PROTECTIVE DEVICE HAVING A CIRCUIT BREAKER, IN PARTICULAR A LOW-VOLTAGE CIRCUIT BREAKER

摘要

The invention relates to a protective device (2) having a circuit breaker (3) for an electrical connection between a transformer (1) and a load (V), wherein an overcurrent device is arranged between the transformer (1) and the load (V), which overcurrent device has first magnetoelectric transducers (4) arranged at each phase conductor (Ll, L2, L3) and the neutral conductor (N), wherein the overcurrent device uses the transducer currents to in each case establish the presence of a first ground-fault current, and wherein the circuit breaker (3) has a switching device, which interrupts at least the phase conductors (Ll, L2, L3) between the transformer (1) and the load (V) in the event of the presence of a first ground-fault current (unrestricted earth fault). In order to also be able to determine the ground-fault current between the transformer (1) and the circuit breaker (3), the invention proposes providing in each case second magnetoelectric transducers (8) at each phase conductor (Ll, L2, L3), the neutral conductor (N) and a star-point conductor (9) which is connected to the star point, using the transducer currents of the second transducer (8) in each case to determine the presence of a second ground-fault current (restricted earth fault), and forming a signal for disconnecting the transformer (1) in the event of the presence of a second ground-fault current.