Carrier 50HCQA - Manual (Page 29)

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Field Connections
Field connections for accessory sensors and input devices
are made the RTU--MP, at plugs J1, J2, J4, J5, J11 and J20.
All field control wiring that connects to the RTU--MP
must be routed through the raceway built into the corner
post as shown in Fig. 22. The raceway provides the UL
required clearance between high-- and low--voltage wiring.
Pass the control wires through the hole provided in the
corner post, then feed the wires thorough the raceway to
the RTU--MP. 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--MP to monitor space temperature.
There are 3 sensors available for this application:
S 33ZCT55SPT, space temperature sensor with override
button
S 33ZCT56SPT, space temperature sensor with override
button and setpoint adjustment
S 33ZCT59SPT, space temperature sensor with LCD
(liquid crystal display) screen, override button, and
setpoint adjustment
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. 31 for typical T--55 internal
connections. Connect the T--55 SEN terminals to
RTU--MP J20--1 and J20--2. See Fig. 50.
SEN
SEN
J20-1
J20-2
C08460
Fig. 50 -- RTU--MP T--55 Sensor Connections
Connect T--56: See Fig. 33 for T--56 internal connections.
Install a jumper between SEN and SET terminals as
illustrated. Connect T--56 terminals to RTU--MP J20--1,
J20--2 and J20--3 per Fig. 51.
SEN J20-1
J20-2 SEN
SET
Jumper
J20-3 SET
C08461
Fig. 51 -- RTU--MP T--56 Sensor Connections
Connect T--59: The T--59 space sensor requires a
separate, isolated power supply of 24 VAC. See Fig. 51
for internal connections at the T--59. Connect the SEN
terminal (BLU) to RTU--MP J20--1. Connect the COM
terminal (BRN) to J20--2. Connect the SET terminal (STO
or BLK) to J20--3.
OR SET SEN
OPB COM- PWR+
BLU (SPT)
BLK (STO)
24 VAC
SENSOR
WIRING
POWER
WIRING
BRN (COM)
NOTE: Must use a separate isolated transformer.
C07132
Fig. 52 -- Space Temperature Sensor Typical Wiring
(33ZCT59SPT)
Economizer Controls
Outdoor Air Enthalpy Control
(PNO 33CSENTHSW) —
The enthalpy control (33CSENTHSW) is available as a
field--installed accessory to be used with the EconoMi$er2
damper system. The outdoor air enthalpy sensor is part of
the enthalpy control. (The separate field--installed
accessory return air enthalpy sensor (33CSENTSEN) is
required for differential enthalpy control. See Fig. 36.)
Locate the enthalpy control in the economizer next to the
Actuator Motor. Locate two GRA leads in the factory
harness and connect the gray lead labeled “ESL” to the
terminal labeled “LOW”. See Fig. 36. Connect the
enthalpy control power input terminals to economizer
actuator power leads RED (connect to 24V) and BLK
(connect to GND).
The outdoor enthalpy changeover setpoint is set at the
enthalpy controller.
Differential Enthalpy Control —
Differential enthalpy control is provided by sensing and
comparing the outside air and return air enthalpy
conditions. Install the outdoor air enthalpy control as
described above. Add and install a return air enthalpy
sensor.
Return Air Enthalpy Sensor —
Mount the return--air enthalpy sensor (33CSENTSEN) in
the return--air section of the economizer. The return air
sensor is wired to the enthalpy controller
(33CSENTHSW). See Fig. 37.
50H
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