Controls And Compressor; Charge Refrigerant Into Chiller - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

PRESSURE TRANSDUCER CALIBRATION — Trans-
ducers measuring single pressure values (such as condenser
and evaporator pressure) are calibrated individually, while a
pair of transducers measuring a pressure differential (OIL/
PUMP DELTA P, CONDENSER WATER DELTA P,
CHILLED WATER DELTA P) are calibrated together as a dif-
ferential. In units with ICVC controllers, transducers for sens-
ing water side flow are not provided as standard. These
readings can be viewed and calibrated from the COMPRESS
and HEAT_EX screens on the ICVC controller.
Each transducer or transducer pair can be calibrated at two
points: zero (0 psig or 0 kPa) and "high end" (between 25 and
250 psig, or between 173 and 1724 kPa). It is not usually
necessary to calibrate at initial start-up. However, at high
altitude locations, recalibration may be necessary to ensure the
proper refrigerant temperature-pressure relationship.
ZERO POINT CALIBRATION — Shut down the compressor,
and cooler and condenser pumps. There must be no water flow
through the heat exchangers, but these systems must be filled.
For differential pairs, leave the transducers installed. For single
value transducers, disconnect the transducer's electrical cable,
remove the sensor from its Schrader fitting, then reconnect the
cable.
NOTE: If the cooler or condenser vessels are at 0 psig (0 kPa)
or are open to atmospheric pressure, the transducers can be
calibrated for the zero point without removal.
Access the HEAT_EX or COMPRESS screen under the
STATUS menu, and view the particular transducer reading.
(OIL PUMP DELTA P is in the COMPRESS screen; all others
are in HEAT_EX.) If the displayed reading is not 0 psi (0 kPa),
press the key to highlight the associated line in the
SELECT
display, then the key. (For zero point calibration, the
ENTER
and
INCREASE DECREASE
ue should change to 0.0.
If the ICVC fails to accept the zero point calibration, the
value will not change to 0.0 and the display will show "Higher
Force In Effect". This indicates that the sensor voltage is out of
the acceptable range. For each single value transducer there are
3 terminals at the CCM: 0 vdc (low), "sensor" voltage, and
5.00 vdc (high). With a base supply voltage of 5.00 volts, the
acceptable range of voltage taken between the low and sensor
terminals for zero point calibration is 0.40 to 0.55 v. For each
transducer differential pair there are two 3-terminal sets at the
CCM. With a base supply voltage of 5.00 volts, the acceptable
range of voltage taken between the sensor terminal for the high
end transducer (water inlet or oil pump discharge) and the
sensor terminal for the low end transducer (water outlet or oil
sump) for zero point calibration is –0.065 to +0.085 v. If this
occurs with a differential pair, one possible remedy is to swap
the high end (e.g., inlet) and low end (e.g., outlet) transducers.
In most cases this puts the sensor voltage within the acceptable
range.
HIGH END CALIBRATION — High end calibration can be
performed between 25 and 250 psig (173 and 1724 kPa),
comparing the pressure readings in the ICVC display to an
accurate refrigeration gage. While it normally will have a
negligible effect, it may improve transducer accuracy over the
full pressure range. High end calibration is not recommended
for transducer differential pairs. Pressure can be provided by
attaching a regulated 250 psig (1724 kPa) pressure source, such
as from a nitrogen cylinder, to the transducer.
Access the HEAT_EX screen under the STATUS menu,
and the CONDENSER PRESSURE or EVAPORATOR
PRESSURE to the reference pressure gage. To change the dis-
played reading, press the
SELECT
ated line in the display, then the
keys have no effect.) The val-
key to highlight the associ-
or
INCREASE DECREASE
key to set the new value, then the
value can be changed to any value within ±15% of a nominal
value.
NOTE: Prior calibrations may have shifted the present
pre-calibration value from the center of this range. In this case,
the limit of acceptable new values will be less than 15% in one
direction.
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 —
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 74 and
81, for details on the transfer of refrigerant, oil specifications,
etc.
High Altitude Locations —
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 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.
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.
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.
68
key. Generally, the
ENTER
Controls include an on/off switch,
Because the chiller is ini-