Icvc Operation And Menus; General - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

3.3.9 - 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
water-side 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
SATURATION TEMP reads higher than 0.6 K above the
EVAP REFRIG TRIPPOINT, and () EVAP REFRIG
TEMP (determined from the evaporator pressure sensor)
is greater than the EVAP REFRIG TRIPPOINT. If the
unit is in Pumpdown or Lockout mode, conditions (1) and
() 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 1139 kPa, and () CONDENSER PRESSURE is
less than the configured COND PRESS OVERRIDE
threshold by more than 34.5 kPa. In addition, if the water-
side 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 0.6 K
below the EVAP REFRIG TRIPPOINT, or () 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 CONDEN-
SER APPROACH exceeds the configured COND
APPROACH ALERT threshold and either (1) CONDEN-
SER PRESSURE exceeds 1139 kPa or () CONDENSER
PRESSURE exceeds the configured COND PRESS OVER-
RIDE threshold by more than 34.5 kPa. In addition, if the
water-side differential pressure measurement option is
enabled, a differential below the configured EVAP 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
determination 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 transducers may be connected to the CCM
at terminals J3 13-4 in place of the standard resistors and
jumpers to determine water-side pressure differentials as
in the standard ICVC configuration.
NOTE: If the FLOW DELTA P DISPLAY is enabled, but
the standard CCM connection is retained, a differential
value of approximately 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 CUTOUT) 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 (alarm state 9 or 30) will be declared.
If the measured differential exceeds the Flow Delta P
cutout value, flow is considered 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 4.3 kOhm resistor between CCM
terminals J3 17-18, replacing the jumper. For a condenser
side flow switch do the same between CCM terminals J3
3-4. If this type of flow switch circuit is used, it is important
to perform a zero point calibration (with the flow switch
open).
4 - ICVC OPERATION AND MENUS (FIGS. 3-9)

4.1 - 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. 3).
• 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. 4.
• The ICVC may be set to display either English or SI
units. Use the ICVC configuration screen (accessed
from the Service menu) to change the units. See the
Service Operation section, page 49.
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 authority) 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 operations, such as performing a Control
Test or accessing VFD Configuration parameters.
13