Thermistors; Connections At Customer's Terminal Block; Fault Reporting On Circuits A And B; Evaporator Pump Contactor Control - Carrier 30GX Installation, Operation And Maintenance Instructions

Economizer pressure sensors
These sensors are used to measure the intermediate pressure
between high and low pressure. They are used to control the oil
pressure differential. They are located on the suction line of the
economiser circuit (for units equipped with economizers) or on
the cooling line of each motor.

3.3.7 - Thermistors

These all have similar characteristics.
Evaporator entering and leaving water temperature sensor
The evaporator entering water temperature sensor and the
leaving water temperature sensor are installed in the entering
and leaving side water box.
Discharge gas sensor
This sensor is used to measure the discharge gas temperature,
and permits control of the discharge temperature superheat. It
is located in the discharge line of each circuit (oiler entering or
leaving line, depending on the model).
Motor sensor
This is used to control the motor temperature of each
compressor. The terminals of this sensor are situated on the
compressor terminal board.
Evaporator liquid level sensor
This is used to measure the refrigerant charging level. It
ensures optimised flow control in the evaporator, and is
installed at the top of the evaporator.
Condenser entering and leaving water temperature sensors
These are used to control the heating capacity on heat pumps.
In cooling only units they have no control function. They are
installed in the common condenser entering and leaving line.
Heat reclaim condenser entering/leaving water
temperatures
These sensors measure the entering and leaving water
temperatures of heat reclaim condensers and are used on air-
cooled units. They may be fitted as options.
Temperature setpoint reset sensor
This is an optional 0-10 V sensor which can be installed
remotely from the unit. It is used to reset the cooling and
heating setpoint on the unit as a function of either the outdoor
air temperature or ambient room temperature. The sensor is not
supplied by Carrier. Its characteristics must be configured by
Carrier Service. See section 3.4.10 for connection instructions.
8

3.4 - Connections at customer's terminal block

The connections below are available at the customer's terminal
block. Some of them can only be used in special operating
modes. For further details see the sections that describe the
functions (section 5) and the configurations (section 4.2.10).
NOTE: The bridge between terminals 32, 63 and 65 on the
customer's terminal block must not be removed.

3.4.1 - Fault reporting on circuits A and B

These are live contacts. They must be supplied with 24 V a.c.
and maximum current 0.5 A*.
Fig. 3 - Fault report alarm connections
24 V a.c. supply
Alarm
ALARM
NOTE: To obtain a volt-free dry alarm contact, these outputs
must be interfaced with a relay supplied with 24 V a.c. (Carrier
Part No. —OK—12AC-034—EE).

3.4.2 - Evaporator pump contactor control

The evaporator pump contactor can be supplied with 24 V a.c.
and a maximum current of 0.5 A* between terminals 12 and
90.
Fig. 4 - Evaporator pump connections

3.4.3 - Condenser pump contactor control

The condenser pump contactor can be supplied with 24 V a.c.
and a maximum current of 0.5 A* between terminals 95 and 12.
Fig. 5 - Condenser pump connections
24 V a.c. supply
ALARM Alarm
Con-
tactor
Pump
Con-
tactor
Pump