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S S t t a a r r t t - - u u p p a a n n d d S S h h u u t t - - d d o o w w n n
Figure 58. Sequence of operation: power up to starting
Power
Applied
to
Controls
UC800
Boot Time
(30 to 50
seconds)
Now that the compressor motor is running in the
"Delta" configuration, the inlet guide vanes will
modulate, opening and closing to the chiller load
variation by operation of the stepper vane motor
actuator to satisfy chilled water setpoint. The chiller
continues to run in its appropriate mode of operation:
Normal, Softload, Limit Mode, and so on (refer to the
following figure [running]).
N N o o t t e e : : For more information, refer to
Compressor Sequencing," p.
If the chilled water temperature drops below the chilled
water setpoint by an amount set as the differential to
stop setpoint, a normal chiller stop sequence is
initiated as follows:
76
Last Chiller Mode
Was Auto
Call for Cooling
Auto
Waiting to Start
Wait for Highest Motor Winding
Temp to Fall Below 165°F (73.9°C)
Enforce Power Up
Wait for Oil Temp to Rise Above
Start Delay Timer
Sat Evap + 30°F (16.7°C)
(0 to 30 minutes)
and 100°F (37.8°C)
Energize Evaporator
Water Pump Relay
Confirm Evaporator Water
Flow Within 4 min 15 sec
(6 second Filter)
Enforce Stop to Start Timer Using Values from
Real Time Clock (5 to 200 seconds; 30 is default)
"Duplex
68.
Waiting to Start
Prelube (60 seconds)
Overdrive IGV Closed
Energize Condenser
Water Pump Relay
Confirm Condenser Water Flow
Within 4 min 15 sec
(6 second Filter)
Energize Oil Pump Relay
Confirm 12 psid (82.7 kPaD)
Oil Pressure
Within 3 minutes
Check for High Vacuum
Lockout
1. The inlet guide vanes are driven closed (up to
50 seconds).
2. After the inlet guide vanes are closed, the stop relay
and the condenser water pump relays open to turn
off. The oil and refrigerant pump motor will
continue to run for 3 minutes post-lube while the
compressor coasts to a stop. The chilled water
pump will continue to run while the UC800
monitors leaving chilled water temperature,
preparing for the next compressor motor start
based on the differential to start setpoint.
The following figure (satisfied setpoint) illustrates this
sequence.
Starting
Compressor
CDHF-SVX01N-EN
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