INM 5500 Rev 11
12
5
DX ENCLOSURES
Enclosures are usually selected on the basis of the number of units they will accommodate and
Table 5.1 shows the capacity of each of the enclosures. Figure 5.2 shows each type of enclosure
containing MTL5500 modules.
Table 5 .1
: DX range of enclosures - module capacities
Enclosure
Number of MTL5500 isolators
16mm mounting pitch
DX070
4 (2*)
DX170
10 (8*)
(DX430)
26 (24*) no longer available
* Use these figures when two IMB57 mounting brackets for tagging/earth-rail accessories are included.
Note
:
The user should be aware that some workshop preparation may be required for the cable gland
plates before the enclosure is ready for on-site installation.
5 .1 Environmental conditions
Environmental conditions that should be taken into account when installing DX enclosures include:-
See section
Maximum ambient temperature limits
5.1.1
Storage temperatures
5.1.2
Humidity
5.1.3
Corrosion resistance
5.1.4
Flammability
5.1.5
Impact resistance
5.1.6
Chemical resistance
5.1.7
5 .1 .1 Maximum outside enclosure temperature limits
Figure 5 .1: Graph depicting outside enclosure temperature limits for DX enclosures used
with MTL5500 isolators
The maximum outside enclosure temperature depends upon the total power dissipated by the
installed modules which, in turn, depends upon their number and type. It can also be influenced by
the Authority whose standards may need to be applied to the system, e.g. Baseefa, Factory Mutual
Research Corporation, Canadian Standards Association.
Figure 5.1 shows, in graphical form, the maximum outside enclosure temperatures (T
MO
) for given
levels of power dissipation.
The graph was derived from the following equation and should be used to calculate accurately the
suitability of any particular mix of modules.
T
MO
= 60°C - ∂T
where ∂T = k
1
x P
P = total power (watts) dissipated by modules in an enclosure
k
1
= is a dissipation constant for a given enclosure and module . Select the relevant value from
Table 5.2.
(60°C is the temperature inside the enclosure)
60
40
20
10
30
50
0
10
20
30
40
Power dissipation (watts)
Max. outside enclosure
temperature (°C)
Enclosures
DX070
DX170
DX430
