FloAire DMUA - Manual (Page 17)

17
PSC (Permanent Split Capacitor) Motor Speed Control
Some single phase direct drive fans contain speed controls that regulate the amount
of voltage going to the motor. Specific PSC motors must be used in conjunction with
speed controls. The speed control has a knob with an off position, and high to low
range. At high speed, the speed control allows all of the line voltage to pass right to
the motor.
A minimum speed adjustment is provided to allow independent control of the
minimum speed setting. Minimum speed adjustment ensures motor runs with
sufficient torque to prevent stalling. To adjust this:
1) Motor must be in actual operating conditions to achieve proper speed adjustment. Motor will not
slow down unless proper load is applied.
2) Turn main control knob to lowest speed position.
3) Locate and adjust minimum speed setting and adjust with small screw driver. This can be found
under the speed control faceplate. (rotate clockwise to decrease minimum speed; counter-
clockwise to increase minimum speed).
4) Motor will now operate from this preset minimum speed to full speed.
The lowest minimum voltage that may be applied to these motors is 65VAC. Running lower
voltages to the motor can cause premature failure and overheating problems.
ECM (Electronically Controlled Motor) Speed Control
ECM motors and control allows accurate manual adjustment of fan speed.
The benefit of ECM motors is exceptional efficiency, performance, and
motor life.
The control used with ECM motors features a 4 digit LED numerical
display. The blue knob on the control allows the user to set the flow index
with a screwdriver. Twenty seconds later, the display shows the motor
RPM. Then, the display periodically alternates between the flow index and
motor RPM. The flow index has a range of 0 to 100% and is typically linear with motor RPM.
The ECM control requires a 24 VAC input and can locally turn the motor on and off. The motor can be
adjusted between 300 RPM and maximum speed with this control.
NOTE: To adjust the speed of 3 phase direct drive motors, a variable frequency
drive is required.
Motorized Damper
On units shipped with the optional motorized damper, power must be supplied to the damper according to
the damper nameplate. The damper motor is controlled external to the fan. External wiring to the
damper motor is required.