Patent GB-118324-A (GB)
Title: Improvements in Switch Gear for Starting and Controlling Electric Motors.
Inventor: HIRST JOHN ARTHUR
IPC: H02K17/30
Filed: 1917-08-22
Abstract: 118,324. Hirst, J. A., and Brook, P. S. Aug. 22, 1917. Controllers, actuating-mechanism for; controllers with " no volt " and " overload " release.-A motor controller comprises a circuitbreaker having a " hold-on " coil and one or more sets of switches adapted to control the stator connexions on the star-delta or autotransformer principle or the resistances in the rotor circuit of an alternating-current motor, or a resistance in the armature circuit of a direct-current motor. The circuit-breaker is closed by cam rollers mounted upon a shaft which is geared to the shaft or shafts of the controlling switch or switches: while the shafts are operated in one direction only, through pawl and ratchet mechanism, to close and open the circuits. The operating handle or a part thereof is given a secondary movement to close the circuit of the " hold-on " winding of the circuit breaker; while a second switch is provided to close this circuit when the controller is in its " full-on " position in order that the circuitbreaker may open if the controller is not fully operated. A visual or audible indicator is provided to denote the " full-on position of the' controller. The controller may be provided with an overload release circuit-breaker. In the arrangement shown in Figs. 1, 2, and 9 the contact-arms of a circuit-breaker B are mounted upon a shaft b adapted to be rotated through toggle mechanism D and cam rollers c<1> mounted on arm c<2> carried by a shaft C<1>. The contactarms of a switch E, adapted to connect the stator windings w<1>, w<2>, w<3> in star connexion, are mounted upon a shaft c adapted to be rotated through toggle mechanism D and cam rollers c<1> mounted on arms c<2> carried by a shaft c<3>, while the contact-arms of a switch F, adapted to connect the stator windings w<1>, w<2>, w<3> in delta, are mounted upon a shaft f adapted to be rotated through toggle mechanism D and cam rollers c<1> mounted on arms c<2> carried bv a shaft C<2>. The circuit breaker B is provided with a " hold-on " magnet b<4> and, when set, the members of its toggle mechanism D are not in alinement. The toggle mechanisms D of the switches E and F are in alinement when these switches are closed and the switches E and F are opened by a further rotation of the shafts C<3>, C<2> thereby causing additional cam rollers c<4> mounted on the shafts C<3>, C<2> to engage cam rollers d<3> on toggle mechanism to trip the switches. The shafts C<1>, C<2>, and C<3> are connected by chain-gear G<2>; while the shaft C<2> is made hollow to receive a sliding member k<1>, Fig. 7, carrying the movable member K of a switch k<2>, K, k<3>, Figs. 1, 7, and 9. The shaft C<2> is rotated by a handle P mounted upon. a rotatable annulus N', Figs. 7 and 8, carrying an operating pawl n' engaging a ratchet-wheel M secured to the shaft C<2>. The reverse movement of the shaft C<2> is prevented by means of a pawl n<5> and at ratchet-wheel n<6>. The ratchet-wheel M carries an indicating drum n<7> which is seen through a window n<8> in the casing N tc inform the operator when the controller is in its " fullon " and " off " positions. The visual indicator may be replaced by a single-notch ratchet provided with a clicking pawl. The switch k<2>, K, k<3> is closed by depressing a knob k<4> on the handle P against the action of a spring k<5> thereby causing a cam surface k<6> to engage one end of the rod k<1>. The switch k<2>, K, k<3> controls the circuit of the " hold-on " coil b<4> of the circuit-breaker B and this circuit remains completed through a switch q<1>, Q, q<2>, Fig. 9, when the controller is in its " full-on " position. To start the motor, the handle P is reciprocated to rotate the shafts C<1>, C<2>, C<3> and the knob k<4> is depressed to close the switch k<2>, K, k<3>. The circuit-breaker B is first set and afterwards the switch E is closed to connect the mains to the stator windings in star connexion. Further rotation of the shafts causes the switch E to open and the switch F to close simultaneously to connect the stator windings in delta connexion. The switch q<1>, Q. q<2> is simultaneously closed to complete the circuit of the " hold-on " coil b independently of the switch k<2>, K, k<3> so that the coil b remains energized when the handle P is released. In the modification shown in Fig. 10, the stator windings w<1>, w<2>, w<3> are connected to the mains through circuit-breaker B while sections of a resistance R in the rotor circuit R<1> are gradually cut-out by means of switches S successively operated by the rotation of the shaft C. Resistances in the circuits of the other rotor windings r<2>, r<3> are similarly controlled by shafts geared to the shaft C.