Dwyer MTL5045 - Manual (Page 12)

8 INM5000-6 Jul 2010
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
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
(CENELEC), Factory Mutual Research Corporation, Canadian
Standards Association.
Figure 5.5 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 - δT
where δT = 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 series. Select the relevant value from table 5.2.
(60°C is the temperature inside the enclosure)
Table 5.2: Dissipation constant k
1
for enclosures (°C/watt)
Orientation of the enclosures is also important - the optimum position
being on a vertical surface with the internal DIN-rail horizontal as shown
in figure 5.6. Any other position can reduce the maximum allowable
ambient temperature by up to 5°C.
Examples
Tables 5.3 and 5.4 list likely combinations of MTL5000 Series modules
in the three enclosure types and indicate the acceptable maximum
permitted outside enclosure temperature for these based on the graph in
figure 5.5. See the specifications included in the latest version of MTL's
IS catalogue for the power dissipation figures of individual MTL5000
Series modules.
5.1.2 Storage temperatures
Storage temperatures are safe within the range -40°C to +80°C.
5.1.3 Humidity limits
Safe humidity limits are within the range 5 to 95% RH.
MTL5000 Series Isolators
MTL5000 Series Isolators
DX070 DX170 DX430
MTL5000 4.03 1.88 0.82
60
40
20
10
30
50
0
10 20 30 40
Power dissipation (watts)
Max. outside enclosure
temperature (°C)
Enclosures
DX070
DX170
DX430
Figure 5.3: DX170 enclosure showing MTL5000 modules
mounted
Figure 5.4: DX430 enclosure showing MTL5000 modules
mounted
Figure 5.5: Graph depicting outside enclosure temperature
limits for DX enclosures used with MTL5000 Series isolators
Figure 5.6: Optimum orientation for wall-mounted enclosure