Wound rotor motor

Wound rotor motor

An induction motor with the squirrel cage conductor bars replaced with coils of wire, and with added slip rings, brushes, and resistor circuit.

difference between a SCM and a WRM is?

The conductor bars are replaced with coils of wire

stator construction of WRM

Windings with a core that are 120 degrees apart and can be wound in either wye or delta

• same structure as SCM stators

Rotor construction of WRM

Laminations stacked together and placing insulated coils of wire in the slots instead of the solid conductor bars used in SCM

• presence of coils of wire

what is connected with the rotor construction of a WRM

Wye-External resistors through brushes and slip rings

Purpose of external resistors in a wound rotor motor

To control the rotor current and improve starting torque, allowing for better speed control.

Max torque is produced when

C) max resistance is connected to the rotor

High resistance rotor develops a high starting torque at low starting current because the phase angle in the rotor is close to _____ degrees

C) 0

To gain max starting torque the motor is started with _____ rotor resistance

A) Maximum

The resistors must be removed from the rotor circuit after the motor is up to speed T/F

A)T

Increasing the resistance WHILE the motor is running ______ the current

B) decreases

Wound rotor motor is know to have ______ starting current

B) Low

WRM has _____ efficiency

B) bad

Which of the following motors has slip rings and external resistors?

B. Wound rotor motor

What is a key advantage of a wound rotor motor at start-up?

C. High starting torque

Squirrel cage motors typically have which of the following characteristics?

D. Simple, rugged construction

Which motor allows speed control by adjusting rotor resistance?

C. Wound rotor motor

Wound rotor motors are commonly used in:

C. Cranes and hoists

Why is the efficiency of wound rotor motors generally lower than squirrel cage motors?

C. Energy is lost in external resistors

Which motor is most suitable for fixed-speed industrial applications?

B. Squirrel cage motor

In a wound rotor motor, increasing rotor resistance will:

D. Improve speed control at low speeds