Protective Devices; Field-Installed Accessories - Carrier 48LC 04 Controls, Start-Up, Operation And Troubleshooting

Protective Devices

Compressor Protection
Overcurrent
Each compressor has internal line break motor protection.
Overtemperature
Each compressor has an internal protector to protect it against
excessively high discharge gas temperatures.
High- -Pressure Switch
If the high-pressure switch trips, the compressor will shut down
and the compressor safety alarm should trip. Refer to the Alarm
section for compressor safety alarms.
Evaporator Fan Motor Protection
Direct drive ECM motors are protected from locked rotor and
over-current through the electronic control module attached to the
motor. In the belt drive application, the VFD serves as the motor
thermal and over-current protection. Refer to Major Component's
section for more detail on the VFD.
CAUTION
!
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit.
DO not bypass the VFD while running the motor. Do not
change VFD parameter associated with motor characteristics,
these are factory programmed for motor protection. Damage to
the motor or the VFD can occur.
Condenser- - Fan Motor Protection
The ECM motor is protected from locked rotor and over-current
protection through the electronic control module attached to the
motor.
Saturated Suction Pressure (SSP)
If the SSP for a particular circuit is reading below the alarm set point
for an extended period of time, that circuit will be shut down. After 15
minutes, the alarm will automatically reset. If this alarm occurs 3 times
consecutively, the circuit will remain locked out until an alarm reset is
initiated via CCN or manually via the Scrolling Marquee display (see
Alarms and Alerts section for more details).
Condensate Overflow Switch (COFS)
A separate factory installed device can detect a full drain pan. This
device consists of a pan sensor to detect the water level and a relay
control switch to read the sensor. The control switch is located in
the unit control box and will trip out the compressors on overflow
detection. Since this device is in series with the compressor
contactor and high pressure switch on any given circuit,
ComfortLink does not directly read this. The relay switch is a
normally open device that closes when power is applied; this
allows the compressor to be energized without problem. If the
sensor detects high water levels for 10 seconds straight, it will open
the contact breaking the compressor call. The switch will also turn
its red LED on. If the water level is low enough for 5 minutes the
relay will close again allowing the compressor call. A blinking red
LED on the switch indicates that the sensor has been disconnected.

Field-Installed Accessories

Space Temperature Sensor (T- - 55)
The T-55 space temperature sensor (part no. 33ZCT55SPT) is a
field-installed accessory. The sensor is installed on a building
interior wall to measure room air temperature. The T-55 sensor also
includes an override button on the front cover to permit occupants
to override the Unoccupied Schedule (if programmed). The jumper
wire in the installer's packet must be connected between R and W1
when using a T-55 device.
TB - -SPT+ . . . . . . . . . Sensor Input
TB - -SPT– . . . . . . . . . . Sensor Common
Space Temperature Sensor (T- - 56)
The T-56 space temperature sensor (part no. 33ZCT56SPT) is a
field-installed accessory. This sensor includes a sliding scale on the
front cover that permits an occupant to adjust the space temperature
set point remotely. The T-56 sensor also includes an override
button on the front cover to allow occupants to override the
unoccupied schedule (if programmed). The jumper wire in the
installer's packet must be connected between R and W1 when
using a T-56 device.
TB - -SPT+ . . . . . . . Sensor Input
TB - -SPT– . . . . . . . . Sensor Common
TB - -SPTO . . . . . . . Setpoint Offset Input
Space Temperature Sensor (T- - 58)
The T-58 space temperature sensor (part no. 33ZCT58SPT) is a
field-installed accessory. The T-58 sensor communicates with the
ComfortLink controller, providing space temperature, heating and
cooling set points, and mode operation information. The jumper
wire in the installer's packet must be connected between R and W1
when using a T-58 device.
Refer to the T-58 installation instructions for information on
installing and configuring the T-58 sensor.
Each T-58 sensor must have a unique address on the CCN. Each
T-58 sensor must also be configured with the address of the unit
control it is communicating to.
Space Temperature Sensor Averaging
See Fig. 25 for space temperature averaging with T-55 sensors
only. If the use of one T-56 sensor is required, refer to Fig. 26.
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