| 摘要 |
PROBLEM TO BE SOLVED: To provide an earth fault detecting circuit detecting not only the occurrence of earth fault and its place but also whether DC voltage is applied on a load or not simultaneously. SOLUTION: This earth fault detecting circuit 20 for detecting earth fault in a positive side feed line and a negative side feed line which connect a DC voltage source with a load, is provided with: a constant current element 23 and a photocoupler 22 connected mutually in series between the positive side feed line 32 and a grounding point 24; and a constant current element 27 and a photocoupler 26 connected mutually in series between the negative side feed line 34 and the grounding point 24. The constant current elements 23 and 27 are the elements maintaining the passing current at a constant value, and the photocouplers 22 and 26 are the elements detecting flow of the current having the constant value. COPYRIGHT: (C)2010,JPO&INPIT |
