PURPOSE: To facilitate throw-in of power to a plurality of loads without requiring complex transmission circuit and receiving circuit by providing an arbitrary number of loads, to be connected with a DC power supply, with a power supply voltage variation detecting circuit and a power supply throw-in contact.
CONSTITUTION: When a power supply throw-in relay circuit 2 makes and breaks a power supply throw-in contact 3 a plurality of times, variation of power supply voltage appears at the output of a differentiating circuit 7 in a power supply voltage variation detecting circuit 4. The voltage variation is fed through a diode 8 and only positive voltage is fed to 8 circuit 9 for integrating the voltage variation. Thus integrated voltage is then compared through a comparator 10 with a reference voltage fed from a variable resistor 11 and if the integrated voltage is higher than the reference voltage, a relay 12 functions to feed power to a load 5. When the power throw-in relay circuit 2 does not switch the power throw-in contact 3 a plurality of times but simply throws in power, integrated value of voltage variation is low and the relay does not function thus feeding no power to the load 5.
YOSHIDA TOMIJI
OMOTE TATSUYUKI
HITACHI ENG CO LTD