Patent GB-190520950-A (GB)
Title: Improvements in Controlling Devices for Electric Motors applicable to the Motors of Elevators or Lifts and the like
Filed: 1905-10-16
Granted: 1906-03-01
Abstract: 20,950. Otis Elevator Co., [Otis Elevator Co.]. Oct. 16. Lifts.-Relates to controlling-devices for electric lifts and the like, and more particularly to lifts operating between two floors only as in underground railways, and comprises means for (1) effecting re-establishment of the supply circuit should this become broken through any cause, and (2) preventing the return to fast speed after reversion to low speed. The motor circuits are supplied from the mains through a no-voltage switch 10. This switch, which also controls the circuit 14 containing the coils 115, 110 of the reversing-switch, is normally in engagement with its upper fixed contacts, but falls on to its lower contacts whenever the circuit of the solenoid 11 is broken by the safety devices, such as the handoperated safety switch 118, slack-cable switch 9, overwind switches 119, 122, and governor switch 12. The motor connexions are made by a handswitch 117, and they may be broken by reverse operation of the same switch or by switches 109 arranged in the path of the moving car. Operation of the switch 117 to engage, say, the contacts on the right-hand side causes, first, the coil 80 to be energized and the coil 60 to be inoperative owing to the break caused in its circuit. On the second step, the coil 115 is energized and the arm 28 rises to engage its upper fixed contacts, the arm 77 simultaneously engaging its lower contacts owing to the mechanical connexion of these portions of the reversing-switch. Current then flows from the upper contacts of the no-voltage switch 10 by the wire 7 to the contacts 17, 23, 54, 22, wire 37, contacts 38, 39, through the armatures 105, contacts 44, 45, wire 46, starting-resistances 35, 30, and the series field 40 to the negative main. Currents are also established through the shunt field 100 by the wire 37 and through the brake coil 116 by the wire 50. This coil, when energized, acts to lift a brake shoe out of contact with its friction pulley. On the third step the coils 49, 20 are energized. The circuit of the coil 15 is therefore broken at the contacts 101, 102, and the extra. field 70 and its resistances 90 are put out of action at the contacts 58, 59. Contact is also made at 103, 104, and the resistance 35 is shortcircuited. The coil 20 acts to short-circuit the resistances 30 and the series field 40 on the attainment of full speed. The motor is slowed down either by reverse motion of the handle or by operation of the switches 109. By this action, the resistance 35 is again introduced and the circuit of the coil 15 is completed, causing contact to be made at 58, 59 and the extra field 70 and its resistances to be brought into the motor circuit. Simultaneously, the circuits of the coils 49, 20 are broken by the coil 114, and the starting-resistances are prevented from short-circuiting. When the circuit of the coil 115 is broken, the power supply is cut off and the armatures 105 will be shortcircuited through the lower contacts of the arm 77 by the extra field 70, and current is also cut off from the brake coil 116. Furthermore, when the coil 80 is de-energized and its contact falls, the coil 60 causes the successive short-circuiting of the resistances 90. The short-circuiting is arranged to take place in the manner described in Specification No. 24,455, A.D. 1902. Should the no-voltage switch be opened, it falls on to its lower contacts, and the extra field 70 is immediately brought into circuit, the circuit of the coil 60 being completed by a wire leading from its contact to the contact 5. Pushes 120, 121 are arranged in the circuits of the overwind switches 119, 122, so that the switches may be short-circuited if either of them has opened the no-voltage switch in order to permit of reverse motion of the motors. The governor switch 12 and the slack-cable switch 9 are arranged to close automatically.