| 摘要 |
PROBLEM TO BE SOLVED: To detect DC ground fault surely even when an offset is present due to temperature drift, or the like, or in the case of high resistance grounding or low resistance grounding. SOLUTION: The DC ground fault detector is connected with a power converter 2 for converting DC power from a DC power supply 1 into AC power being linked with a grounded neutral single phase three-wire power system 36 and detects DC ground fault where a ground fault flows from the DC power supply 1 through the neutral of the power system 36. Difference between currents flowing, respectively, through the positive and negative electrodes of the DC power supply 1 is taken in as a common current and DC ground fault is detected based on the common current. DC ground fault 15 detected by extracting from the common current a signal having frequency component equal to two times of the power supply frequency of the power system 36. A detection level setter 45, a comparator 44, or the like, are additionally provided. |
