Wide ratio current transformer with fixed primary turns

Abstract

The application provides a current transformer with fixed primary turns and wide variable ratio, which is composed of two current transformers CT1, CT2 and a switching switch K1. The current transformer comprises a primary coil, a secondary proportional winding, an error current detection winding, a compensation winding and an operational amplifier. The current transformer of the application adopts a three-stage iron core, an active compensation design, the primary winding N1 of the current transformer CT1 adopts fixed turns, the primary winding N1' of the current transformer CT2 adopts a variable turns design, and the error current is fed back to the compensation winding through the detection winding on the iron core, so that the problem of excessive input impedance of small current can be solved, the proportional error under small current can be greatly reduced, and the current measurement accuracy is effectively improved.

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