| 摘要 |
PURPOSE:To detect the abnormality of an output voltage irrespective of the mean value of a line voltage. CONSTITUTION:The peak value of an output voltage at every phase from an output-voltage-detection transformer 3 for an uninterruptible power supply apparatus (OPS) is compared, by a comparator 14, with a peak-voltage set value which has been set at a setter 13 for every half cycle, and its voltage- abnormality detection pulses are output to a counter 16, and the counter 16 counts the pulses. When its counted number reaches the set count number of 40 by a setter 18, it is judged that a detected abnormality is caused not by a disturbance but by the abnormality of the UPS. The number is output to a memory circuit 19, the OPS is stopped as a serious fault via the memory circuit, and the abnormality processing of a bypass changeover is output. |
