| 摘要 |
PURPOSE:To inhibit action when any of three-phase AC phases is omitted, by providing the first, second, and third current relays and the fourth current relay that drives the first one by cooperation with the second one. CONSTITUTION:When switches 6, 6' are closed by impressed voltage on three- phase input cables 1', 1'', 1''', then a rectifier 5 outputs direct current, which is impressed on a sequence circuit. On the other hand, when a current relay 12 is driven by three-phase AC input, its contact 12' closes, and a current relay 7 sets in action on the output voltage of the rectifier 5; at the same time, an indicator 9 is lighted. Further, when a switch 10 is closed, a current relay 8 is driven because a switch 11 is normally closed and the contact 7' of the relay 7 is closed, and its contact 8' closes; therefore, the relay 8 is self-held even on the opening of the switch 10. Besides, the contact 8'' of the relay 12 also closes, and a current relay 3 is driven on a current relay power source 4 because of the closure of the contact 12'' of the relay 12; then, contacts 3', 3'', 3''' close. |
