| 摘要 |
PURPOSE:To obtain a circuit breaker, provided with an advance warning, where in, even when a detection voltage having a large value is applied to a base for a pair transistor, a large voltage drop is not caused in an emitter resistance by a method wherein the value of the emitter resistance for the pair transistor which makes an overcurrent tripping characteristic and an advance warning characteristic uniform is changed over to a low value according to the magni tude of a detection voltage corresponding to a main-circuit electric current. CONSTITUTION:This circuit breaker is provided with an effective-value conversion circuit 17 which detects a voltage corresponding to a main-circuit electric current and which outputs a detection voltage and with a pair transistor 18a4 which is turned on by the detection voltage detected by the effective-value conversion circuit 17 and which outputs a charging current. In addition, the circuit breaker is provided with FETs 18a13b, 18a13a by which resistors 18a61, 18a51 are connected, according to the value of the main-circuit electric current, in parallel with resistors 18a6, 18a5 inserted in emitters for individual transistors 18a2, 18a3 constituting the pair transistor 18a4. |
