Measurement uncertainty in on-line bushing monitoring

The high voltage bushing on-line monitoring has been performed for many years to prevent unexpected rapid power network failures. Network unbalance correction, based on separate voltage phase measurement or phasor technique, effectively improves the measurements of bushing dielectric dissipation factor tgδ and capacitance factor C1. The newly implemented monitoring units reveal that the uncertainty of station voltage measuring transformers manifest the greatest influence on the overall uncertainty budget, regardless of the measurement method.