The squirrel cage
induction motor is the most popular and widely used AC motor because it is very
cheap, efficient, robust and reliable. The slip ring motors are rarely used in
industries because it has several disadvantages like frequent maintenance, high
copper loss.
Main difference :
The slip ring motor has an external resistance circuit for controlling the
speed of the motor whereas the squirrel cage motor not possible to add any
external circuit because, at the end of the ring, the bar of the motor is
permanently slotted.
Difference :
- A slip ring is a motor whose rotor is wound type
whereas the squirrel cage motor has a squirrel cage type rotor.
- The rotor of the slip ring motor has a parallel slot
cylindrical core and each slot consists of each bar while the slot is not
parallel in case of the squirrel cage motor.
- The slip ring motor is also called a phase wound rotor
and the name of the squirrel cage motor is cage motor.
- The slip ring motor consists of a slip ring and brushes
which is complicated whereas the construction of the squirrel cage motor is simple.
- At the start, the slip ring motor the rotor resistance the starter is used, while the slip ring motor doesn't require any starter.
- The phase wound motor consists of external resistance
circuit, on the other hand, whereas no internal resistance circuit
can be added in the squirrel cage motor due to the permanent slotting of
their rotor bars.
- The starting torque of the slip ring motor is very high
and low in case of squirrel cage motor.
- Compared to the squirrel cage motor, the maintenance
cost of the slip ring motor is high because the slip ring motor consists
of brushes and rings.
- Compared to the squirrel cage motor, the copper loss is
more in the slip ring engine.
- Compared to the squirrel cage motor, the slip ring motor has a low power factor.
- The motor of the slip ring has brushes to transfer
power while the motor of the squirrel cage is brushless.
- The efficiency of the slip ring motor is low and high
in the squirrel cage motor.
- The resistance circuit is used to control the speed of
the slip ring motor whereas impossible to control the speed of the squirrel cage motor.
- The wound rotor phase price is high because it is made
up of brushes and the squirrel cage motor is cheap.
- The starting current of the slip ring motor is small
because it is regulated by the resistance circuit while it is high in the squirrel cage motor.
- The slip ring motor is mostly used in places where high
starting torque is required like a hoist, cranes and the squirrel cage
motor is used in a drilling and lathe machine.
- Compared to squirrel cage motor, overloading capacity is high in the slip ring motor and is smoothly running under heavy loads.
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