Electrical Machines
A series generator is connected in series to a feeder having 0.5Ω resistance to boost the voltage. The induced voltage is given by Eg = 0.6Ia, Ra = 0.2Ω and Rs = 0.3Ω. Find the voltage boosted by the generator, when delivering 400 Amp?

 30 V.
 60 V.
 90 V.
 40 V.

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Electrical Machines
Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements,

 2, 3 and 4 are correct
 1, 2 and 4 are correct
 1, 2 and 3 are correct
 1 and 4 are correct

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Electrical Machines
In DC machines, the interpoles are provided

 to counteract the reactance voltage and the cross-magnetizi
  both (B) and (C).
 to counteract demagnetizing effect of armature mmf in commutating zone.
  to make commutation spark less.

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