CVHE-SVX005C-EN
77
Figure 53. Sequence of operation: power up to starting
Enforce Start to Start Timer
(5 to 60 minutes)
Prelube (60 Seconds)
Power
Applied
to
Controls
Last Chiller Mode
Was Auto
Auto
Call for Cooling
Waiting to Start
Starting
Compressor
Wait For Oil Temp to Rise Above
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
seconds (6 Sec Filter)
Confirm Condenser Water Flow
Within 4 mins 15 seconds
(6 Sec Filter)
Confirm 12 PSID Oil
Pressure
Within 3 mins
Check for High Vacuum
Lockout
Overdrive IGV Closed
Waiting to Start
Enforce Stop to Start Timer Using Values From
Real Time Clock (5-200 seconds 30 is Default)
Controller
Boot
Time
(15 Sec)
Enforce Power Up
Start Delay Timer
(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.
Start-Up and Shutdown
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