| 摘要 |
<p>PURPOSE:To enable highly reliable detection, by turning OFF a series circuit composed of a switch and a signal output section when a switch is closed or opened to eliminate abnormal operation due to arc generated during the closing or opening operation of the switch. CONSTITUTION:Light generated by a ground fault is transmitted to a processing section 11 through a detecting section 9 and an optical fiber 10 to turn ON a signal detecting section 11D. On the other hand, as limit switches 14 or 15 at a locking section 12 is OFF, a series circuit of the switch 15 is turned OFF and hence, an auxiliary relay 16 fails to be excited with a normally closed contact 17 kept closed. As a result, a series circuit of the normally closed contact 17 at the locking section 12 and the signal output section 11D at the processing section 11 is closed to operate a signal receiving section 13A of a display device 13 and abnormality is shown on a display device 13B. Even when arc is generated during the opening or closing of the switch, the output section 11D is turned ON. On the other hand, with the limit switches 14 and 15 ON, the normally closed contact 17 is opened and thus, no abnormality display is given.</p> |
