Greenheck Melink IH3 Installation - Manual (Page 6)

Melink Corporation (513) 965-7300 www.melinkcorp.com
All wiring must comply with the National Electric Code (NEC
and local code requirements.
Install Variable Frequency Drive
For new construction, the Intelli-Hood includes a Variable Frequency Drive or VFD for each
kitchen exhaust and make-up air fan. This type of starter is for use with 3-phase motors only. It
not only turns the fans on and off, but also varies the speed of the motors by varying the output
frequency and voltage. Therefore, you do not need a conventional magnetic motor starter with
our system.
Caution: If you have a tempered make-up air unit, then the control circuit for the
heating system must be fed by a separate power source and NOT from the VFD! The output of
the VFD must be wired to the motor ONLY and NOT to a transformer or any part of a control cir-
cuit!
If there is a make-up air unit, then the VFD for this unit must be interlocked with the fire suppres-
sion micro-switch so that this fan turns off in the event of a fire. This is accomplished by connect-
ing a low-voltage cable between designated terminals on the VFD (01 and 04 for Allen-Bradley)
and the Normally Closed (NC) terminals on the micro-switch.
Caution: With variable frequency
drives, there must be a separate conduit run for the output of each VFD (inputs may be run to-
gether if desired). If this is not done, there is a strong probability of problems due to line interfer-
ence and inaccurate motor control.
For retrofits, the only difference between new construction and retrofits is that on retrofits you
will already have conventional magnetic motor starters installed. In most cases, it is
recommended that you install the VFD on the output side of the existing starters. This will enable
the cooks/chefs to use the existing hood fan (and light) switch and not have to change their hab-
its. This will also allow you to keep the existing circuit intact between the magnetic starter for the
make-up air unit and the fire suppression system micro-switch.
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Verify Variable Frequency Drive Wiring