| 摘要 |
PURPOSE:To equalize a prealarm start current and an overcurrent removal start current and start prealarm with the overcurrent removal start current by providing a prealarm operation means which operates a prealarm generating means based on the operation start signal of the overcurrent removal means in view of starting the prealarm operation with the overcurrent removal start current. CONSTITUTION:A PAL pickup reference voltage to be impressed to a PAL pickup comparator 21a by adjusting variable resistors 20c, 20d of a characteristic setting circuit 20 is set higher than an LTD pickup reference voltage to be impressed to an LTD pickup comparator 18b. As a result, a current flowing through the main circuit increases and when the corresponding detected voltage exceeds the reference voltage of the comparator 18b, an output of the comparator 18b changes to the L level from the H level. 7 Therefore, since a forward current flows into a diode D through a resistor 21R, a limited operation transistor 21b turns off and a prealarm signal is generated from a comparator 21g. Simultaneously, a transistor 18c also turns off and a trip signal is generated from the comparator 18h. |
