On the Mechanical Short-Time Rating of a Current Transformer

Closed form expressions and a finite-element method are used to compute the maximum force in the primary conductor of a wound current transformer (CT). It is shown that for a given volume for the primary winding, one configuration exists that leads to a maximum force. It is proved that the mechanical short-time rating of two CTs having different turns but identical ampere turns is not equivalent. Designers can now establish and test a CT with a worst-case configuration.