Frequently asked questions

FA99356

19 July 2022

Issue:
Difference between a two types of two-speed starters

Product Line:
8810 Multispeed Magnetic Starters

Environment:
NEMA Starters and Contactors 

Cause:
Selecting a two speed starter

Resolution:
Multispeed motors are available in two basic versions:
1) separate winding and 2) consequent pole.
A separate winding motor has a winding for each speed while a consequent pole motor has a winding for every two speeds (three-speed motors have two windings).
The motor connections (and thus the types of controllers) for two speed starters are exemplified by the schematic diagrams shown in Table 16.22. Note that consequent pole two-speed controllers involve a 5-pole and a 3-pole starter, while separate winding controllers have two 3-pole starters.
Verify the type of motor before ordering. Field modification of starters to match the motor may not be possible.
Separate winding motors are usually chosen when flexibility is important, since the speeds of a consequent pole motor are usually limited to a 2/1 ratio; a broad range of speeds can be obtained on a separate winding motor.
Both separate winding and consequent pole motors are available in three types:
1) constant horsepower, 2) constant torque, and 3) variable torque.