Rittal SK 3302.series Assembly And Operating Instructions Manual - 3 Device Description
3 Device description
Rittal cooling unit assembly instructions
5
GB
3
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.
Fig. 1: Device description
Key
1
Blind 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
Controller
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 protecting 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 (see 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
2
FCF
3
) is chlorine-
free. Its ozone destruction potential is 0, making it
very eco-friendly. A filter dryer (5) which is integrated
into the hermetically sealed cooling circuit provides
effective protection against moisture, acid, dirt par-
ticles, and foreign bodies within the cooling circuit.
Fig. 2: Cooling circuit
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
enclosure air. In the compressor (2), the coolant is
heavily compressed, so that it achieves a higher
temperature inside the condenser (3) than the
ambient air. This means that excess heat may be
emitted to the ambient air via the surface of the con-
denser, 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 thermo-
static 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 Controller
Rittal enclosure cooling units are fitted with a control-
ler 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
Comfort controller (display plus extended functions,
see chapter “6 Operation”, page
22
).
3.1.3 Bus mode (Comfort controller only)
The serial interface X2 allows you to create a bus
connection with up to 10 cooling units using the
master/slave cable (shielded, four-wire cable,
Model No. SK 3124.100). This allows you to imple-
ment 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, an address is assigned
to each device which also includes the identifier
“master” or “slave”.
10
9
8
11
13
12
16
15
14
1
2
4
5
6
7
3
PSA
H
pressure-
operated
switch
Condenser fan
Expansion valve (4)
Temperature
control
Filter dryer (5)
Internal circuit
Compressor (2)
External circuit
Evaporator fan
Evaporator coil (1)
Condenser (3)