Specifications

77
TRANSDUCER REPLACEMENT — Since the transducers
are mounted on Schrader-type fittings, there is no need to re-
move refrigerant from the vessel when replacing the transduc-
ers. Disconnect the transducer wiring by pulling up on the
locking tab while pulling up on the weather-tight connecting
plug from the end of the transducer. Do not pull on the trans-
ducer wires. Unscrew the transducer from the Schrader fitting.
When installing a new transducer, do not use pipe sealer
(which can plug the sensor). Put the plug connector back on the
sensor and snap into place. Check for refrigerant leaks.
Control Algorithms Checkout Procedure —
One
of the tables on the CVC SERVICE menu is CONTROL
ALGORITHM STATUS. The maintenance screens may be
viewed from the CONTROL ALGORITHM STATUS table to
see how a particular control algorithm is operating.
These maintenance screens are very useful in helping to de-
termine how the control temperature is calculated and guide
vane positioned and for observing the reactions from load
changes, control point overrides, hot gas bypass, surge preven-
tion, etc. The tables are:
Control Test —
The Control Test feature can check all the
thermistor temperature sensors, pressure transducers, pumps
and their associated flow devices, the guide vane actuator, and
other control outputs such as hot gas bypass. The tests can help
to determine whether a switch is defective or a pump relay is
not operating, as well as other useful troubleshooting issues.
During pumpdown operations, the pumps are energized to pre-
vent freeze-up and the vessel pressures and temperatures are
displayed. The Pumpdown/Lockout feature prevents compres-
sor start-up when there is no refrigerant in the chiller or if the
vessels are isolated. The Terminate Lockout feature ends the
Pumpdown/Lockout after the pumpdown procedure is reversed
and refrigerant is added.
LEGEND TO TABLES 11A-11J
Be sure to use a back-up wrench on the Schrader fitting
whenever removing a transducer, since the Schrader fitting
may back out with the transducer, causing a large leak and
possible injury to personnel.
CAPACITY
Capacity
Control
This table shows all values used
to calculate the chilled water/
brine control point.
OVERRIDE
Override
Status
Details of all chilled water con-
trol override values.
HEAT_EX
Surge/
HGBP
Status
The surge and hot gas bypass
control algorithm status is
viewed from this screen. All
values dealing with this control
are displayed.
LL_MAINT
LEAD/LAG
Status
Indicates LEAD/LAG operation
status.
OCCDEFCM
Time
Schedules
Status
The Local and CCN occupied
schedules are displayed here to
help the operator quickly deter-
mine whether the schedule is in
the “occupied” mode or not.
WSMDEFME
Water
System
Manager
Status
The water system manager is a
CCN module that can turn on
the chiller and change the
chilled water control point. This
screen indicates the
status of this system.
CCM —
Chiller Control Module
CVC —
Chiller Visual Controller
CHW —
Chilled Water
ISM —
Integrated Starter Module
PIC II —
Product Integrated Controls II
VFD —
Variable Frequency Drive