Electrical Machines
The synchronous reactance( Xs) is the

 reactance either due to armature reaction or leakage flux
 reactance due to leakage flux
 reactance due to armature reaction of the machine
 combined reactance due to armature reaction and leakage flux

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
In case of 3 - Φ IM, plugging means

  locking of rotor due to harmonics.
  interchanging two supply phases for quick stopping.
  pulling the motor directly on line without a rotor.
  starting the motor on load which is more than the rated load.

ANSWER DOWNLOAD EXAMIANS APP