Electrical Machines
In a DC machine

 current and emf in armature are alternating.
 current and emf at the terminals are alternating.
 emf in armature conductors and at the terminals is alternating.
 current and emf in armature are unidirectional

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Electrical Machines
Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then

 The magnitude will both increase.
 The magnitude of current will decrease but the power factor will increase.
 The magnetude of current will increase, but power factor will decrease.
 The magnitude of circuit as well as the power factor will decrease.

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Electrical Machines
The 3 - Φ induction motors are, by a very considerable margin, the most widely used AC motors as

  they have maximum efficiency and maximum starting torque.
  they have very good speed regulation.
  these are cheaper in cost, simple and rugged in construction.
  they are capable of operation under range of leading and lagging pf.

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Electrical Machines
A 10 kW, 230 V, dc shunt machine has four terminals brought out through four leads. For this machine

 both the windings have thin leads
 both the windings have thick leads
 armature winding has thick leads whereas field winding has thin leads
 armature winding has thin leads whereas field winding has thick leads

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