Patent GB-578122-A (GB)
Title: Improvements in dynamo-electric machines for remote transmission of angular motion and torque
IPC: G08C19/38
Filed: 1943-01-18
Abstract: 578,122. Electric distant control systems. BRITISH THOMSON-HOUSTON CO., Ltd., CHOUDHURY, S-U. A., MAGGS, A. H., and CLARK, L. J. Jan. 18, 1943, Nos. 936, 10009 and 16161. [Class 40 (i)] [Also in Group XXXVII]. In a resultant field system in which the transmitter comprises an armature, rotatable manually or by a separate motor, having a commutated winding fed with A.C. over stationary brush gear and providing a series of secondary voltages which are applied to a receiving selsyn of ordinary kind, the transmitter is provided also with one or more stator windings to enable the transmitter to be self driven when certain circuit changes are effected. The invention may be applied to any of the arrangements described in Specification 578.121. In the system shown in Fig. 1 (936/43), the known arrangement comprising armature 1, brushes b, tapped connections 4 and receiving selsyn 2, 3 is modified by the provision of a stator winding 12 on the transmitter displaced at an angle to the excitation axis, this winding when short-circuited at switch 13 causing the transmitter to be self driven in a direction and speed corresponding to the direction and value of the angle of displacement. In the system shown in Fig. 2 (936/43). the winding 12 is connected in series with a winding 14 energized by transformer action from the commutated winding. The switch 15 provides for reversal of the driving direction and when open permits manual operation. In other modifications, the winding 12 is connected in series with a shunt of the armature and winding 14 is open or closed for manual and self-driving operation respectively. A series winding may be short-circuited for manual operation to increase electrical "stiffness" of the system. Speed may be adjusted by resistance in the armature or stator circuits, or by a tapped transformer supplying the system. The armature winding may be arranged to operate simultaneously as a 4-pole transmitter armature and a 2-poie armature for self-driving, the two functions being non-interfering. A circuit arrangement for such a transmitter is shown in Fig. 2 (16161/43). The 4-pole transmitting function is provided by connection of one side of the supply to centre-tapped choke 25 having its ends connected to brushes A, C, and short-circuited brushes B, D connected to the other side of the supply. The choke is non-inductive for this function. The self-driving function is provided by a stator winding 28 in line with brushes B, C and a pair of windings 29, 30 at right angles thereto, one or other of which is used dependent on the direction of drive. The choke 25 is inductive as far as this function is concerned. The arrangements previously described may be modified to operate in this manner. The power handled by the transmitter due to circulation currents when the transmitter is run at speed may be reduced by including a reactance in the input to the transmitter corresponding in value to the total reactance of the rotor winding of the receiver. The reactance may be in the primary circuit of an input transformer or may be the leakage resistance of the transformer.