GB326591A - Improvements in or relating to step by step mechanisms - Google Patents

Abstract

326,591. General Electric Co., Ltd., and Angold, A. E. Jan. 9, 1929. Travel for a fixed number of revolutions. - Motors 3, 4, Fig. 1, operating transformer tap-changing switches with a step-by-step motion are under the control of forward and reverse master push-buttons 36, 37 and a relay 43 which prevents a second step being initiated until a delay period has elapsed after the slowest motor has completed the previous step. The motors are stopped if they do not make the first part of a step in synchronism, and can be controlled individually by forward and reverse push-buttons 103, 104, if the associated double pole switch 44 is moved to the position shown in dotted lines. The action during one forward step is briefly as follows; closure of push-button 36 causes energization of relay 34 provided that contacts 87 of relay 43 are closed, these contacts close with a delay after relay 43 is de-energized and thus impart the required time-lag, and also provided that series connected sectors 21 on drums 11, 12 driven by the motors are in contact with the corresponding fingers thus ensuring that both motor devices are in a zero position. Closure of relay 34 completes at contacts 49, 51 energizing circuits for forward contactors 40 of the motors, and for brake release magnets 93. Just prior to the sectors 21 leaving their fingers and so interrupting the energizing circuit of relay 34, other series connected sectors 22 engage associated fingers, if both motors have made the first part of the step in synchronism, and energize relay 43, which opens contacts 87 to de-energize relay 34 and render both pushbuttons 36, 37 ineffective, to complete at contacts 78, 82 maintaining circuits over contacts 76 of contactors 40 for maintaining those contactors closed, and to complete at contact 84 a maintain. ing circuit for itself over sectors 130 on both drums, the sectors being connected in parallel. Thus, only after the last drum has made a complete revolution, is the relay 43 de-energized and push-buttons 36, 37 again rendered effective. A modified form of contactor 40 is shown in Fig. 2, the maintaining contacts 76 although closed upon energization of the contactor are not opened upon de-energization thereof unless coil 121, which is permanently connected to the supply, is energized. Normally this contactor operates similarly to that shown in Fig. 1, but should the supply fall during a step, the ccntacts 76 do not open and hence when the supply is restored the relay 43 and contactors 40 reclose and the step is completed. According to the Provisional Specification, the motors 3, 4 may be pneumatic motor with electric control.