| 摘要 |
PURPOSE:To simplify an abnormality diagonising part and to enable the reduction in a voltage required for a power source device, by a method wherein two voltage detecting parts are provided, and a voltage applied between switching contacts is caused to match the total sum of a main and an auxiliary power source. CONSTITUTION:If there is no abnormality on a transmission line 1 and a switching terminal 10 which, in turn, is in contact with a terminal 30, a positive voltage of a main power source 50 is applied to an input 31 of a voltage detecting part 3 from a positive pole via a switching transmission line 11, the switching terminal 10, and the contact terminal 30, and the voltage detecting part 3 detects the positive voltage. Then, the positive voltage of the main power source 50 is applied to the switching teminal 10 and a negative voltage of an auxiliary power source 51 is applied to the contact terminal 20 whereto the switchig terminal 10 is energized. The negative pole of the main power source 50 and the positive pole of the auxiliary power source 51 are connected together with a reference potential 52, and thereby the total voltage of the main power source 50 and auxiliary power source 51 is applied between the switching terminal 10 and contact terminal 20. |
