|
Parameters
|
Squirrel Cage
Induction Motor
|
Slip Ring
Induction Motor
|
|
Rotor
|
Copper bars
are slotted in the rotor and these bars are short circuited from both ends by
end rings
|
Three phase
winding is slotted in the rotor similar to stator winding
|
|
End rings
|
Two
end rings are used on both side of rotor
|
End
rings are not used
|
|
External
Resistance
|
As the rotor
is short circuited by end rings, extra resistances are not connected.
|
External
resistance can be added from rotor side
|
|
Slip rings
and brushes
|
Not
used
|
Three
slip rings and brushes are used as per current capacity at rotor side
|
|
Starting
torque
|
Moderate
starting torque. The starting torque cannot be increased.
|
High starting
torque is achieved by adding external resistances to rotor side.
|
|
Speed control
|
Speed
control from rotor side is not possible because the rotor itself a closed by
end rings.
|
Speed
control is possible from stator and rotor side. The speed control from rotor
side is done by rotor resistance starter.
|
|
Copper losses
|
Better space
factor for rotor slots, shorted over hang and smaller copper loss
|
Large over
hang resulting higher copper loss
|
|
Cooling
condition
|
Cooling
condition is better because it has bare end rings thus large space available
for fan
|
Cooling
condition is affected by some times sparking between slip rings and brushes
|
|
Overload
capacity
|
Better
overload capacity
|
Low overload
capacity as compared to squirrel cage induction motor
|
|
Power factor
|
Better
power factor due to smaller rotor overhang
|
Comparatively
high power factor
|
|
Pull out
torque
|
High
|
Low
|
|
Maintenance
|
Low
|
High
|
|
Construction
|
Simple and
robust
|
Complicated
|
|
Cost
|
Low
|
High
|
|
Efficiency
|
High
|
Low as
compared to Squirrel cage Induction Motor
|
|
Applications
|
Fan,
printing machine, lathes, drill machine, blower etc
|
Lift,
compressor, crane, hoist etc.
|
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