| 摘要 |
PURPOSE:To prevent usage of product under dangerous state, by disabling operation of a product when the product is not grouded or the polarity of power source is reversed, and informing the cause thereof. CONSTITUTION:When a product is not grounded, input voltages Va, Vb to an abnormality monitoring circuit 9 are zero, and the abnormality monitoring circuit 9 outputs a source interruption command signal to turn a relay contact 11 OFF so as to disable operation of the product. At the same time, a relay contact 12 is turned ON to light an ineffective grounding display lamp 14. In case of reverse source polarity, the abnormality monitoring circuit 9 turns the relay contact 11 OFF so as to disable operation of the product, while turns a relay contact 13 ON to light an erroneous source polarity display lamp 15. |
