Calibration of an instrument current transformer at a ratio of 20 kA/5 A

This paper presents two methods for determining the ratio error and phase displacement of an instrument current transformer (ICT) with transformation ratio 20 kA/5 A. In the first case, the primary conductor passed by a current 20 kA placed in the centre of the toroid is replaced by a current loop with 10 turns placed in the centre of the toroid. In the second case, the conductor is replaced by 10 turns uniformly distributed along the circumference of the toroid. The primary current 2 kA is measured in both cases using a toroidal current comparator, and the secondary current difference is evaluated by means of an ICT error measurement system.