200
e. VFD maximum frequency setpoint (parameter 2008) =
motor frequency (Hz) * fan max speed (rpm) / motor
nominal operating speed (rpm). Example:
Motor Frequency = 60 Hz
Fan Max Speed = 2979 RPM
Motor Nominal Operating Speed = 1760 RPM
Max Frequency Setpoint = 60 Hz * 2979 RPM / 1760
RPM = 101 Hz
f. Using the Parameters Mode (page 153) on the VFD, ver
-
ify that parameter 2008 has been changed to the calcu
-
lated value. If it does not match, DO NOT start the unit.
Press Edit (Soft Key 2) to enter correct value for parame
-
ter 2008. Press Exit (Soft Key 1).
TWO, FOUR, OR SIX-FAN ARRAY DIRECT DRIVE PLE
-
NUM FANS
Start-up procedures for 2, 4 or 6-fan arrays are similar to those for
single direct-drive fans as described in the previous sections, with
the following additions:
1. Start-up procedures must be completed for all fans.
2. If VFD(s) is mounted on fan bulkhead panel at a shipping
split, then the VFD remote keypad assembly is shipped in
-
side the fan section. See Fig. 179.
a. Install bracket with keypad by removing an existing
screw from the cover on the vertical frame on the mating
section, taking care to avoid all door latch areas.
b. Position bracket so VFD remote keypad is upright and
attach bracket by re-installing the removed screw.
c. Plug VFD extension cable into the remote keypad and
the VFD.
d. Coil excess cable, secure with wire tie, and route cable
away from fan inlet. Secure with wire ties and screws.
3. If each motor is controlled by a single VFD, then start-up
procedures must be performed for each VFD.
4. If two or more motors are controlled by a single VFD, then
verify that both overloads in the Motor Circuit Protection
box are set to the motors’ FLA.
5. Back-draft dampers, if ordered, have been factory installed.
The back draft damper will automatically close if the fan be
-
comes disabled, thus preventing air from recirculating
through the disabled fan. Previous fan array units may have
shipped with a fan block-off plate to prevent air recirculating
through the disabled fan. The block-off plate is field installed
when a fan unit is disabled, allowing the other fan(s) to run.
The block-off plate would have shipped in the fan section. It
should have been removed and stored in a safe place for fu
-
ture use.
HUMIDIFIER INSTALLATION CHECKLIST
1. Humidifier is properly assembled with all discharge slots
facing the proper direction. (Multipipe systems have the
vertical slots in line with the manifolds, 90 degrees to the
airflow.)
2. Humidifier headers are secured and level.
3. Humidifier upright discharge manifolds are plumb.
4. Valve and trap assembly is properly assembled and con
-
nected to the humidifier header.
5. P-trap is installed on discharge of each header.
6. Steam feed line is properly run, sloped and connected to
the valve and trap assembly inlet.
7. Controls are properly wired.
HUMIDIFIER START-UP
1. Slowly open the steam isolation valve from the steam
supply line. You should be able to hear steam running
through the valve. Wait a few minutes for the steam to
heat up the entire line to the humidifier and for all con
-
densate to clear through the trap.
2. Verify that the steam trap on the valve/trap assembly of
the humidifier is working properly — condensate dis
-
charge line should be hot.
3. With air flowing in the duct or air handler, create a hu
-
midification demand by increasing the humidity control
set point until it exceeds the actual humidity reading.
4. The valve on the humidifier should begin to open and
steam should enter the humidifier manifolds.
5. Initially most of the steam will condense as it heats the
manifolds. Ensure that the P-traps on the manifolds are
clear and running to drain without leaking steam.
WHEEL OVERLAP
FAN WHEEL
BUSHING BOLTS
Fig. 178 —
Fan Wheel Bushing Location
a39-4388
EXTENSION CABLE
TO VFD
KEYPAD FROM
VFD
BRACKET
39MA51000191
FAN SECTION
BULKHEAD
FAN SECTION
FRAME
MATING SECTION
FRAME
Fig. 179 —
Remote Keypad Assembly Location
a39-4418