JPH0142388B

PURPOSE:To obtain an opportunity to repair an operation failure through scheduled power interruption, by monitoring the behavior of a switching equipment during daily operation and detecting the failure when the failure may cause a certain damage in future regardless of hindrance for daily operation. CONSTITUTION:When a tripping command current is given to a switching equipment in a closing state, since a contact 4 is closed, a coil 3 of the 1st time limit relay is excited, and no contact 4 is opened after preset time. A contact 5 continues the excitation of the 1st time limit relay when the tripping current duration time is especially short and it is not necessarily provided. When moving contacts of the main electrodes move and reach a position a2, a contact 6 is closed and contacts 7 and 8 are kept opened, then the 2nd timer 9 is excited. This excitation is kept until the moving electrodes reach a position a3 and the contact 7 is opened. If this excitation continuing time is longer than a preset delay time, the 2nd time limit relay 9 is to issue alarms.