Ericsson RBS 2106 Hardware Reference Manual page 299

Combined Climate Unit
The outside air circulates through one side of the heat exchanger and the
inside air circulates through the other side. DC-powered fans force the air
through the heat exchanger. The inside air is cooled by the outside air.
4.2 Active Cooler
This unit consists of a compressor, reducing valve, condenser, evaporator and
an AC-powered condenser fan.
The liquid coolant passes through a reducing valve, where it evaporates to a
cold low-pressure gas. This gas flows through the evaporator and cools it. The
inside air that has passed the heat exchanger is blown through the evaporator,
cooled and returned to the cabinet subracks.
The compressor compresses the coolant to a liquid state again in the
condenser. The coolant and the condenser become hot in the process. An
AC-powered fan circulates the outside air through the condenser and cools it.
When the temperature exceeds the compressor start point, the CCU supplies
mains voltage, first to the condenser fan and then to the compressor. The
condenser fan runs when the compressor is running and one minute after the
compressor is switched off. The compressor cannot start again before the
condenser fan has stopped. This is done to equalise the pressure differences
in the cooling system before the compressor starts.
When the temperature decreases below the compressor stop value, a
compressor stop signal is activated, but the compressor will continue running
for at least 10 minutes.
If the mains current to the compressor is missing, it is reported as compressor
failure.
The condenser fan is provided with a rotation signal output. If the signal is
missing, an active cooler fan alarm is reported.
4.3 Heater
The heater is placed in the internal air circuit and heats the air if the ambient
temperature is too low for start up.
The heater is powered by mains voltage, and heats the inside air if the start-up
temperature inside the cabinet is below +5° C. The heater has a capacity of
2 kW.
The CCU measures the return air temperature and controls the heater.
4.4 Climate Control Unit
The Climate Control Unit (CCU) is a processor based plug-in unit, that controls
and supervises the climate unit. It has a set of default operating parameters,
which can be overridden by loaded parameters. The backplane connectors
EN/LZT 720 0239 R1B
Climate Unit for RBS 2106
5 (8)