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M
M-4
CONTROLLERS, VSD, SENSORS & RUN-ON TIMERS
CONTROLLERS, VSD, SENSORS & RUN-ON TIMERS
© FANTECH
2016
MULTI-SPEED MOTORS
These can be either tap (Dahlander) or dual-wound.
Tap-wound motors use a single set of windings with a control ‘tap’ in each coil.
The speed ratio is 2:1 and the maximum speed can be any synchronous speed. i.e 48,
24, 16, 12, rev/sec etc.
Dual-wound motors are effectively two motors in one as there are two separate sets
of windings in the one motor frame. With dual-wound motors almost any combination
of standard motor speeds is possible.
Multi-speed motors provide excellent power saving and the noise reduction is the
same as any other fan with the same speed difference.
The air capacities available are directly proportional to the speeds.
Although by no means exclusive the above methods are more frequently applied to
standard motors.
Note: Multi-speed motors are typically larger than their single speed equivalents.
GENERAL
If you have requirements not detailed here, contact our Sales Engineers for assistance,
as not all control devices have been covered in this catalogue.
SUMMARY OF AIR CAPACITY CONTROL OPTIONS
Control Type
Speed Ratio
Approx. Power
Savings
Relative Cost
Star/delta switch 1.3:1
50%
low
Star/delta controller 1.3:1
50%
moderate
Triac
10:1
to 70%
low
Capacitance
Down to 2:1
varies
low/moderate
Frequency inverter
5:1
to 90%
highest
Tap winding
2:1
87%
low/moderate
Dual-wound
3:2
70%
low/moderate