RELAY UNIT, CONTROL METHOD OF RELAY UNIT

摘要

The purpose of the present invention is to improve the reliability of a relay unit for monitoring a normally close contact point. The relay unit transmits first diagnostic signals to the first normally close contact point when an electric current is not applied, detects a return of the transmitted first diagnostic signals, transmits second diagnostic signals different from the first diagnostic signals to a second normally close contact point, detects a return of the transmitted second diagnostic signals. At least one between a case in which a result of detecting the return of the first diagnostic signals does not meet a first preset condition and a case in which a result of detecting the return of the second diagnostic signals does not meet a second preset condition is determined as a malfunction of the relay unit. The relay unit includes: first and second normally open contact points; the first and second normally close contact points; a conversion circuit; and a control unit.