GB848300A - Improvements in or relating to excitation systems for dynamo-electric machines - Google Patents

Abstract

848,300. Synchronous machines. WESTING- HOUSE ELECTRIC CORPORATION. Jan. 8, 1959 [Jan. 10, 1958], No. 732/59. Class 35. In a synchronous machine in which the rotor field winding 4 is energized by an auxiliary generating winding 7 and rectifiers 10 rotating with the machine shaft to avoid the use of the usual field-current slip-rings, the magnitude of the field excitation is measured by measuring the voltage induced in a stationary auxiliary armature winding 18 by an auxiliary rotating field structure 15 excited in dependence on the main field current. This auxiliary field structure may be overhung at either end of or made integral with the machine rotor 5, or. it may fit over the machine-shaft. Time-constant resistors 17 are included. The fixed exciting winding 8 of the auxiliary generator is fed with.D.C. current controlled by a regulator 12 in dependence on the. output current in the stator winding 2 of the main machine by means of current transformers 13 and rectifiers 14. The voltage induced in the auxiliary armature winding 18 may be measured directly or, as shown, after rectification, by a voltmeter 20. This voltage is also fed to the voltage regulator through a transformer 21 to provide transient damping. The auxiliary field windings 22 may be connected in series or in parallel with the field winding 4, as shown.