Carrier 30GK The evaporator pumps, The condenser pump, Pressure sensors, Oil pressure sensors

3.3.3 - The evaporator pumps

The controller can regulate one or two evaporator pumps, with automatic changeover between the two pumps.

3.3.4 - The condenser pump

In appropriate cases the controller can regulate a condenser pump (for water-cooled units or air-cooled units with heat reclaim option). This control does not require an additional board.

3.3.5 - Pressure sensors

These are used to measure the following pressures in each circuit:

•Discharge gas pressure (high pressure type)

•Suction pressure (low pressure type)

•Oil pressure (option)

These electronic sensors deliver 0 to 5 V d.c. to the main board or to a 4xAI-2xAO slave board. Two sensor versions are used; one is calibrated for high pressure and the other for low pressure and oil pressure.

Discharge pressure sensors

These are on the high pressure side of the lead compressor in each circuit. They replace the usual discharge gas pressure gauges and can be used to control head pressure or by the high pressure load shedding option.

Oil pressure sensors

If installed, these sensors are used to measure the compressor oil pressure on the oil pressure discharge side. The suction pressure is subtracted from the oil pressure value to arrive at the differential oil pressure.

Suction pressure sensors

They are located in the low-pressure side of the unit on the lead compressor of each circuit. The suction pressure sensor reading is used to control the electronic expansion devices EXV. They permit replacement of the low-pressure switches, low-pressure gauges and possibly of the oil pressure safety switch.

3.3.6 - Thermistors

These all have similar characteristics.

Evaporator entering water temperature sensor

The evaporator entering water temperature sensor is installed in the evaporator wall in the free space at the side of the tube bundle.

Evaporator leaving water temperature sensor

The evaporator leaving water temperature sensor is installed in evaporator leaving water piping: The sensor bulb is directly immersed in the water.

Compressor suction sensor

This is located in the lead compressor of each circuit in the suction gas line situated between the motor and the cylinders above the oil pump.

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 tempera- tures of heat reclaim condensers and are used on air-cooled units equipped with the heat reclaim option. If not, they may be fitted as options. In this case they only have informative character.

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, and must be configured by the User Menu.

Outdoor temperature sensor

Mounted on the control box. It is used for start-up, setpoint temperature reset and frost protection control.

Master/slave assembly temperature control

The optional water temperature sensor can be used for master/ slave assembly control.

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