GB831888A - Improvements in and relating to electrohydraulic apparatus for controlling hydraulicactuators more especially for operating section switches - Google Patents

Abstract

831,888. Controllers. GRATZMULLER, J. L. April 17, 1957 [April 18, 1956], No. 12509/57. Class 38 (3). [Also in Group XXIX] The movable contact mechanism of a section switch is closed and opened by a double-acting hydraulic jack or by single-acting jacks which are respectively controlled by valves 1, 2. A push-button 20 is pressed to close the section switch, so energizing coil 10 and depressing armature 9, whereby holding-contacts 11 are closed. Contacts 12 open the circuit of coil 16, and contacts 13 establish a circuit for coil 32 so that motor 4 is started to drive pump 3, and contacts 33 are closed to complete the holding- circuit of coil 10. At the same time, armature 9 depresses the plunger of valve 1 and interconnects pipes a and c to energize the appropriate actuator. When the actuator completes its stroke, the consequent rise of pressure in pipe 35, which is subjected to the delivery pressure of pump 3, opens switch 39 to deenergize coil 32, stop the motor and pump, and open the holding-circuit of the coil 10. The switch 39 is biased to the closed position by means of a calibrated spring 40. The section switch may now be opened by depressing pushbutton 21 to energize coil 16, the subsequent cycle of operations being similar to that described. When the system is in its inert state, the coils 10, 16 are doubly isolated by doublepole contacts 24, 25, and 26, 27, as well as by contacts 11, 17 and 33. The motor cannot be re-started immediately after a supply-failure since de-energization of coil 32, which is fed from two phases of the three-phase supply, opens contact 33 so, in turn, opening that contact 13 or 19 which was closed at the time.