| 摘要 |
PURPOSE: To prevent generation of trip failure and to rapidly detect and display disconnection and insulation defect by providing a detection means for detecting insulation defect and disconnection of a switch based on a combination pattern of opening/closing state of a first contact and a second contact. CONSTITUTION: An electric contact 34 is usually connected to a contact Nc. An exciting coil Y is excited and a contact 35 thereof is turned off and an exciting coil X is not excited. An exciting coil Z is not excited either. If trouble occurs, the exciting coil Y is not excited since the electric contact 34 is connected to a contact No and the contact 35 of the exciting coil Y is turned on, and the exciting coil X and the exciting coil Z are excited since the contact 35 of the exciting coil Y is turned on. Furthermore, a contact 37 of the exciting coil X is turned on and a trap signal is output. Meanwhile, a contact 39 of the exciting coil X is also turned on, the exciting coil 30X is excited, a contact 41 thereof is turned on and an operation display signal is output. |
