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Starting Characteristics of Squirrel Cage Induction Motors

Starting Method

 Voltage
at Motor		 Line
Current		 Motor
Torque
Full-Voltage Value 100 100 100
Autotransformer

80% tap
65% tap
50% tap
 

80
65
50

  

64*
42*
25*

  

64
42
25
Primary Resistor Typical Rating 80 80 64
Primary Reactor

80% tap
65% tap
50% tap
 

80
65
50

  

80
65
50

  

64
42
25
Series-Parallel 100 25 25
WYE-DELTA 100 33 33
Part-Winding (½ – ½)

2 to 12 Poles
14 and more Poles
 

100
100

  

70
50

  

50
50

Soft start is also available using solid-state controls.

Consult manufacturer for voltage, current and torque rating.

*Autotransformer magnetizing current not included. Magnetizing current is usually less than 25 percent of motor full-load current.

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