Circuit arrangement for monitoring and detecting the failure of the neutral conductor or a phase conductor of a three-phase network

摘要

The circuit produces a signal when a failure is detected. The phase lines (L1-L3) are connected via resistances (R1-R3) to a star point (3) which is connected via a load (V1,R5) to the neutral conductor (N). The voltage supply to the circuit is obtained via two phase conductors (L2,L3). A measurement circuit (R4,V3,R9) measuring the current flowing between the third phase conductor and the neutral conductor is connected to a comparison circuit (N1B,N1C) which compares the signal from the measurement circuit with a predefined threshold voltage and may generate the failure signal depending on the result of the comparison.