GB476669A - Improvements in and relating to control systems for electrically operated winding and like mechanisms - Google Patents

Abstract

476,669. Automatic control systems. BRITISH THOMSON-HOUSTON CO., Ltd., and LIDDIARD, H. W. C. March 10, 1936, No. 7256. [Class 38 (iv)] [Also in Group XXXVII] Speed.-A Ward-Leonard control system for a winder motor 1 comprises a generator 2 having a field winding 2a supplied from an exciter 3 having, in addition to a main separately excited field winding 3a two supplementary field windings 3b, 3c energized only when a controller 10 has been operated to reduce the motor speed, the winding 3c being energized in proportion to the speed of the motor and opposing the field 3a, and the winding 3b being energized in proportion to the generator field current. Thus, at a stage prior to the end of a wind the motor speed is reduced to a value maintained substantially constant and independent of load conditions. The field 3c is energized from a generator 13 driven at a speed proportional to the motor speed, and the field 3b is connected in series with the generator field 2a, or, as shown, across a resistance 11b in circuit with this field. The controller 10 is operated by a torque motor or by electrohydraulic apparatus such as described in Specification 385,042, and the extent of its movement is controlled by cams coupled to the winder. Upon operation of a switch 17, a relay 8R is energized to energize a device 6 which lifts mechanical brakes, a device 5R which initiates movement of the controller 10, and a contactor 16 which interrupts " suicide " connections for the generator field 2a. The generator field 2a is also connected in the appropriate direction. As the controller moves the relay 8R is maintained by contacts 10f, and a rheostat 4 is operated by the winder to cut out resistance 9 from the exciter field 3a. A short-circuit across the resistance 9 is also completed by contacts 10e. Resistances 11a, 11b are gradually cut out of the generator field 2a, and the winder accelerates to full speed. The exciter 3 is initially effective to control the generator field, but as resistance 11b is cut out and resistance 12 cut in a transfer is made to a condition in which the field 3a of the exciter acts alone. After a certain movement of the winder the controller 10 begins to move to its off position to reinsert resistance 11a and decelerate the winder. This is followed by the reinsertion of resistance 11b and the reconnection of the field 13a of the generator 13 which is gradually strengthened. Thus, all three windings of the exciter are again effective and a constant low speed is maintained. As the controller continues to move to its off position, contacts 10e are opened and the winder gradually inserts resistance 9 in the exciter field 3a. The limit switch 15R subsequently opens to open the relay 8R. The controller 10 moves to its off position, the generator field 2a is de-energized, mechanical brakes are applied and " suicide " connections completed for the generator field. The controller 10 may be operated by hand for non- automatic operation and the system may be applied to double drum winders working from different levels.