The Application of the Compensated Current Comparator to the Calibration of Current Transformers at Ratios Less than Unity

A technique is described for extending the range of the compensated current comparator so that it may be used for calibrating current transformers at ratios both greater and less than 1/1. The concept of providing compensation windings for both the primary and secondary ratio windings is introduced and a new method of correcting for the capacitance error due to burden is presented. Details on how a compensated current comparator previously developed for ratios from 1/1 to 240/1 may be adapted for this purpose are discussed and results of measurements at ratios down to 0.01/1 with this comparator are given.