On-line partial discharge measurements on power transformers require the installation of coupling devices using the capacitive tap of the transformer bushings. The bushing couplers offer wide-band partial discharge signals as well as wide-band voltage measurements to analyse the transfer impedance. The ICM system equipped with the 8-channel input multiplexer and operated with the ICM mux software allows semi parallel measurements on up to eight channels to study discharge activity and cross-coupling over the windings.
