| 摘要 |
568,155. Dynamo - electric machines. FLETCHER, G. H., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. Aug. 4, 1943, No. 12618. [Class 35] [Also in Group XXXVII] An exciter for one or more traction motors has at least part of its excitation dependent on the motor armature current and a non- linear resistance is provided in the field or armature circuit of the exciter. In the form shown, exciter windings 14, 18 strengthen the motor field in. response to rising speed and armature current respectively, while main winding 9 of the exciter 4 is connected across the motor interpole windings 2 in series with a resistance 10 having a negative resistance-voltage characteristic, and such resistances may also be in the circuits of windings 8, 14, 18. Winding 14 is fed by a tachometer dynamo 13 driven at a speed proportional to the main motor speed and which generates an effective voltage only at a predetermined high speed. Winding 18 is connected to a transformer 16 so that it is effective only when the main current changes rapidly. Windings 14, 18 are optional and the exciter may also have a field winding connected across the motor terminals or a shunt winding. Alternatively, winding 9 may be on a sub-exciter feeding the field of a main exciter. The motor 1 may also have a series winding.
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