Brochure

© 1998 Square D All Rights Reserved
40
5/98
Multispeed motors are available in two basic versions:
• Consequent pole
• Separate winding
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 to the left.
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.
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 consequent pole and separate winding motors are available in three types:
• Constant horsepower
• Constant torque
• Variable torque
Typical applications for these different types of motors are shown below.
NOTE: For detailed information involving the technical aspects of flexibility of
the starters used in the multispeed controllers, see Classes 8702, 8736 and
8810 application data.
Typical Applications
Constant H.P.
• Spindles
• Cutting Tools
— Lathes
—Saws
Constant Torque
• Conveyors
• Mills
• Dough Mixers
• Reciprocating Pumps
Variable Torque
• Fans
• Centrifugal Pumps
Speed Selection
The speed of a squirrel cage motor is directly proportional to the power
supply frequency and inversely proportional to the number of poles in the
stator winding. With the frequency constant, motor speed is determined by
the number of poles.
(RPM) Speed =
(120) (Frequency)
No. of Poles
Horsepower =
T x S Where:
T = Torque in Lb Ft
S = Speed in RPM
5250
Typical Schematic Diagrams
AC Multispeed Magnetic Starters
Application Data – Class 8810, 8811, 8812
2-Speed Consequent Pole Constant Horsepower
NEMA Size 0-4
Sizes 5, 6 & 7 Use Special Circuitry
2-Speed Consequent Pole Constant or Variable Torque
NEMA Size 0-4
Sizes 5, 6 & 7 Use Special Circuitry
2-Speed Separate Winding Constant HP, Constant Torque
and Variable Torque NEMA Size 0-4
Sizes 5, 6 & 7 Use Special Circuitry
Stop
High
4
Low
5
H
High
L
2
H
3
L
LL
LLL
L1
L2
L3
L
OL OL
H
H
HH
OL OL OL OL OL OL
T1 T2 T3 T6 T4 T5
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A30064-446
Stop
High
4
Low
5
H
High
L
2
H
3
L
LLL
L1
L2
L3
L
OL OL
H
H
HH
HH
OL OL OL OL OL OL
T1 T2 T3 T6 T4 T5
1
Stop
High
4
Low
5
H
High
L
2
H
3
L
LLL
L1
L2
L3
L
OL OL
H
H
HH
OL OL OL OL OL OL
T1 T2 T3 T11 T12 T13
A30064-442
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