Page 339 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

• Separately Excited DC Motor
In a separately excited DC motor, the motor has separate electrical supplies to the armature winding and field
winding, which are electrically separate from each other. The operations of the armature current and field current
do not interfere with each other‘s actions, but the input power is their total sum.

Permanent Magnet DC Motor
A permanent magnet DC motor has an armature winding but does not have a field winding. The permanent
magnet is mounted on the inner surface of the stator core to produce the magnetic field. It has a regular armature
consisting of a commutator and brushes.

Permanent magnet DC motors are smaller and less expensive. They use rare earth magnets such as samarium
cobalt or neodymium iron boron.

Self Excited DC Motor
In self excited DC motors, the field and armature windings are connected and have a single supply source. The
connections are parallel or series with parallel made as shunt wound while the series version is series wound.

• Shunt
In a shunt wound DC motor, the field and armature windings are connected parallel to each other; this exposes the
field winding to terminal voltage. Though the supply is the same, the current for the field and armature windings
is different. The speed of a shunt DC motor is constant and does not deviate with varying mechanical loads.

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CITS : E & H - Electronics Mechanic - Lesson 205 - 222