PowerPoint® Presentation
Chapter 6
Wound-Rotor Motors
Wound-Rotor Motor Construction •
Stator Construction • Rotor
Construction • Operating Principles •
Starting and Torque • Speed Control
• Starters • Regulators
Chapter 6 — Wound-Rotor Motors
The stator of a wound-
rotor motor is the same as
the stator of a squirrel-
cage induction motor.
Chapter 6 — Wound-Rotor Motors
The rotor of a wound-rotor
motor is constructed by
placing insulated coils of
wire in the slots, instead of
the solid conductor bars
used in the squirrel-cage
induction motor.
Chapter 6 — Wound-Rotor Motors
Wound-rotor stator
windings are wye
connected, with the free
end of each winding
connected to a slip ring.
Chapter 6 — Wound-Rotor Motors
A brush is held in a
brush holder and is
free to move up and
down in the holder.
Chapter 6 — Wound-Rotor Motors
The resistors are switched to add or subtract the
resistance from the rotor circuit.
Chapter 6 — Wound-Rotor Motors
The secondary resistors
are connected through
the slip rings and
brushes to the terminals
M1, M2, and M3.
Chapter 6 — Wound-Rotor Motors
Resistance is reduced as the motor accelerates in
order to shift the point of maximum torque.
Chapter 6 — Wound-Rotor Motors
Starters usually have
one or more timers
used to automatically
remove resistance
from the rotor circuit.
Chapter 6 — Wound-Rotor Motors
A drum switch is a
rotating control device
used to switch
resistors in or out of a
wound-rotor circuit.
Chapter 6 — Wound-Rotor Motors
A rheostat uses a three-wire control circuit to start the
wound-rotor motor.