| 摘要 |
PROBLEM TO BE SOLVED: To surely discontinue power supply to a load even when the control of an SSR(solid-state relay) with a control signal becomes impossible. SOLUTION: A switch circuit 72 is connected between a power source 78 and a feed pump 56. To the circuit 72, an SSR 80 and a timer 86 in which contacts 82 and 84 and a timer coil 86A are integrally provided are connected. The contact 82 is normally closed and the contact 84 is normally opened, but, when the timer coil 96A is actuated after a prescribed period of time, the contact 82 is opened and the contact 84 is closed. Therefore, the power supply to the pump 56 connected to the contact 82 is forcibly discontinued. On the other hand, a photocoupler 88 connected to the contact 84 makes a continuity and outputs an signal indicating the occurrence of abnormality to a water supply control section. |
