| 摘要 |
PURPOSE:To rapidly improve a short-circuit protection capacity by making a back- up movement irrelevant to machining voltage possible by providing a back-up circuit to a short-circuit protection device of an electro-chemical machine. CONSTITUTION:Current from a power source terminal 1 flows between an electrode 5 and a work 6 through an air circuit breaker 2, an A contact 3a of a main circuit relay 3, and a commutating circuit 4, and voltage between the electrode 5 and the work 6 is input to a short-circuit protection relay circuit 7 of which output current flows to a pull-out coil 9 of the breaker 2 through an A contact 10 of a auxiliary relay during machining. Also, a B contact 26a of a relay 26 of a short-circuit protection back-up relay circuit 29 is connected to the relay 3 in series. Then, the A contact 3a is opened by optically-detecting discharge generated by a short-circuit accident between the electrode 5 and the work 6 in a machining tank 30 of the electro-chemical machining, and a machining current circuit trips and a short- circuit protection back-up motion of the machine is completed, so that the short- circuit protection capacity can be rapidly improved. |
