Patent GB-483163-A (GB)
Title: Improvements in electric motor control systems
IPC: F23D3/00
Filed: 1936-11-18
Abstract: 483,163. Master control of D.C. motors; electric systems for controlling lifts ; dynamos. WAYGOOD-OTIS, Ltd. Nov. 18, 1936, No. 31561. Convention date, June 15. [Class 38 (iii)] [Also in Groups XXXV and XXXVIII] Varying E.M.F.-In an elevator system, a direct-current driving motor is supplied from a generator having at least two field windings, one of the field windings being connected across the generator armature for generating a voltage for application to the motor, and the other being connected across the generator armature in opposition to the first, for slowing down the motor. With the car at the first floor and its gate open, door look contacts 292 and gate contacts 291 are open, contacts 103 being closed to energize a relay DC111 which opens contacts DC106 to de-energize a relay TS113. If a call is made at the third floor a relay 3UF135 is operated to energize the third floor controller contact 147 and an up-direction switch relay UR190. The relay UR190 energizes a starting relay MSR91 for a motor-generator set comprising a motor 40 driving a generator 437. An exciter 235 driven by the motor 40 or a separate motor 42 and supplying the separately excited generator and motor fields and various control relays is also started. As the exciter voltage rises a series field relay SF266 shortcircuits the generator series field 433, and when the motor generator set has been started contacts MR260 are closed to energize a potential relay P261 which removes one of two short-circuits from the generator shunt field 414, and energizes a slow-down relay SL311. The relay SL311 energizes a coil PM341 to retract pawls from a floor controller which is of the form described in Specification 297,801, [Class 78 (ii)], and also energizes a gate control relay GR302. This gate control relay energizes the time relay TS113 and a gate close switch GC382, the latter energizing a time cancelling relay TC105 which de-energizes the relay SL311 and effects closing of the gate. Upon closure of the gate, the hatchway door is locked and relays FB294, U286 and UA287 are energized. The floor controller up-brushes 195, 196 are thus energized and auxiliary reset brushes 206, 211, 214 disconnected. The relay FB294 connects a voltage relay VR445 across the generator armature, disconnects the generator demagnetizing winding 427, and releases a brake 403. The relay U286 removes the remaining short-circuit from the generator shunt field 414 and completes a circuit for the separately excited field winding 394 of the generator through resistance 392. Thus the car is started, the relay U286 also energizes slow-down relays FSR347 and SSR353, the former short-circuiting the resistance 392 to increase the generator voltage and the speed of the car. When the voltage applied to the motor reaches, say 10 volts, a coil NR448 connected across the generator armature assisted by a coil NR386 operates a relay to de-energize the relay SF266 which inserts the generator series field 433, and also operates a relay FS367 which connects the generator shunt field 414. The generator is now self-exciting and builds up its voltage, and when this voltage reaches a certain value the relay VR445 disconnects the relay coil NR448. A relay LSR432 connected across the generator interpole winding 435 is set to operate when the load on the motor is equal to an empty car being lowered. Its operation energizes a self-maintaining load relay LS377 to short-circuit resistance 413 in the generator shunt field. When the car approaches the third floor the contact brush 196 engages the contact 147 to energize a relay CP222 which energizes a self-maintaining relay PH336. When the brush 196 disengages the contact 147 a switch 152 is opened to de-energize the relay UR190 which de-energizes the relay MSR91, the motor-generator controller now being under the control of the time relay TS113. The brush 196 also de-energizes the relay CP222 to energize, over contacts of the relay PH336, a restoring coil SL330 of the relay SL311. This relay SL311 then de-energizes the relay PH336 and the coil PM341 so that the up-pawl of the floor controller engages the up-third stopping collar, and the relay FSR347 is de-energized. The latter then inserts resistance 392 in the circuit of the generator field 394 and connects the generator demagnetizing field 427 across the generator armature in opposition to the shunt field. Thus the voltage of the generator and the car speed is reduced. The circuit of the field 427 includes resistance 416 and if the load relay LS377 has not operated, a resistance 426. If the load relay is not operated, the relay FSR347 re-establishes the circuit for the relay SF266 which again shortcircuits the generator series field 433. The field 433 is not short-circuited if the load relay is operated. The up-pawl of the floor controller engages the up-third stopping collar and when a certain point is reached the relay SSR353 is de-energized to short-circuit the resistance 416. The strength of the demagnetizing generator field is now nearly equal to that of the shunt field, the generator voltage falling to a low value and the relay VR445 opening. When another point is reached the relay FS367 is de-energized to disconnect the generator fields 427, 414, the field 394 in series with the resistance 392 remaining energized and effecting the final slow speed operation. If the relay SF266 is not de-energized by the load relay it is de-energized when the relay FS367 is de-energized and renders the generator series field 433 effective. Just before the required floor is attained the relays U286, UA287 and FB294 are de-energized. Thus the generator field 394 is disconnected and the brake 403 applied. The generator demagnetizing field 427 is also connected when the relay FB294 is de-energized and connteracts the residual magnetism of the generator, the series field being short-circuited by energization of the relay SF266. The relay FB294 when deenergized also energizes reset brushes 206, 211 and 214 of the floor controller, and de-energizes the gate relay GR302 to effect operation of the gate opening mechanism. When the gate is open a limit switch 357 opens and the time relay TS113 is de-energized. The time which elapses after de-energization of the time relay before its contacts open permits the passenger to press a car button for the desired destination. A time-cancelling relay enables the car to start in the same direction without waiting for the expiration of the full time interval of the relay TS113. If no calls are to be responded to, upon the expiration of the time interval, the relay switches off the motor-generator and the exciter. For emergency stops a switch 255 is operated which causes the generator shunt field to be disconnected and the demagnetizing field to be connected. The shunt field is shortcircuited to reduce the abruptness of the deceleration. The generator series and separately excited fields are also de-energized and the brake applied. Specification 483,194 also is referred to.