GB803380A - Improvements in or relating to interlocked electric control circuits - Google Patents

Abstract

803,380. Switching systems. IGRANIC ELECTRIC CO., Ltd. May 3, 1955 [May 13, 1954], No. 12785/55. Class 38 (4). A switching system, for controlling the energization of a solenoid 18 operating an air valve V for a clutch 16 through which a press 14 is driven by a motor 12, comprises saturable reactors 20, 22, an initiating switch 24 and limit switches 28, 30 operated by the press. Reactor 22 has A.C. windings 46, 48, bias winding 52 and control winding 50, whilst reactor 20 has A.C. windings 36, 38 in series with the solenoid, bias winding 44 and control windings 40, 42. Assuming limit switch 30 and the auxiliary contacts 34 of the motor line switch 10 both to be closed and the initiating switch 24 to be in the normal position shown, the rectifier system 57- 60 (which supplies the bias windings 52, 44) also energizes control winding 50, thereby saturating reactor 22. Reactor 20 is, however, in an unsaturated state and the solenoid unenergized. Upon operation of the initiating switch, winding 50 is disconnected from the rectifiers 57-60 but remains energized by a rectifier system 62, 64, 66, 68 in the A.C. circuit of reactor 22, which system is now connected to control winding 42 of reactor 20. This reactor is, thereby, saturated and the solenoid operated in consequence. After a certain movement of the press, limit switch 28 closes and connects control winding 40 across a rectifier 70 in the A.C. circuit of reactor 20, so that saturation is maintained until the limit switch again opens-irrespective of opening of the initiating switch. The solenoid deenergizes with opening of limit switch 28.