In the condition monitoring device of the self arc extinction die

摘要

PROBLEM TO BE SOLVED: To monitor the state of a switching element accurately even when an inverter is stopping while being linked with a power system.;SOLUTION: A failure detection circuit 10 conventionally monitors the state of a self-extinguishing element 1' in a self-excited inverter 2 by logically judging the output from a pulse generating circuit 6 generating an on/off command, and the output from a circuit 7 for monitoring the terminal voltage of the element 1'. Since a normal element 1' may be judged erroneously as a failed element when an inverter is stopping while being linked with a power system, a counter 16 for detecting the output from the failure detection circuit 10 is provided and a decision is made that the element 1' has failed only when the failure state thereof sustains for a predetermined time or longer thus avoiding erroneous judgment.;COPYRIGHT: (C)2003,JPO