Assignment 8
List three advantages to a wound-rotor motor
1. Reversible, Dual Voltage, Dual configuration, High starting torque
2. low starting current, smooth acceleration, good for high-inertia loads,
3. Improved power factor as load increases, variable speed control, good regulation
Are the rotor windings or the stator windings brought out to slip rings in a wound-rotor
motor?
Rotor Windings
Is the external resistance applied to the rotor circuit or the stator circuit of a wound-rotor
motor?
Rotor Circuit
How should the direction of rotation of a wound-rotor motor be reversed?
Interchange any two line leads. (NEMA standard is interchange L1 & L3)
Will a wound-rotor assembly contain as many poles per phase as the stator assembly in a
wound-rotor motor?
Yes
How can the speed of a wound-rotor motor be controlled?
By adding and removing resistance to the rotor circuit (via an external speed
controller)
Will interchanging two resistor leads reverse the direction of rotation on a wound-rotor
motor?
No
The wound-rotor motor has _________ starting torque and ________ starting current
The wound-rotor motor has HIGH starting torque and LOW starting current
What components ride against the slip ring?
Brushes
List three applications for a three-phase wound-rotor motor.
1. Cranes, hoists, chair/ski lifts,
2. Gondolas, elevators,
3. Large compressors, large pumps
What is the electrical degree phase displacement of the coils in the rotor circuit of the wound-
rotor motor?
120 electrical degrees
What are the minimum number of slip rings required for a wound-rotor motor?
Three
What are the terminal leads connected to the slip rings on a wound-rotor motor labeled?
M1, M2, M3
What two components are used to hold the brushes in place and maintain an even pressure?
Brush holder and springs
What would be the lead identification numbers for the “C” phase windings of a 9-lead
wound-rotor induction motor?
T3, T6, T9
What are the minimum number of stator leads required for a 3-phase, single-voltage, dual-
configuration machine?
Six leads
What are the minimum number of stator leads required for a 3-phase, dual-voltage, dual-
configuration machine?
Twelve leads
What are the minimum number of stator leads required for a 3-phase, single-voltage, single-
configuration machine?
Three leads
What are the minimum number of stator leads required for a 3-phase, dual-voltage, single-
configuration machine?
Nine leads