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Variable Frequency Drive
Operation
For operation with a variable frequency drive (VFD)
always check motor amps when adjusting the
operating frequency. Motor may be sized for the
original selected operating speed under 60 Hz.
Bypassing the VFD or increasing the speed from this
original selection, even if less than 60 Hz, may cause
motor to overload or fail. Consult factory with fan
serial number before increasing the upper limiting
frequency.
Always check the fan RPM when adjusting the
operating frequency. Do not exceed maximum class
fan RPM of the wheel.
NOTE
It is the responsibility of the installing body to
perform coast-down tests and identify any resonant
frequencies after the equipment is fully installed.
These resonant frequencies are to be removed
from the operating range of the fan by using the
"skip frequency" function in the VFD programming.
Failure to remove resonant frequencies from the
operating range will decrease the operating life of
the fan and void the warranty.
Model USFD - Variable Speed Drives
The USFD-100 comes equipped with a factory
integrated speed controller. Single-phase models will
®
use a Vari-Green
Motor and Potentiometer dial to
adjust motor rpm. To change the speed, simply turn
the dial. Three-phase models will offer a mounted,
wired and programmed VFD and premium induction
motor. Changing speeds on a 3-phase model involves
pressing the up and down arrows located on the VFD
interface (see section under Unit Start-Up).
Both single- and three-phase versions feature a built-
in electrical disconnect and the option for external
control through 0-10 VDC signal.
For additional information on the USFD-100 variable
speed controls:
Single-phase - see IOM #473681 - Vari-Green Motor
and Controls at www.greenheck.com under Library
and Literature.
Three-phase - Download the Yaskawa Manual for AC
Drive - J1000 at www.yaskawa.com.
18
Utility and Centrifugal Fans
®
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