Carrier XRV Especificaciones descargar pdf (Pagina 19)

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

(derived from condenser pressure) minus LEAVING CON-

DENSER 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 SETUP1 screen, the corresponding Approach Alert mes-

sage 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 higher than 1° F (0.6 C) above the

EVAP REFRIG TRIPPOINT, and (2) EVAP REFRIG TEMP

(determined from the Evaporator Pressure sensor) is greater

than the EVAP REFRIG TRIPPOINT. (If the unit is in Pump-

down or Lockout mode, conditions (1) and (2) are not required

to establish flow.) On the condenser side, positive determina-

tion 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 threshold by more than 5 psi

(34.5 kPa). In addition, if the waterside differential pressure

measurement option is enabled, the waterside pressure differ-

entials (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

APPROACH exceeds the configured COND APPROACH

ALERT threshold and either (1) CONDENSER PRESSURE

exceeds 165 psig (1139 kPa) or (2) CONDENSER PRES-

SURE 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 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, waterside 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 pres-

sure transducers may be connected to the CCM at terminals

J3 13-24 in place of the standard resistors and jumpers to deter-

mine 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 differ-

ential value of approximately 28.5 psi (197 kPa) will always be

displayed.)

If waterside 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 (alarm state 229 or 230) 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 4.3k ohm resistor between CCM

terminals J3 17-18, replacing the jumper. See page 136. 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. 14-20)

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. 14).

• 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. 15.

• 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 56.

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.

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 189 190

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