Daikin Rebel Applied DPSA - Fixed Speed Compressor Start-up; Scroll Compressor Rotational Direction

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www.DaikinApplied.com 79 IM 1287-6 • REBEL APPLIED ROOFTOP
Fixed Speed Compressor Start-up
CAUTION
Low ambient temperature can cause compressor damage. Do not attempt
to start up and check the refrigeration system when the outdoor air
temperature is below 50°F unless the unit is specially equipped for low
ambient operation.
NOTICE
Venting refrigerant to atmosphere is not allowed per federal and state laws
and local regulations and codes.
Make certain the supply and return fans are operational and
prepare for compressor operation.
If the unit contains optional compressor isolation valves, Verify
that valves are open. These are ball valves that can be opened
with a quarter turn.
Verify that the unit has not lost its refrigerant charge. Check the
compressor oil level before start-up. The oil level should be at
or slightly above the center of the sight glass.
Verify that the crankcase heaters are energized. These should
operate for at least 24 hours before starting the compressors.
Verify that the condenser fan blades are positioned properly
and that the screws are tight (Figure 150). The fan blade
must be correctly positioned within its orice for proper airow
across the condenser coils.
Figure 150: Condenser Fan Blade Positioning
Scroll Compressor Rotational Direction
Scroll compressors only compress in one rotational direction.
Three-phase compressors can rotate in either direction
depending upon phasing of the power to L1, L2, and L3.
Since there is a 50/50 chance of connecting power to cause
rotation in the reverse direction. Use a phase rotation meter
to conrm phasing is clockwise. If the compressor is rotating
properly when energized, the suction pressure will decrease
and the discharge pressure will increase. If the compressor is
rotating in reverse, the sound level is louder and current draw
is reduced substantially. After several minutes of operation
rotating in the incorrect direction, the compressor’s motor
protector may trip. Tripping will not damage the compressor as
long as it does not continue to repeat this cycle.
All three-phase compressors are wired the same internally.
Therefore, once the correct phasing is determined for a specic
system or installation, connecting properly phased power
leads to the same terminals should maintain proper rotational
direction.
Perform the following procedure on all units:
1. At the keypad, The cooling set point value in Commission
Unit\Cooling Set-Up\Occ Clg Spt will need to be adjusted
below the Control Temp shown in the same menu. In
addition, on DAC units, adjust the value in Commission
Unit\CoolingSet-Up\DAT Clg Spt below the temperature
shown in Disch Air in the same menu.
2. Place the unit into cooling mode through the keypad
menu Quick Menu\Ctrl Mode = Cool Only.
3. Verify that the low ambient compressor lockout
temperature setpoint, Main Menu\Commission Unit\
Cooling Setup\Clg Lo OAT Lk is set below the current
outside air temperature (OA Temp) is shown in the same
menu.
NOTE: Do not attempt to operate the compressors if the
outdoor air is below 50°F. See the caution statement
under “Fixed Speed Compressor Start-up”.
4. Note that if the unit has an economizer and the outdoor
air enthalpy is low, the economizer must fully open
before the controller will energize mechanical cooling.
5. When the outdoor air damper has fully opened and the
time delay has expired, the liquid line solenoid and the
compressor should start.
a. Verify that there is a call for cooling by checking
the keypad menu Quick Menu\Unit State =. This
should be in Cooling.
b. Check the keypad to ensure the compressors have
been enabled. Main Menu\ViewStatus\Unit Status/
Settings\Clg Status =. The compressors will only
run if this reads (Enabled).
6. Verify that compressor #1 starts. If the compressor motor
hums but does not run, verify that it is getting three-
phase power.
1.25"