance values are calculated and various test method algorithms are applied. Free-standing CCVTs, circuit breaker bushings, and GIS-to-AIS transition bushings may all be monitored.