What are DC Motors?
DC Motors have a place of pride as far as electrical drives are considered. The
simplicity, and linearity of the control method make them highly preferred machines in
precision drives. Despite the great advancements in a.c. drives these machines are still
sought after by industries. Apart from the high precision application, they are preferred in
stand-alone systems working on batteries and high-speed drives off constant voltage mains.
After the field is excited if we pass a current through the armature the rotor experiences
a torque and starts rotating. The direction of the torque can be readily obtained from the
law of interaction. These moving conductors cut the field and induce emf, usually called the
’back emf’ according to Lenz’s law, and act as a sink of electrical power from the electrical
source. This absorbed power appears as mechanical power. The converted mechanical power
should overcome the frictional and iron losses before useful work could be done by the same. |
| DC Motor |
Types of DC Motors:
DC motors are of three types:
- DC Series motors
- DC Shunt motors
- DC Compound motors
DC Series Motors:
In series-motor, field-winding is connected in series with an armature and the whole load current passes through it. Series winding turns are made of a thick conductor as they have to carry a large amount of current. These motors are used for traction and mining purposes.  |
| DC series motor |
DC Shunt Motors:
In
shunt motors, the field winding is connected in a shunt and it is made of a thin conductor so that the current passes through it does not change and flux remains constant.
 |
| DC Shunt motor Overhaul |
DC Compound Motors:
Compound motors are similar to shunt motors but an additional series winding is provided. These motors are classified into 2 types:
- Long Shunt Compound Motors
- Short Shunt Compound Motors
 |
| DC Compound Motor |
