| 摘要 |
PURPOSE:To stabilize-the operation of a network relay device and reduce the cost. CONSTITUTION:A reverse power detecting element is composed of a small current reverse power detecting element, which detects reverse power based on the phase difference between the voltage of a network and the current at a specified value or less, a large current reverse power detecting element 2, which detects the reverse power based on the phase difference between the voltage and the current at a specified value or less, a timer 3, which reserves the output of the detection signal from the small current reverse power detecting element 1 for a certain time, and an OR circuit, which takes the OR condition between the output of the timer and the output of the large current reverse power detecting element 2. And it is so arranged as to suppress the unnecessary operation of a breaker driving element 21, which drives a protector breaker, on one side and operate the breaker driving element 21 on the other when the reverse power by a large current has occurred. |
