On-line calibration of high voltage current transformers

Calibration of current transformers, used in high voltage networks, is difficult to perform because conventional methods need to disconnect the transformer from the network, interrupting the electricity service for many hours. This is inconvenient and has high costs. In this paper, an alternative calibration method is proposed which does not need to interrupt the service. All measurements are done using the service current as excitation. No intervention is required on the high voltage transformer side. This proposal is also useful for current transformers used inside power transformers and generators, where it is very difficult to access to the primary circuit.