| 摘要 |
PROBLEM TO BE SOLVED: To interrupt the feeding of an AC power to the primary winding of a transformer, when its case is not in contact with the ground. SOLUTION: When inputting an AC power supply 13, operating a relay 22c, its contacts 22a, 22b are turned on. At this time, when a grounding terminal 18 is in contact with the ground, making flow a current in a light emitting element 26 and turning on a light receiving element 39, the output of a comparator 42 turns into high level and a diode 45 is reverse biased, to disable a light emitting element 46 and connect an AC power with a primary winding 12 owing to the intact off-state of a triac 48. Meanwhile, when the grounding terminal 18 is not in contact with the ground, disabling the light emitting element 26 and making the output of the comparator 42 a low level, the light emitting element 46 is enabled, and the triac 48 is turned on to turn off a connection point 49a through the operation of a relay 49c and interrupts the feeding of the AC power to the primary winding 12. |
