Patent GB-753556-A (GB)
Title: Improvements in or relating to electric power systems
IPC: H02P5/68
Filed: 1954-11-15
Abstract: 753,556. Exciting dynamo-electric machines. PESTARINI, J. M. Nov. 15, 1954, No. 33058/54. Class 35. [Also in Group XXXVII] A system comprising a motor controlled by a metadyne exciter and a speed-responsive dynamo on the same shaft is arranged to produce a controlled motor torque which is constant or proportional directly or inversely to the speed or a function of speed. As shown, the system comprises a constant voltage supply line L, a generator 11 and a motor 13 connected on the same shaft with exciter metadyne 15 and speed regulator dynamo 16. The secondary brushes b, d of the generator feed the primary brushes a, c of the motor, and also shunt windings 20, 21 on the two axes of the generator. Under-compensation is provided by series winding 18, control winding 17 is fed through a rheostat from the mains L, and winding 19 is energized by the secondary output of the exciter 15. Motor excitation winding 22 may be excited from secondary brushes b, d of exciter 15 through selective operation of switches 26, 27. Series winding 23 may produce complete or partial compensation for load current by means of tappings (not shown). Winding 24 is fed through a rheostat from the mains L and winding 25 is fed from regulator dynamo 16 whose critical build-up speed is set by rheostat 30 and whose voltage is in opposition to the mains voltage. The exciter dynamo is excited solely by mains voltage applied to its primary axis. With switches 26, 27, 28 open, the generator 11 supplies a constant primary motor flux modified by the excitation of winding 24. This constant flux induces a voltage between secondary brushes b, d which is proportional to the speed, which produces the secondary flux also proportional to the speed. The motor torque is thus proportional to its speed. If rheostat 31 is shorted, speed variations will produce wide variations in the resultant current Ip from the regulator dynamo fed to winding 25, which thus tends to produce a fixed motor speed equal to the critical speed of the dynamo. If rheostats 31, 17a, 24a are shorted, switch 28 is closed and switches 26, 27 used to connect winding 19 to the output of exciter 15 which provides a current inversely proportional to its speed, the motor torque will be inversely proportional to its speed. If rheostats 24a, 31 are open-circuited, rheostat 17a is set, switch 28 is closed and switches 26, 27 connect winding 22 to the exciter 15, the generator 11 supplies constant current and the motor torque is constant at any speed. If desired, combinations of these characteristics may be obtained. The rheostat 30 may be continuously operated to control the speed as a function of another variable, e.g. time. In a modification, the dynamo 16 feeds a winding on the exciter. In a further modification, the metadyne generator is replaced by a metadyne transformer fed from the mains and the metadyne motor is replaced by a simple machine, this arrangement being capable of producing constant speed or a torque which is constant, or proportional to the inverse or inverse square of the speed. In a further modification the metadyne generator is dispensed with and the motor supplied from two separate D.C. sources. The critical speed of dynamo 16 may be automatically controlled. Specification 420,167 is referred to.