Trane CenTraVac Duplex CDHE, Operation & Maintenance Manual

Page: 69 / 116

69
CDHF-SVU01C-EN
Now that the compressor motor
(4M1) 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 (4M2) 4M4 (extended
capacity) to satisfy chilled water
setpoint. The chiller continues to run
in its appropriate mode of operation:
Normal, Softload, Limit Mode,
etcetera. As explained in the General
Information section.
If the chilled water temperature drops
below the chilled water set point by
an amount set as the ‘‘differential to
stop’’ setpoint, a normal chiller stop
sequence is initiated as follows:
(Refer to Figure 10.)
1. The inlet guide vanes are driven
closed for 50 seconds.
2. After the 50 seconds has elapsed,
the stop relay (2A1-J10) and the
condenser water pump relays (1A5-
J2) open to turn off. The oil and
refrigerant pump motor (4B3) 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 Main
processor module (1A22) monitors
leaving chilled water temperature
preparing for the next compressor
motor start based on the
‘‘differential to start’’ setpoint.
If the STOP key is pressed on the
operator interface, the chiller will
follow the same stop sequence as
above except the chilled water pump
relay (1A5-J2) will also open and stop
the chilled water pump after the
chilled water pump delay timer has
timed out after compressor shut
down.
If the “Immediate Stop” is initiated, a
panic stop occurs which follows the
same stop sequence as pressing the
STOP key once except the inlet guide
vanes are not sequence closed and
the compressor motor is immediately
turned off.
Control Sequence
of Operation