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CVHE-SVX005B-EN
Figure 53.
Sequence of operation: power up to starting
Enfo rce Start to Start Timer
(5 to 60 minutes)
Prelube (60 Secon ds)
Power
Applied
to
Controls
Last Chiller Mode
Was Auto
Auto
Call for Cooling
Waiting to Start
Starting
Compressor
Wait For Oil Temp to Rise Abo ve
Sat Evap + 30F and 100F
Energize Evaporator
Water Pump Relay
Energize Condenser
Water Pump Relay
Energize Oil Pump Relay
Confirm Evaporator Water
Flow Within 4 mins 15
secon ds (6 Sec Filter)
Confirm Co ndenser Water Flow
Within 4 mins 15 second s
(6 Sec Filter)
Confirm 12 PSID Oil
Pressure
Within 3 mins
Check for High Vacuu m
Lockout
Overd rive IGV Closed
Waiting to Start
Enfo rce Stop to Start Timer Using Values From
Real Time Clock (5-200 seconds 30 is Default)
Controller
Boot
Time
(15 Sec)
Enfo rce Power Up
Start Delay T imer
(0 to 30 minutes)
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]).
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:
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 controller
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.
