| 摘要 |
PURPOSE:To prevent the leakage of fuel, such as raw gas under unprocessed state from a burner in a subjected circuit for a hot water supply device and the like, by monitoring the state of a power switch for a solenoid valve, forcedly halt the operation of a fan motor during emergency, and separating said power switch for the solenoid valve. CONSTITUTION:When a fan motor drive signal (2) is output, a relay contact is closed, than a fan motor 11 is rotated, when a gas solenoid relay 14 is on, the output potential of a photo coupler is forcedly turned in a L level, thereby turning off a diode 17. On the other hand, a solenoid valve open signal (1) is not given yet so that the diode may not be opened yet. Therefore, the both- end voltage 10 of a capacitor 21 is discharged by way of resistors 19 and 20 and lowered, which reversed a NAND gate to H, de-energizing a relay RM for fan motor dive, then compulsorily halting the operation of the fan motor 11. It is, therefore, possible to upgrade the safety of burner due to this construction. |
