GB757316A - Improvements in or relating to electric generators - Google Patents

Abstract

757,316. Exciting dynamo-electric machines. MACFARLANE, J. C., MACFARLANE, W. I., and MACFARLANE, J. W. July 16, 1953 [Nov. 12, 1952], No. 28488/52. Class 35. The output of a generator is regulated by means of a stabilizing generator excited from the generator current or voltage to be controlled and having saturated field parts 17 and unsaturated field parts 19 excited in series but acting in opposition on the armature so that they are balanced at a set output current or voltage, and any deviation causes a correcting voltage to be generated by the exciter and fed to the generator field, the output being set by a main source of excitation, suitably compounded for load, outside the stabilising exciter which only operates when the controlled current or voltage deviates from its set value. The stabilizing winding, fed by the stabilizing exciter, may be mounted on the interpolar axis of the main generator or its exciter as described in Specification 593,817. As shown in Fig. 4, where the invention is applied to the voltage regulation of a D.C. generator 27, the main excitation is derived from shunt field winding 28, compounded by brush shifting or by means of a series winding 30. The opposing field windings 18, 20 of the stabilizing generator 22 is excited from the load voltage and its output fed to an additional field winding 29. The generator may be of the type described in Specification 519,538. By the use of suitable series compounding on the main generator, the invention may be applied to the control of a generator driven by an ungoverned water turbine. By the use of a resistance shunt, the stabilizer may be used on constant current generators ; and A.C. generators, excited from their rectified output, may also be similarly regulated, through an intermediate exciter if necessary for large machines. The speed of response may be improved by the use of an injector transformer whose primary is connected in parallel with the stabilizer fed field winding 29 and the secondary is connected to a winding on the main pole of the stabilizer. Fig. 11 shows how the invention may be applied to the speed regulation of a motor 44. A tachometer generator 45, driven by the motor, feeds the opposing windings 18, 20 of the stabilizer 22 which in turn controls the motor field 46. Specifications 713,633 and 757,304 also are referred to.