15
Table 12 — Pressure Transducer Identification
Sensors — The electronic control uses 2 to 8 thermistors to
sense temperatures for controlling chiller operation. See
Table 7. These sensors are outlined below. Thermistors cooler
leaving fluid, cooler entering fluid, discharge temperature, cir-
cuit A return gas temperature, outdoor-air temperature sensor
or dual LWT sensor, accessory remote space temperature sen-
sor, condenser entering fluid temperature sensor, and condens-
er leaving fluid temperature sensor are identical in temperature
versus resistance and voltage drop performance. All thermis-
tors are 5,000 ohmsat 77 F (25 C) except the space tempera-
ture thermistor which is 10,000 ohms. Space temperature
thermistor (SPT) is 10,000 ohms at 77 F (25 C). See
Thermistors section on page 46 for temperature-resistance-
voltage drop characteristics.
COOLER LEAVING FLUID SENSOR (LWT) — The therm-
istor is installed in a well in the factory-installed leaving fluid
piping connecting to the bottom of the brazed-plate heat
exchanger.
COOLER ENTERING FLUID SENSOR (EWT) — The therm-
istor is installed in a well in the factory-installed entering fluid
piping connecting to the top of the brazed-plate heat exchanger.
CONDENSER LEAVING FLUID SENSOR (CDLT)
(30MPW Only) — The thermistor is installed in a well in the
field-installed leaving fluid piping connecting to the bottom of
the brazed-plate heat exchanger. The thermistor and well are a
field-installed accessory. The thermistor and well are a field-
installed accessory. See Table 13 for thermistor and well part
numbers. This sensor must be enabled, Configura-
tion
OPT1
CDWS= ENBL.
CONDENSER ENTERING FLUID SENSOR (CDET)
(30MPW Only) — The thermistor is installed in a well in the
field-installed entering fluid piping connecting to the top of the
brazed-plate heat exchanger. See Table 13 for thermistor and
well part numbers.
Table 13 — Thermistors and Wells
COMPRESSOR RETURN GAS TEMPERATURE SEN-
SOR (RGT.A) — This accessory thermistor can be installed
in a well located in the suction line. Use Carrier part number
HH79NZ029. This thermistor is standard for unit sizes 050-
071. For 015-045 this accessory must be enabled, Configura-
tion
OPT1
RG.EN = ENBL.
OUTDOOR-AIR TEMPERATURE SENSOR (OAT) —
This sensor is an accessory that is remotely mounted and used
for outdoor air temperature reset. See Table 7. Use Carrier part
number HH79NZ023. If sensor is attached, it must be enabled,
(Configuration
OPT1
OAT.E=ENBL) and include broad-
cast information.
Outside Air Temperature can be forced to a value at the
scrolling marquee or Navigator device. To force the value, ac-
cess the parameter Temperatures
UNIT
OAT. Press
to view the current value. Press again and
use the up and down arrow keys to display the desired value;
then press to accept the value. On the scrolling mar-
quee, the “.” in the lower right corner will flash. On the Navi-
gator device, a flashing “f” will be displayed next to the value.
To clear the forced value, press followed by the up
and down arrow keys simultaneously. The value will revert to
the actual reading and the flashing “.” or “f” will be removed.
DUAL LEAVING WATER TEMPERATURE SENSOR
(DLWT) — This input can be connected to the LVT. See Ta-
ble 7. For dual chiller applications (parallel only are support-
ed), connect the dual chiller leaving fluid temperature sensor
(see Table 13 for thermistor and well part numbers) to the out-
side air temperature input of the Master chiller. If outside-air
temperature is required for reset applications, connect the sen-
sor to the Slave chiller and configure the slave chiller to broad-
cast the value to the Master chiller. The broadcast must be en-
abled, (Configuration
BCST
OAT.B=ON). If there are
only two units, the master chiller must be configured to ac-
knowledge the broadcast (Configuration
BCST
BC.AK
=ON). If there are more than two units, at least one unit must
be configured to acknowledge the broadcast (Configura-
tion
BCST
BC.AK =ON).
DISCHARGE TEMPERATURE THERMISTOR
(DTT) — This sensor is only used on units with a digital
compressor. The sensor is mounted on the discharge line close
to the discharge of the digital compressor. It attaches to the dis-
charge line using a spring clip and protects the system from
high discharge gas temperature when the digital compressor is
used. This sensor is a connected to the AUX board.
SPACE TEMPERATURE SENSOR — Space temperature
sensors are used to measure the interior temperature of a
building.
Space Temperature can be forced to a value at the scrolling
marquee or Navigator device. To force the value, access the
parameter Temperatures
UNIT
SPT. Press to
view the current value. Press again and use the up
and down arrow keys to display the desired value; then press
to accept the value. On the scrolling marquee, the “.”
in the lower right corner will flash. On the Navigator device, a
flashing “f” will be displayed next to the value. To clear the
forced value, press followed by the up and down ar-
row keys simultaneously. The value will revert to the actual
reading and the flashing “.” or “f” will be removed.
The following type of SPT sensor is available:
• Space temperature sensor (33ZCT55SPT) with timed
override button (see Fig. 9)
TRANSDUCER
CARRIER
PART NUMBER
BODY
COLOR
PRESSURE
RANGE,
psi (kPa)
Discharge HK05ZZ001 Red
14.5 to 667
(100 to 4599)
Suction HK05SZ003 Yellow
–6.7 to 420
(–46 to 2896)
THERMISTOR
PART NO.
DESCRIPTION WELL PART NO.
HH79NZ014
3 in., 5,000 ohm
Thermistor
10HB50106801
HH79NZ029
4 in., 5,000 ohm
Thermistor
10HB50106802
00PPG0000B105A
1-1/2 in.,5,000 ohm
Thermistor
00PPG00000B000A
2
3
45
61
SW1
SEN
BRN (GND)
BLU (SPT)
RED(+)
WHT(GND)
BLK(-)
CCN COM
SENSOR WIRING
TIMED OVERRIDE
BUTTON (SW1)
Fig. 9 — Space Temperature Sensor
Typical Wiring (33ZCT55SPT)
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