Carrier XRV Especificações descarregar pdf (Página 74)

If the ICVC fails to accept the high end calibration, the

value will not change and the display will show “Higher Force

In Effect.” This indicates that the sensor voltage is out of the

acceptable range for the entered value. If this occurs with a

differential pair, one possible remedy is to swap the high end

(inlet) and low end (outlet) transducers. In most cases this puts

the sensor voltage within the acceptable range.

Each transducer is supplied with 5 vdc power from the

CCM. Pressure transducer readings are derived from voltage

ratio, not absolute voltage, which compensates for any

reference voltage variation. If this power supply fails, a

transducer voltage reference alarm is generated. If transducer

readings are suspected of being faulty, check the supply

voltage, measured between the high and low (first and third)

terminals of any transducer 3 terminal connection at the CCM.

This is also displayed in CONTROL TEST under CCM

PRESSURE TRANSDUCERS.

Check Optional Pumpout System Controls

and Compressor —

Controls include an on/off switch,

a 0.5-amp fuse, the compressor overloads, an internal thermo-

stat, a compressor contactor, refrigerant low pressure cut-out,

and a refrigerant high pressure cutout. The high pressure cutout

is factory set to open at 185 psig (1276 kPa) and reset at

140 psig (965 kPa). The low pressure cutout is factory set to

open at 7 psia (–15.7 in. HG) and close at 9 psia (–11.6 in. HG).

Ensure the water-cooled condenser has been connected. Ensure

oil is visible in the compressor sight glass. Add oil if necessary.

See the Pumpout and Refrigerant Transfer Procedures and

Optional Pumpout System Maintenance sections, pages 81 and

88, for details on the transfer of refrigerant, oil specifications,

etc.

High Altitude Locations — Because the chiller is ini-

tially calibrated at sea level, it is necessary to recalibrate the

pressure transducers if the chiller has been moved to a high

altitude location. See the calibration procedure in the Trouble-

shooting Guide section.

Charge Refrigerant into Chiller

The standard 19XRV chiller is shipped with the refrigerant

already charged in the vessels. However, the 19XRV chiller

may be ordered with a nitrogen holding charge of 15 psig

(103 kPa). Evacuate the nitrogen from the entire chiller, and

charge the chiller from refrigerant cylinders.

CHILLER EQUALIZATION WITHOUT A PUMPOUT

UNIT

To equalize the pressure differential on a 19XRV chiller

with the refrigerant isolated in one of the heat exchangers, use

the terminate lockout function of the CONTROL TEST on the

SERVICE menu. This helps to turn on pumps and advises the

operator on proper procedures.

The following steps describe how to equalize refrigerant

pressure in an isolated 19XRV chiller without a pumpout unit.

1. Access terminate lockout function on the CONTROL

TEST screen.

3. Slowly open the motor cooling isolation valve. The

chiller’s cooler and condenser pressures will gradually

equalize. This process takes approximately 15 minutes.

4. Once the pressures have equalized, the cooler isolation

valve, the condenser isolation valve, and the hot gas isola-

tion valve may now be opened. Refer to Fig. 30 and 31,

for the location of the valves.

CHILLER EQUALIZATION WITH PUMPOUT UNIT —

The following steps describe how to equalize refrigerant

pressure on an isolated 19XRV chiller using the pumpout unit.

1. Access the terminate lockout function on the CONTROL

TEST screen.

3. Open valve 4 on the pumpout unit and open valves 1a and

1b on the chiller cooler and condenser, Fig. 30 and 31.

Slowly open valve 2 on the pumpout unit to equalize the

pressure. This process takes approximately 15 minutes.

4. Once the pressures have equalized, the discharge isola-

tion valve, cooler isolation valve, optional hot gas bypass

isolation valve, and the refrigerant isolation valve can be

opened. Close valves 1a and 1b, and all pumpout unit

valves.

The full refrigerant charge on the 19XRV chiller will vary

with chiller components and design conditions, as indicated on

the job data specifications. An approximate charge may be de-

termined by adding the condenser charge to the cooler charge

as listed in Table 14A and 14B.

CAUTION

The transfer, addition, or removal of refrigerant in spring

isolated chillers may place severe stress on external piping

if springs have not been blocked in both up and down

directions. Failure to block springs in both up and down

directions could result in severe personal injury and equip-

ment damage.

CAUTION

Always operate the condenser and chilled water pumps

during charging operations to prevent freeze-ups. Damage

could result to equipment if condenser and chilled water

pumps are not operated during pumpdown or charging.

CAUTION

When equalizing refrigerant pressure in the 19XRV chiller

after service work or during the initial chiller start-up, do

not use the discharge isolation valve to equalize. Either the

motor cooling isolation valve or a charging hose (con-

nected between the refrigerant charging valves on top of

the cooler and condenser) should be used as the equaliza-

tion valve. Damage to the float valve could result.

WARNING

Whenever turning the discharge isolation valve, be sure to

reattach the valve locking device. This prevents the valve

from opening or closing during service work or during

chiller operation, which could result in serious personal

injury.

IMPORTANT: Turn on the chilled water and con-

denser water pumps to prevent freezing.

IMPORTANT: Turn on the chilled water and con-

denser water pumps to prevent freezing.

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