Emerson Unidrive M201 Installation Manual page 33

Where:
V Air-flow in m
Maximum expected temperature in °C outside the enclosure
T
ext
T Maximum permissible temperature in °C inside the enclosure
int
P Power in Watts dissipated by all heat sources in the enclosure
P
------ -
k Ratio of
P
Where:
P is the air pressure at sea level
0
P is the air pressure at the installation
I
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:
40 °C
T
int
T 30 °C
ext
k 1.3
P 323.7 W
Then:
× ×
3 1.3
V = -------------------------------------- -
40 30 –
3
= 126.2 m /hr (74.5 ft
Unidrive M / HS Frame 7 to 10 Power Installation Guide
Issue Number: 5
3 3
per hour (1 m /hr = 0.59 ft
o
l
323.7
3 3
/min) (1 m / hr = 0.59 ft
3
/min)
3
/min)
33