Electrical Machines
A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping

 Rf maximum and Ra minimum
 Ra maximum and Rf minimum
 Ra minimum and Rf minimum
 Ra maximum and Rf maximum

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Electrical Machines
Two 3-phase AC generators are such that one has twice the linear dimensions of the other. The field windings of each are excited to give identical sinusoidal air-gap flux density waveform. Both have the same number of stator slots and identical winding patterns. The conductor/slot in a big generator is K times that of the smaller one. The value of K to get equal no load voltage at same frequency is

 1/4.
 8.
 4.
  1/2.

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