91. The phenomenon of oscillation of the rotor of a synchronous motor about its equilibrium position corresponding to new load on sudden throwing off or increasing of load is called the
- swinging
- crawling
- hunting
- cogging
92. In a synchronous motor, hunting can be reduced to minimum possible by
- providing damper winding in the rotor pole faces
- using a flywheel
- designing the motor for adequate synchronizing power
- any of the above methods
93. The damper windings also called the squirrel cage windings or damper grids
- are provided in a synchronous motor to make it self-starting and to prevent hunting
- consists of short-circuited copper bars embedded in the field pole faces of a synchronous motor
- are provided on the stator of a synchronous motor for improving the power factor
- both (1) and (2)
94. In a synchronous machine, damper windings are used to
- help in starting as a motor
- run it as an induction motor
- help in starting as a motor and to reduce hunting
- increase efficiency
95. When a synchronous motor is running at synchronous speed, the damper winding produces
- damping torque
- eddy current torque
- torque aiding the developed torque
- no torque
96. In a synchronous motor, when the rotor speed exceeds the synchronous speed during hunting
- the damper bars develop synchronous motor torque
- the damper bars develop induction motor torque
- the damper bars develop induction generator torque
- harmonics are produced in the armature circuit
- negative sequence currents are generated
97. During hunting of synchronous motor
- negative phase sequence currents are generated
- harmonics are developed in the armature circuit
- damper bar develops torque
- field excitation increases
98. Synchronous condenser means
- a synchronous motor with capacitor connected across terminals to improve pf
- a synchronous motor operating at full load with leading pf
- an overexcited synchronous motor partially supplying mechanical load, and also improving pf of the system to which it is connected
- an overexcited synchronous motor operating at no load with leading pf used in large power stations for improvement of pf
99. Which of the following devices can be used as a phase advancer?
- 3-phase induction motor squirrel cage type
- 3-phase induction motor slip-ring type
- Synchronous motor working at leading power factor
- Synchronous motor working at lagging power factor