GB718197A - Improvements in or relating to electric amplifying machines - Google Patents

Abstract

718,197. Exciting dynamo-electric machines. SIEMENS - SCHUCKERTWERKE AKT.-GES. Dec. 7, 1951 [Dec. 8, 1950; Jan. 31, 1951; Feb. 24, 19511, No. 28776/51. Class 35 A D.C. amplifying generator has two or more stages comprising separate armature windings of different pole numbers connected to separate commutators but influenced by the same stator poles which are excited by windings of the various pole numbers, the armature windings having the higher pole numbers being protected from circulating currents of the lower pole numbers by being either wave wound or else lap wound with adjacent brush pairs feeding separate load circuits. As shown in Fig. 3, the lap-wound two-pole winding 4 is connected to a commutator 5 engaged by brushes 6 feeding the four-pole exciting windings, while a four-pole output winding 3 is connected to a commutator 1 engaged by load brushes 2. The two armature windings may be placed in separate or common slots. The stator poles 7 carry two-pole separately excited windings 9 which pro-. duce a voltage between brushes 6 which in turn energizes four-pole exciting winding 8 to excite the main armature winding, commutating poles being used if necessary. If desired, an additional stage may be introduced by the use of short-circuited quadrature brushes 10, in which case a two-pole armature-reaction compensating winding 11 is placed in slots in the polefaces. The two commutators may be replaced by rectifiers connected to phase tappings on the two windings, and if desired dry rectifiers may be used which enable the armatures to be stationary while the poles rotate. Alternatively the tappings may be used to supply a single or polyphase alternating current. For use as an exciter, the machine may be made selfexciting by feeding the two-pole field windings 9 in parallel with the four-pole field windings 8 from the brushes 6. Alternatively both armature outputs may be connected in series to the four-pole field winding. The degree of self-excitation may be of such proportions that it is controlled by a very small separate excitation current. By the use of a controlling rheostat in series with the four-pole winding 8, the main output of the machine may be varied without affecting the output of the two-pole armature winding which may be tapped to provide a constant-voltage A.C. output. The voltage may be additionally stabilized by putting saturable shims under the poles. If desired the two- and four-pole fields may be excited separately so that the four-pole armature winding provides a D.C. output while the two-pole winding generates A.C. which may be rectified to feed the four-pole field windings. A machine is described having three stages comprising a four-pole commutated or rectified A.C. armature winding feeding a self-exciting winding and an eight-pole field winding, an eight-pole commutated armature winding feeding a sixteen-pole field winding, and a commutated sixteenpole armature supplying the output current.