PURPOSE: To eliminate the complexity of selecting an a.c. machine and set a given level of tester current by making a wiring breaker and a current transformer into an integral structure and drawing out secondary output terminals of the current transformer into outside the casing.
CONSTITUTION: Zero phase a.c. machine connection terminals of a leak relay 5 are respectively connected to terminals k and of a wiring breaker 1 containing a zero phase a.c. machine 2 and a tester circuit 6 connected thereto in series with a resistor 8, a push button 7 and a power source 9 is respectively connected to tester terminals kt, t of the machine 2. In the circuit 6, depression of a push button causes a predetermined level of current set beforehand by the resistance value of the resistor 8 and the power source 9 to flow in a tertiary winding of a current transformer 2. Thus, the leak relay operates. Further, since the tester circuit can be separately arbitrarily provided, it is possible to set a given level of tester current.
KIRYU TOMIYOSHI
SUZUKI YUKIO
HIRASAWA KIYOMICHI
HITACHI TECHNO ENG
HITACHI ELECTRIC SYSTEMS