GB454929A - Improvements in or relating to electric motor starters - Google Patents

Abstract

454,929. Actuating drum controllers. BROOKHIRST SWITCHGEAR, Ltd., Northgate Works, and HEATON, F., 4, Sandown Terrace, both in Chester. April 5, 1935, No. 10544. [Class 38 (iii)] Checked by motor current; with auxiliary switches.-Motor starter switchgear of the kind in which starting resistances R, Fig. 7, are cut-out successively by a step-by-step angular movement of a drum controller D from an initial position to a full-on position, a further step from which restores the drum to the initial position, is combined with a starter motor M, Fig. 7A, energized from the supply and geared to a shaft to give step-bystep movement of the drum, the shaft carrying timing switchgear K by which one terminal of the starter motor may be connected either through a normally closed auxiliary switch C2 on a main switch C in the main motor circuit to one pole P of the supply on the supply side of the main switch, or to the said pole P on the motor side of the main switch, the other terminal of the starter motor being connected to the other supply main N. Thus when the main switch C is closed and the drum D is in its initial position, the starter motor M is energized and rotates the drum to the full on position whereupon the timing switchgear K opens the circuit to the starter motor M. Upon operation of a stop switch Z the main switch C is opened and a circuit completed at the auxiliary switch K to energize the starter motor M to operate the drum D a further step into its initial position whereupon the timing switchgear K again disconnects the starter motor M. The controller is of the type described in Specification 363,046 and is arranged to be operated by handle mechanism which may be replaced by startermotor actuating mechanism. The drum D carries on its shaft 34, Fig. 6A, a coupling F1 which co-operates with an insulating coupling F and a coupling F2 on the actuating mechanism. This actuating mechanism in. the case of hand operation consists of a handle which is reciprocated to operate the drum through a pawl-and-ratchet mechanism and the coupling F2, the handle being capable of rotation to move the shaft 34 axially to close an auxiliary disc switch S. The startermotor actuating mechanism consisting of the motor, a mechanical brake Q, Fig. 4, a magnetic brake T, a worm 21, a worm wheel 22, a crank 24 connected by a rod 25 to lever 26 carrying a pawl 27 engaging a ratchet wheel 28 on the shaft coupled to the coupling F2, and the timing switchgear K, is formed as a unitary structure to be bolted to the starter switchgear in place of the handleactuating mechanism. The switchgear K consists of an insulating sleeve which carries a conducting sleeve suitably gapped and co-operating with three fixed contacts k<1>, k3, k4. In the case of power operation of the controller the switch S is kept in its operative position by a spring 34<1>, Fig. 6A, and links h1, h2, Fig. 7, are removed and a link m1 inserted. Upon actuation of a start switch B a main switch C is energized over contact s1 of the switch S, and maintained over auxiliary contacts c1. The main motor A is thus supplied through resistance R, and the starter motor M is also energized over contacts k3 of the switch K mounted on a spindle actuated by the motor M. The brake Q acting on the motor M is released by an electromagnet 18, Fig. 7A, and the controller D is actuated step-by-step through the pawl 27 and ratchet wheel 28 by the motor M under the control of the eddy-current brake T energized by the main motor current or a current proportional thereto. The energizing coil 21 of the brake T, Fig. 7B, may be connected across the last step of resistance R to be removed from the main motor circuit. When the controller D has removed all the resistance R the contact k3 opens and the motor M stops. Upon operation of a stop switch z the switch C is opened, and the auxiliary switch c2 completes a circuit through a contact k4 of the switch K to re-energize the motor M which moves the controller D a further step into its starting position whereupon the contact k4 interrupts the circuit of the motor M which stops. The switchgear is then ready for another start. The controller D may control the resistance R directly or through contactors, or it may be of the cam-shaft type. The resistance R may be armature resistance for a directcurrent motor or secondary resistance for an alternating-current slip-ring motor.