Device Description; Functional Description; How It Works; Control - Rittal SK 3302.100 Assembly And Operating Instructions Manual

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Device description

Depending on the model chosen, your cooling unit
may vary in appearance from the illustrations con-
tained in these instructions. However, the functions
are identical in principle.
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2
3
4
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Fig. 1: Device description
Legend
1 Blind rivet nut
2 Evaporator fan
3 Electrical wiring plan
4 X2 master-slave connection
5 X3 optional serial interface
6 X1 terminal strip
7 Air outlet hole
8 Front half of the enclosure
9 Rear half of the enclosure
10 Louvred grille for air outlet
11 Display
12 Infill panel
13 Louvred grille for air inlet
14 Rating plate
15 Condensate discharge
16 Dispatch bag

3.1 Functional description

Enclosure cooling units are designed to dissipate
heat from enclosures by cooling the air inside the
enclosure and so protect the temperature-sensitive
components. They are built into the side or rear
panel or into the door of the enclosure.

3.1.1 How it works

The cooling unit (compression refrigeration system)
is comprised of four main components (cf. Fig. 2):
the evaporator (1), the coolant compressor (2), the
condenser (3), and the control or expansion valve
(4), which are connected by suitable pipework. This
circuit is filled with a readily boiling substance, the
refrigerant. Coolant R134a (CH
free. Its ozone destruction potential is 0, making it
very eco-friendly. A filter dryer (5) which is integrated
Rittal cooling unit assembly and operating instructions
into the hermetically sealed cooling circuit provides
effective protection against moisture, acid, dirt
particles, and foreign bodies within the cooling
circuit.
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14
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Fig. 2:
In the evaporator coil (1), the liquid coolant is con-
verted to a gaseous state. The energy needed for
this purpose is taken from the enclosure air in the
form of heat, which has the effect of cooling the
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enclosure air. In the compressor (2), the coolant is
heavily compressed, so that it achieves a higher
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temperature inside the condenser (3) than the ambi-
ent 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 coolant
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
further, 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

Rittal enclosure cooling units are fitted with a con-
troller for setting the functions of the cooling unit.
Depending on the design, this is either a Basic con-
troller (display of the operating status via LED) or a
e-Comfort controller (display plus extended func-
tions, see chapter "6 Operation", page 21).

3.1.3 Bus mode (e-Comfort controller only)

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. SK 3124.100). This allows you to implement the
following functions:
– Parallel unit control (the cooling units in the network
– 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".
FCF ) is chlorine-
2 3
3 Device description
H
PSA
pressure-
operated
switch
Condenser fan
Compressor
(2)
External circuit
Internal circuit
Evaporator coil (1)
Evaporator fan
Cooling circuit
can be switched on and off simultaneously)
EN
Condenser (3)
Filter dryer (5)
Temperature
control
Expansion valve (4)
5