16
All of the above sensors are 10,000 ohms at 77 F (25 C),
Type II thermistors and are connected to the low voltage termi-
nal (LVT). The sensor should be mounted approximately 5 ft
(1.5 m) from the floor in an area representing the average tem-
perature in the space. Allow at least 4 ft (1.2 m) between the
sensor and any corner. Mount the sensor at least 2 ft (0.6 m)
from an open doorway.
Space temperature sensor wires are to be connected to
terminals in the unit main control box. The space temperature
sensor includes a terminal block (SEN) and a RJ11 female
connector. The RJ11 connector is used for access into the Car-
rier Comfort Network
®
(CCN) at the sensor.
To connect the space temperature sensor (Fig. 10):
1. Using a 20 AWG twisted pair conductor cable rated for
the application, connect 1 wire of the twisted pair to one
SEN terminal and connect the other wire to the other
SEN terminal located under the cover of the space
temperature sensor.
2. Connect the other ends of the wires to terminals 3 and 4
on LVT located in the unit control box.
Units on the CCN can be monitored from the space at the
sensor through the RJ11 connector, if desired. To wire the RJ11
connector into the CCN (Fig. 11):
1. Cut the CCN wire and strip ends of the red (+), white
(ground), and black (–) conductors. (If another wire color
scheme is used, strip ends of appropriate wires.)
2. Insert and secure the red (+) wire to terminal 5 of the
space temperature sensor terminal block.
3. Insert and secure the white (ground) wire to terminal 4 of
the space temperature sensor.
4. Insert and secure the black (–) wire to terminal 2 of the
space temperature sensor.
5. Connect the other end of the communication bus cable to
the remainder of the CCN communication bus.
In lieu of a single sensor providing space temperature, an aver-
aging sensor array of either 4 or 9 sensors may be employed to
provide a space temperature as shown in Fig. 12. With this
control scheme, only T55 space temperature sensors (P/N
33ZCT55SPT) can be used. Total sensor wiring must not
exceed 1,000 ft (305 m).
NOTE: The Timed Override feature from a space temperature
sensor requires a single space temperature sensor connected to
the unit. This feature does not function when used with
averaging space temperature sensor arrays.
Energy Management Module (Fig. 13) — This
factory-installed option (FIOP) or field-installed accessory is
used for the following types of temperature reset, demand
limit, and/or ice features:
• 4 to 20 mA leaving fluid temperature reset (requires
field-supplied 4 to 20 mA generator)
• 4 to 20 mA cooling set point (requires field-supplied 4 to
20 mA generator)
• Discrete inputs for 2-step demand limit (requires field-
supplied dry contacts capable of handling a 24 vac,
50 mA load)
• 4 to 20 mA demand limit (requires field-supplied 4 to
20 mA generator)
• Discrete input for Ice Done switch (requires field-
supplied dry contacts capable of handling a 24 vac,
50 mA load)
See the Temperature Reset and Demand Limit sections on
pages 31 and 34 for further details.
Loss-of-Cooler Flow Protection — A proof-of-
cooler flow device is factory installed in all chillers.
Condenser Flow Protection — A proof-of-condens-
er flow protection accessory can be field installed in the con-
denser water piping of all chillers. The unit must be configured
for the input to be enabled, Configuration
OPT1
D.FL.S=ENBL.
Thermostatic Expansion Valves (TXV) — All
30MP015-045 units are equipped from the factory with con-
ventional TXVs. Two styles of TXVs are employed. The
30MPA units utilize a 15% bleed port type valve. The 30MPW
units do not require a bleed port type valve. The 30MPA units
and 30MPW units with medium temperature brine also have
factory-installed liquid line solenoids. The liquid line solenoid
valves are not intended to be a mechanical shut-off.
The TXV is set at the factory to maintain approximately 8 to
12° F (4.4 to 6.7° C) suction superheat leaving the cooler by
monitoring the proper amount of refrigerant into the cooler. All
TXVs are adjustable, but should not be adjusted unless abso-
lutely necessary.
IMPORTANT: The cable selected for the RJ11 connector
wiring MUST be identical to the CCN communication bus
wire used for the entire network. Refer to Table 10 for
acceptable wiring.
SPT (T10) PART NO. 33ZCT55SPT
SENSOR
SEN
SEN
LVT
22
23
Fig. 10 — Typical Space Temperature
Sensor Wiring
CAUTION
Care should be taken when interfacing with other manufac-
turer’s control systems due to possible power supply
differences, full wave bridge versus half wave rectification.
The two different power supplies cannot be mixed.
ComfortLink controls use half wave rectification. A signal
isolation device should be utilized if a full wave bridge sig-
nal generating device is used.
T-55 SPACE
SENSOR
CCN+
CCN GND
CCN-
TO CCN
COMM 1
BUS (PLUG)
AT UNIT
1
2
3
4
5
6
Fig. 11 — CCN Communications Bus Wiring
to Optional Space Sensor RJ11 Connector
To Next Page
Loading...
