SINGLE TIME LIMIT MEASURING CIRCUIT SYSTEM OF REGULARLY CLOSED CURRENT TRANSFORMER SECONDARY CURRENT TRIPPING TYPE EXCESS CURRENT RELAY

摘要

PURPOSE:To enable the measurement of the single time limit of an excess current relay without breaking a circuit breaker by connecting the primary winding of a current transformer to the terminal of the contact point of the excess current relay, and its secondary winding to the neutral polarity terminal of a power source switch through a series resistor. CONSTITUTION:The terminals 12, 13 of the B contact point 6 of an excess current relay 5 are connected to a power source switch 2 by a current transformer 9 and an electron element. A test current I is divided into IB, IT, IC, but the trip coil current IT is hardly sent, so that the circuit breaker is not broken. When the main contact point of the excess current relay is closed, the contact point 6B is immediately closed to change the current to IB=0, I=IC, and IT does not break the circuit breaker. However, the secondary current of the current transformer 9 is reached to a fixed level or more to break the power source switch 2, cutting the power source of a relay tester 3, and the self-contained time counter is stopped to display the single time limit of the excess current relay 5. Hence, the time limit can be measured without breaking the circuit breaker.