Unidrive M400 User Guide
27
Issue Number: 2
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)
3.7 Enclosure design and drive ambient
temperature
Drive derating is required for operation in high ambient temperatures
Totally enclosing or through panel mounting the drive in either a sealed
cabinet (no airflow) or in a well ventilated cabinet makes a significant
difference on drive cooling.
The chosen method affects the ambient temperature value (T
rate
) which
should be used for any necessary derating to ensure sufficient cooling
for the whole of the drive.
The ambient temperature for the four different combinations is defined
below:
1. Totally enclosed with no air flow (<2 m/s) over the drive
T
rate
= T
int
+ 5 °C
2. Totally enclosed with air flow (>2 m/s) over the drive
T
rate
= T
int
3. Through panel mounted with no airflow (<2 m/s) over the drive
T
rate
= the greater of T
ext
+5 °C, or T
int
4. Through panel mounted with air flow (>2 m/s) over the drive
T
rate
= the greater of T
ext
or T
int
Where:
T
ext
= Temperature outside the cabinet
T
int
= Temperature inside the cabinet
T
rate
= Temperature used to select current rating from tables in
3.8 Heatsink fan operation
The drive is ventilated by an internal heatsink fan. The fan channels air
through the heatsink chamber.
Ensure the minimum clearances around the drive are maintained to
allow air to flow freely.
The heatsink fan on size 1, 2, 3, and 4 frames is a variable speed fan.
The drive controls the speed at which the fan runs based on the
temperature of the heatsink and the drive's thermal model system. The
maximum speed at which the fan operates can be limited in Pr
06.045
.
This could incur an output current derating.
V
3 1.3
×
323.7
×
40 30
–
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=
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