FAULT CURRENT TRIPPING DEVICE SENSITIVE TO PULSATING CURRENTS

摘要

The invention concerns a current transformer (1) which comprises essentially a torus (2) with a magnetic core, primary windings formed by the active conductors of an electrical installation to be protected, and a secondary winding (3) at whose terminals a differential fault signal is produced when a differential fault occurs in the primary windings. The transformer (1) is characterized in that the magnetic core of the torus has a ratio between the dynamic induction increase at 400 Hz and the dynamic induction increase at 50 Hz of more than 0.7 for a field intensity amplitude of approximately 35 mAt/cm. The tripping device (D) comprises a transformer (1) of the above type, a tripping relay (4) and a secondary circuit (5) connecting the relay (4) to the transformer (1). The secondary circuit (5) has a capacitor connected in series with the secondary winding (3) or a full wave rectifier (6, 7).