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

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

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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 of current will decrease but the power factor will increase.
 The magnitude will both 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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