Table of Contents
Advertisement
Field Connections
Field connections for accessory sensors and input devices
are made the RTU Open, at plugs J1, J2, J4, J5, J11 and
J20. All field control wiring that connects to the RTU
Open must be routed as shown in Fig. 28. This routing
provides the UL required clearance between high- - and
low- - voltage wiring. Connect to the wires to the
removable Phoenix connectors and then reconnect the
connectors to the board.
Space Temperature (SPT) Sensors —
A field- - supplied Carrier space temperature sensor is
required with the RTU Open to monitor space
temperature. There are 3 sensors available for this
application:
S 33ZCT55SPT, space temperature sensor with override
button (T- - 55)
S 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment (T- - 56)
S 33ZCT59SPT, space temperature sensor with LCD
(liquid crystal display) screen, override button, and
setpoint adjustment (T- - 59)
Use 20 gauge wire to connect the sensor to the controller.
The wire is suitable for distances of up to 500 ft. Use a
three- - conductor shielded cable for the sensor and setpoint
adjustment connections. If the setpoint adjustment
(slidebar) is not required, then an unshielded, 18 or 20
gauge, two- - conductor, twisted pair cable may be used.
Connect T- - 55: See Fig. 36 for typical T- - 55 internal
connections. Connect the T- - 55 SEN terminals to RTU Open
J20- - 1 and J20- - 2. See Fig. 53.
SEN
SEN
Fig. 53 - - RTU Open T- - 55 Sensor Connections
Connect T- - 56: See Fig. 38 for T- - 56 internal connections.
Install a jumper between SEN and SET terminals as
illustrated. Connect T- - 56 terminals to RTU Open J20- - 1,
J20- - 2 and J20- - 3 per Fig. 54.
SEN
SEN
Jumper
SET
SET
Fig. 54 - - RTU Open T- - 56 Sensor Connections
J20-1
J20-2
C08460
J20-1
J20-2
J20-3
C08461
Connect T- - 59: The T- - 59 space sensor requires a
separate, isolated power supply of 24 VAC. See Fig. 55
for internal connections at the T- - 59. Connect the SEN
terminal (BLU) to RTU Open J20- - 1. Connect the COM
terminal (BRN) to J20- - 2. Connect the SET terminal (STO
or BLK) to J20- - 3.
BLK (STO)
BRN (COM)
BLU (SPT)
OR
SET
SEN
OPB
COM- PWR+
NOTE: Must use a separate isolated transformer.
Fig. 55 - - Space Temperature Sensor Typical Wiring
(33ZCT59SPT)
Indoor Air Quality (CO
2
The indoor air quality sensor accessory monitors space
carbon dioxide (CO
) levels. This information is used to
2
monitor IAQ levels. Several types of sensors are available,
for wall mounting in the space or in return duct, with and
without LCD display, and in combination with space
temperature sensors. Sensors use infrared technology to
measure the levels of CO
2
The CO
sensors are all factory set for a range of 0 to
2
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO
requirements and terminal locations. See Fig. 41 for
typical CO
sensor wiring schematic.
2
To accurately monitor the quality of the air in the
conditioned air space, locate the sensor near a return- - air
grille (if present) so it senses the concentration of CO
leaving the space. The sensor should be mounted in a
location to avoid direct breath contact.
Do not mount the IAQ sensor in drafty areas such as near
supply ducts, open windows, fans, or over heat sources.
Allow at least 3 ft (0.9 m) between the sensor and any
corner. Avoid mounting the sensor where it is influenced
by the supply air; the sensor gives inaccurate readings if
the supply air is blown directly onto the sensor or if the
supply air does not have a chance to mix with the room air
before it is drawn into the return airstream.
30
J20-3
SENSOR
J20-2
WIRING
J20-1
POWER
WIRING
24 VAC
C10291
sensor) —
present in the space air.
sensor for electrical
2
2
Advertisement
Table of Contents
