Current transformer calibration

The practical application of the current comparator to current transformer calibration is accomplished with a configuration that has been called the compensated current comparator. The principal feature of this configuration is a winding located inside the main magnetic shield which has the same number of turns as one of the ratio windings located outside this shield. By connecting these two windings in parallel it is possible to operate the two ratio windings and the magnetic shield as a normal current transformer, thus enabling energy transfer between the primary and secondary circuits, without altering the over all ampere-turn balance imposed on the magnetic core.