WorksheetsModule 7745 Chapter G
Total questions: 7
Worksheet time: 4mins
What type of machine is described below?
"An electrical supply is fed to the stator winding which produces a rotating magnetic field. Electromagnetic induction between the stator and the rotor produces torque, which causes the rotor to rotate."
AC Induction Motor
DC Induction Motor
AC brushless Generator
DC Generator
AC Brushed Generator
With respect to induction motor which type of rotor is described below?
The rotor consists of a laminated iron core with conductor bars located in longitudinal slots around the circumference.
Cage type rotors
Wound rotor
Salient pole rotor
Cylindrical Pole Rotor
If a single phase was to fail in a 3 phase induction motor prior to the motor turning, what would occur with the application of ac power?
The motor would fail to run.
The motor would run but in an uneven manner.
The motor would only move to align itself with the Magnetic Neutral Axis
The motor would only move to align itself with the Geometric Neutral Axis
If a single phase was to fail in a 3 phase induction motor while the motor is running a light load, what would occur?
The motor would fail to run.
The motor would run but in an uneven manner.
The motor would only move to align itself with the Magnetic Neutral Axis
The motor would only move to align itself with the Geometric Neutral Axis
Why is single phasing hazardous?
Current will increase in the remaining phases, potentially overheating the windings, burning out the motor.
The magnetic field would collapse over one winding. The motor would change direction suddenly, potentially shearing the torque shaft of the load.
The chopper circuit used to start the motor would lose its timing circuit. Resulting it a constant DC being supplied on startup. This causes a spike in current, leading to overheating & burning out the motor.
The open circuit of a diode from the output of the exciter armature cause the dc current in the main exciter field to drop. therefore the output voltage decreases, leading to a loss of power.
Current will increase in one of the remaining phases, causing an unbalanced system. This leads to overloading of the output circuit.
In a 2 phase induction motor what is the relationship between the reference windings and the control windings?
The reference windings are mechanically 90o and electrically 90o apart from the control windings.
The reference windings are mechanically 90o apart and electrically in phase with the control windings.
The reference windings are mechanically 90o and electrically 180o apart from the control windings.
The reference windings are mechanically 180o and electrically 90o apart from the control windings.
In a servo motor the loss of the control winding would...
cause the motor to stop instantly.
remove the drive of the motor, causing it to stop due to friction.
cause the motor to loss control so would accelerate to maximum speed.
cause the motor to reverse direction.
