OPERATION CHECKER FOR EARTH LEAKAGE BREAKER WITH OPEN-PHASE PROTECTIVE FUNCTION FOR SINGLE PHASE AND THREE-PHASE

摘要

PURPOSE:To provide an operation checker for open-phase protection ELB in which the open-phase protective function can be checked easily at site. CONSTITUTION:Power supply terminals 3, 4 are connected through a power supply switch 6, a fuse 7, and a current limit resistor 8 with the fixed terminals 9a, 9b of a variable resistor 9 whereas a detection terminal 2 is connected through a detection switch 5 with the sliding terminal 9c of the variable resistor 9. The power supply terminals 3, 4 are also connected with the load side voltage line terminals 54, 56 of an ELB 50 and the detection terminal 2 is connected with the overvoltage detection lead wire 69 removed from the load side neutral. When the dial of the variable resistor 9 is turned from an intermediate position, the voltage between any one of terminals 54, 56 and the lead wire 69 increases and the ELB 50 is opened when a predetermined voltage is exceeded.