Electrical Machines
If Pi and Pc represent core and full load copper loss respectively, the maximum KVA delivered to load corresponding to maximum efficiency is equal to rated KVA is

 √(Pi/Pc)
 Pi/Pc
 Pc/Pi
 (Pi/Pc)2

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Electrical Machines
In a synchronous motor when the rotor speed exceeds the synchronous speed during hunting

  the damper bars develop induction motor torque.
  the damper bars develop synchronous motor torque.
  negative sequence currents are generated.
  the damper bars develop induction generator torque.

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