3 Device description
EN
18 Rittal enclosure cooling unit
Fig. 3: Cooling circuit
In the evaporator coil (1), the liquid refrigerant is convert-
ed to a gaseous state. The energy needed for this pur-
pose is taken from the enclosure air in the form of heat,
which has the effect of cooling the enclosure air. In the
compressor (2), the refrigerant is heavily compressed,
so that it achieves a higher temperature inside the con-
denser (3) than the ambient air. This means that excess
heat may be emitted to the ambient air via the surface of
the condenser, as a result of which the temperature of
the refrigerant drops and it is converted back into liquid.
It is re-injected into the evaporator coil via a thermostatic
expansion valve (4), which causes it to cool down fur-
ther, and is then once again able to absorb the energy
from the enclosure air in the evaporator coil. The whole
cycle begins again.
3.1.2 Control
The Rittal enclosure cooling units are fitted with an
e-Comfort controller for setting the functions of the cool-
ing unit (see section6 "Operation").
3.1.3 Bus mode
The serial unit interface X2 allows you to create a bus
connection with up to ten cooling units using the master-
slave cable (shielded, four-wire cable, Model No.
3124.100). This allows you to implement the following
functions:
– Parallel unit control (the cooling units in the network
can be switched on and off simultaneously)
– Parallel door status message ("door open")
– Parallel collective fault message
Data is exchanged via the master-slave connection.
During commissioning, assign an address to each unit
that also includes the identifier "master" or "slave".
3.1.4 Safety devices
– In the cooling cycle, the cooling units have a tested
pressure switch to EN 12 263 which is set to maxi-
mum PS (permissible pressure); this operates via an
automatic reset device whenever the pressure drops
again
– Temperature monitoring prevents the evaporator coil
from icing over. If there is a risk of icing, the compres-
sor switches itself off and automatically switches itself
back on again at higher temperatures
– The refrigerant compressor and the fans are equipped
with thermal winding shields to protect against excess
current and excess temperatures
– In order to allow a reduction of pressure inside the
compressor and hence a safe restart, once it has been
switched off (e.g. upon reaching the set temperature
via the door limit switch function or via de-energising),
the device will switch back on with a delay of 180 sec-
onds
– The device has floating contacts on the connection
pins (terminals 3 – 5), via which system messages
from the device may be polled, e.g. using a PLC (1 x
change-over contact Basic controller, 2 x normally
open contacts e-Comfort controller)
3.1.5 Condensation
At high levels of humidity and low temperatures inside
the enclosure, condensation may form on the evapora-
tor coil.
The cooling units (except 3303.xxx) have automatic,
electric condensate evaporation. The thermal compo-
nent used for this purpose is based on self-regulating
PTC technology. Condensate arising on the evaporator
coil is collected in a tank in the external circuit of the
cooling unit, and partially evaporated via the airflow.
When the water level rises, the water enters the PTC
thermal component and is evaporated (through-flow
heater principle). The water vapour streams out of the
cooling unit with the airflow from the external fan.
The PTC thermal component is permanently connected
and has no switchpoint. It is protected against short-cir-
cuits with miniature fuses (F1.1, F1.2). If the fuse has
tripped, any condensation is drained off via the safety
overflow.
For unit types 3303.xxx, the condensate is routed
downwards out of the unit via a drain pipe on the evap-
orator coil divider panel. For this purpose, a hose must
be connected to the condensate nozzle (see section4.4
"Connecting the condensate discharge"). External con-
densate evaporators are available as accessories for
these unit types (refer also to the accessories in the Rittal
Catalogue).
3.1.6 Filter mats
The entire cooling unit condenser is covered with a dirt-
repelling, easy-to-clean RiNano coating. In many appli-
cations, therefore, the use of filter media is unnecessary,
particularly with dry dusts.
For dry, coarse dust and lint in the ambient air, we rec-
ommend installing an additional PU foam filter mat (avail-
able as an accessory) in the cooling unit. Depending on
the incidence of dust, you will need to replace the filter
mat from time to time.
For air containing oil condensate, we recommend the
use of metal filters (also available as an accessory).
PSA
H
-
Pressure
switch
Condenser fan
Expansion valve (4)
Temperature
control
Filter dryer (5)
Internal circuit
Compressor (2)
External circuit
Evaporator fan
Evaporator coil (1)
Condenser (3)