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Unidrive M/HS Frame 5 to 6 Power Installation Guide
35
Issue Number: 9
Safety i
P
Me
ch
an
ic
E
Te
UL
li
Where:
V
Air-flow in m
3
per hour (1 m
3
/hr = 0.59 ft
3
/min)
T
ext
Maximum expected temperature in
C
outside
the enclosure
T
int
Maximum permissible temperature in
C
inside
the enclosure
P
Power in Watts dissipated by
all
heat sources in the enclosure
k
Ratio of
Where:
P
0
is the air pressure at sea level
P
I
is the air pressure at the installation
Typically use a factor of 1.2 to 1.3, to allow also for pressure-drops in dirty air-filters.
Example
To calculate the size of an enclosure for the following:
•
Three drives operating at the Normal Duty rating
•
External EMC filter for each drive
•
Braking resistors are to be mounted outside the enclosure
•
Maximum ambient temperature inside the enclosure: 40
C
•
Maximum ambient temperature outside the enclosure: 30
C
For example, dissipation of each drive: 101 W and dissipation of each external EMC filter: 6.9 W
(max).
Total dissipation: 3 x (101 + 6.9) = 323.7 W
Insert the following values:
T
int
40
C
T
ext
30
C
k
1.3
P
323.7 W
Then:
=
126.2 m
3
/hr (74.5 ft
3
/min)
(1 m
3
/ hr = 0.59 ft
3
/min)
P
o
P
l
-------
V
3 1.3
323.7
40 30
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