| 摘要 |
PURPOSE:To prevent accident of explosion or the like resulting from erroneous wiring connection of grounding phase of the power supply circuit to a control box by a method wherein power can be supplied to a control circuit only when polarity of both the power supply and control circuits is matched. CONSTITUTION:A relay X to confirm abnormality is provided between an earth line 3 and a grounding point E in the subject circuit located between the hot line 2 and earth line 3 in which a combustion solenoid valve SV, an ignition transformer IGT and the control circuit 1 for the above are provided. A pair of a-contact Xa of the relay X and an abnormality indicator lamp RL are provided between both the lines 2, 3. In addition, a pair of b-contact Xb of the relay X is provided on the earth line 3 at a point beyond the abnormality indicator lamp RL but no farther than the control circuit 1. This feature allows application of voltage on the relay X to open the pair of contacts Xb when grounding phase of the power supply circuit is erroneously applied to the R- phase, thereby power supply to the control circuit 1 can be impeded. Simultaneuosly, the abnormality indicator lamp RL is lighted to inform erromeous wiring by closing the pair of contacts Xa. |
