Device and method for the differential protection and electrical apparatus including such a device

摘要

The device has an energizing circuit to energize a magnetic circuit (4) of a differential current transformer (2) with an energizing signal (IE) at an excitation frequency (F1). A control circuit is provided for controlling and changing the exciting frequency and for providing the signal (IE) of the magnetic circuit with an exciting frequency (F2). The frequency (F2) is different from the exciting frequency (F1). Independent claims are also included for the following: (A) an electrical apparatus including a differential protection device (B) a process of differential protection.