GB749894A - Excitation system and control therefor - Google Patents

Abstract

749,894. Synchronous machines. PESTARINI, J. M. Nov. 29, 1954 [Dec. 22, 1953], No. 35635/53. Class 35. The field winding 20 of a synchronous motor or generator S is excited in response to load changes by a metadyne exciter M2 which is controlled by a pilot metadyne exciter M1, both machines being fed at their primary brushes a, c from battery Bt through a switch H which may be operated to shortcircuit their primary axes to enable them to act as generators. A device 30 connected to the alternator output is responsive to load changes and produces control current Ip, fed to pilot exciter field winding 5 and, if desired, a further error current Ie fed to main excitor winding 98. Field winding 6, which opposes winding 5, and may be combined with it to form a single winding, is fed from an outside source with a current Ir proportional to the desired value of the output of generator S, so that the output of the generator is proportional to the resultant energization of these two windings. A transformer F eliminates induction between field windings. Field windings 1 and 90 are connected in series with the primary brushes of excitor M1 and serve to oppose and augment respectively the armature ampere-turns due to the primary current. Shunt excitation winding 3 produces a voltage across primary brushes a, c substantially equal to the voltage of battery Bt, while secondary current armature reaction is compensated by winding 9. Further control windings 7, 77 may be used if desired. The output of the exciter M1 is fed to field winding 25 of exciter M2, which also may have a shunt winding 23 backing the battery voltage. Field winding 21 creates an E.M.F. opposing the primary current while winding 22 which is traversed by secondary current and produces a flux opposing that current while winding 29 produces under-compensation for secondary current. In a modification, greater stability of operation is achieved by the use of two similar exciting systems feeding alternator field coils in quadrature. The control currents Ip and Ir may be controlled by auxiliary generators.