Flow Detection; Icvc Operation And Menus; General; Alarms And Alerts - Carrier AquaEdge 19XRV series Operation, Maintenance And Installation Manual

A Refrigerant Saturation Temperature sensor (thermistor) is
located in the base of the evaporator, sensing refrigerant
temperature directly. Evaporator and condenser water side
differential pressure transducers are not standard and are not
required. The ICVC software uses the evaporator saturation
refrigerant temperature in place of differential pressure flow
detection to provide evaporator freeze protection.
Approach temperatures are shown in the HEAT_EX screen.
EVAPORATOR APPROACH is defined as LEAVING
CHILLED WATER temperature minus EVAP SATURATION
TEMP (from the temperature sensor). CONDENSER AP-
PROACH is defined as CONDENSER REFRIG TEMP (de-
rived from condenser pressure) minus LEAVING CONDENS-
ER WATER temperature. When chiller is running, the displayed
value for either approach will not be less than 0.2 F (0.1 C). If
either approach value exceeds the value configured in the SET-
UP1 screen, the corresponding Approach Alert message will
be entered into the Alert History table.
FLOW DETECTION — Flow detection for the evaporator
and condenser is a required condition for start-up and used in
the freeze protection safety. Flow and no flow conditions are
detected from a combination of several measurements. The
usage of waterside differential pressure measurements is not
standard or required.
Positive determination of flow on the evaporator side is
made if the following conditions are true: (1) the EVAP SATU-
RATION TEMP reads equal to or higher than 1° F (0.6 C)
above the EVAP REFRIG TRIPPOINT, and (2) EVAP RE-
FRIG TEMP (determined from the Evaporator Pressure sen-
sor) is greater than the EVAP REFRIG TRIPPOINT plus 1° F.
(If the unit is in Pumpdown or Lockout mode, conditions (1)
and (2) are not required to establish flow.) On the condenser
side, positive determination of flow is made if the following
conditions are true: (1) the CONDENSER PRESSURE is less
than 165 psig (1139 kPa), and (2) CONDENSER PRESSURE
is less than the configured COND PRESS OVERRIDE thresh-
old by more than 5 psi (34.5 kPa). In addition, if the waterside
differential pressure measurement option is enabled, the water-
side pressure differentials (cooler and condenser) must exceed
their respective configured cutout thresholds.
A No Flow determination is made on the evaporator side if
(1) the EVAP SATURATION TEMP reads lower than 1° F
(0.6 C) below the EVAP REFRIG TRIPPOINT, or (2) EVAP
REFRIG TEMP (determined from the Evaporator Pressure
sensor) is less than the EVAP REFRIG TRIPPOINT and the
EVAPORATOR APPROACH exceeds the configured EVAP
APPROACH ALERT threshold. On the condenser side, a No
Flow determination is also made if the CONDENSER AP-
PROACH exceeds the configured COND APPROACH ALERT
threshold and either (1) CONDENSER PRESSURE exceeds
165 psig (1139 kPa) or (2) CONDENSER PRESSURE exceeds
the configured COND PRESS OVERRIDE threshold by more
than 5 psi (34.5 kPa). In addition, if the water-side differential
pressure measurement option is enabled, a differential below
the configured EVAP FLOW DELTA P CUTOUT or COND
FLOW DELTA P CUTOUT value is sufficient to establish No
Flow in either heat exchanger.
If No Flow (for either cooler or condenser) has been deter-
mined, and subsequently conditions change such that neither
conditions for Flow nor No Flow are all satisfied, the determi-
nation will remain No Flow.
In the standard ICVC setup, water-side differential pressure
indication is disabled by default. The displays for CHILLED
WATER DELTA P and CONDENSER WATER DELTA P in the
HEAT_EX screen will show "*****". In order to enable the
option and display a value, change FLOW DELTA P DISPLAY
to ENABLE in the SETUP1 screen. Pairs of pressure transduc-
ers may be connected to the CCM at terminals J3 13-24 in
place of the standard resistors and jumpers to determine wa-
ter-side pressure differentials as in the standard ICVC
configuration. (NOTE: If the FLOW DELTA P DISPLAY is en-
abled, but the standard CCM connection is retained, a differen-
tial value of approximately 28.5 psi (197 kPa) will always be
displayed.)
If water-side differential pressure transducers are used, flow
is detected from differential pressure between sensors (pressure
transducers) located in water inlet and outlet nozzles, for each
heat exchanger. The thresholds for flow determination (EVAP
FLOW DELTA P CUTOUT, COND FLOW DELTA P CUT-
OUT) are configured in the SETUP1 screen. If the measured
differential is less than the corresponding cutout value for
5 seconds, the determination is that flow is absent. If no flow is
detected after WATER FLOW VERIFY TIME (configured in
the SETUP1 screen) after the pump is commanded to start by
the PIC, a shutdown will result, and the corresponding loss-of-
flow alarm state 229 or 230) will be declared. If the measured
differential exceeds the Flow Delta P cutout value, flow is con-
sidered to be present.
Alternatively, normally open flow switches may be used for
flow indication. In this case, install an evaporator side flow
switch in parallel with a 4300-ohm resistor between CCM
terminals J3 17-18, replacing the jumper. See page 146. For a
condenser side flow switch do the same between CCM termi-
nals J3 23-24. If this type of flow switch circuit is used, it is
important to perform a zero point calibration (with the flow
switch open).
ICVC Operation and Menus (Fig. 18-24)

GENERAL

• The ICVC display automatically reverts to the default
screen after 15 minutes if no softkey activity takes place and
if the chiller is not in the pump down mode (Fig. 18).
• If a screen other than the default screen is displayed on the
ICVC, the name of that screen is in the top line. See Fig. 19.
• The ICVC may be set to display either English or SI units.
Use the ICVC configuration screen (accessed from the Ser-
vice menu) to change the units. See the Service Operation
section, page 60.
NOTE: The date format on the default screen is MM-DD-YY
for English units and DD-MM-YY for SI metric units.
• Local Operation — In LOCAL mode, the PIC III accepts
commands from the ICVC only and uses the local time
occupancy schedule to determine chiller start and stop
times. The PIC III can be placed in the local operating mode
by pressing the LOCAL softkey. When RUN STATUS is
READY, the chiller will attempt to start up.
• CCN Operation — In CCN mode, the PIC III accepts input
from any CCN interface or module (with the proper author-
ity) as well as from the local ICVC. The PIC III uses the
CCN time occupancy schedule to determine start and stop
times. The PIC III can be placed in the local operating mode
by pressing the CCN softkey. When RUN STATUS is
READY, the chiller will attempt to start up.
• OFF — The control is in OFF mode when neither the
LOCAL nor CCN softkey cue is highlighted. Pressing the
STOP key or an alarm will place the control in this mode.
The PIC III control must be in this mode for certain opera-
tions, such as performing a Control Test or accessing VFD
Configuration parameters.
ALARMS AND ALERTS — An alarm shuts down the com-
pressor. An alert does not shut down the compressor, but it
notifies the operator that an unusual condition has occurred. An
alarm (*) or alert (!) is indicated on the STATUS screens on the
far right field of the ICVC display screen.
Alarms are indicated when the ICVC alarm light (!) flashes.
The primary alarm message is displayed on the default screen.
An additional, secondary message and troubleshooting infor-
mation are sent to the ALARM HISTORY table.
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