Machines Flashcards
What is the main type of DC propulsion motor in use with the RN?
Shunt motor
What type of motor would use the squirrel cage rotor?
Three-Phase Induction Motor.
What material would be used for the conducting parts of the squirrel cage?
Copper or Aluminium or Iron
How are eddy currents minimised in a practical transformer?
Use a laminated iron core.
What would a single phasing motor wiring look like?
One broken wire, 2 intact wires
In a single phasing motor what would happen to the current in the other 2 wires?
become an increased 1-phase current.
describe the operation of a lightly loaded motor which develops a single phasing fault?
continue to run, but will not start if stopped.
Why is there a capacitor in a single phase induction motor?
To change the phase of the current in one of the windings.
What is produced in a single phase induction motor when the switch is closed? What happens a few minutes after the motor is switched on?
- A rotating magnetic field.
- As the motor gains speed the switch opens, disconnecting the capacitor.
Identify a type of single-phase AC motor.
Universal Motor.
What are the characteristics of an autotransformer when compared to other types?
It is cheaper and more efficient but provides no isolation.
List the FOUR types of three-phase transformer.
- Star Star
- Star Delta
- Delta Star
- Delta Delta
Which type of three-phase winding allows the connection of a neutral wire?
Star
What is the purpose of the neutral wire when used in a three-phase transformer?
To allow unbalanced currents to flow.
State the four conditions which must be satisfied before two AC generators can be paralleled.
- Same Terminal Voltage
- Slightly higher oncoming frequency
- Same Phase rotation
- In Phase.
