| 摘要 |
<p>PROBLEM TO BE SOLVED: To protect a generator, by detecting a negative-phase current against a fundamental wave or a harmonic current and preventing abnormal heating in the generator. SOLUTION: A current in a generator (G) is detected by a current transformer(CT) and separated into a fundamental wave current and a harmonic current in a wave analysis circuit 21 to calculate an equivalent negative phase current in a wave form calculation circuit 22. Then, a comparing circuit 23 judges abnormality if the equivalent negative-phase current is above a limit value set in a setting circuit 24. When the abnormality is judged, a trip command (T) is generated to make a breaker (CB) open.</p> |
