| 摘要 |
PURPOSE:To enhance the safety during operation very much and to ensure the safety against leak or other emergencies by insulating and separating electrically the water level detecting circuit side from a main electric circuit to operate it when the water level detecting circuit side is set to the detectable state. CONSTITUTION:AC power is dropped by an insulating transformer 14 and is converted to DC by a DC power source circuit 15, and the DC power is supplied to a main circuit part 30. In this state, a relay 16 is turned off, and a relay contact 17 is switched to the B (break) contact side, and a prescribed DC voltage is charged in a large-capacity capacitor 18. When a set button switch is depressed, a switching circuit 19 is operated to turn on the relay 16, and the relay contact 17 is switched to the M (make) contact side. In this state, a water level detecting circuit 20 uses the capacitor 18 as the power source to start operating. As a result, the power is supplied to the device by the power source capacitor 18 of the water level detecting circuit 20; and thus, the safety during operation is very high, and the device is made strong against static electricity and external noise such as an impulse noise. |
