Nidec Digitax HD M75 Series, Инструкция по установке и техническое руководство

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Digitax HD M75X Series Installation and Technical Guide
31
Issue Number: 5
P Power in Watts dissipated by all heat sources in the enclosure
k Heat transmission coefficient of the enclosure material in W/m
2
/°C
Example
To calculate the size of an enclosure for the following:
•
Two drives operating
• 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, if the power dissipation from each drive is 187 W and the power dissipation from each external EMC filter is 9.2 W.
Total dissipation: 2 x (187 + 9.2) = 392.4 W
Power dissipation for the drives and the external EMC filters can be obtained from Chapter 6 Technical data on page 98.
The enclosure is to be made from painted 2 mm (0.079 in) sheet steel having a heat transmission coefficient of 5.5 W/m
2
/
o
C. Only the top, front, and
two sides of the enclosure are free to dissipate heat.
The value of 5.5 W/m
2
/ºC can generally be used with a sheet steel enclosure (exact values can be obtained by the supplier of the material). If in any
doubt, allow for a greater margin in the temperature rise.
Figure 3-18 Enclosure having front, sides and top panels free to dissipate heat
Insert the following values:
T
int
40 °C
T
ext
30 °C
k 5.5
P 392.4 W
The minimum required heat conducting area is then:
= 7.135 m
2
(77.8 ft
2
) (1 m
2
= 10.9 ft
2
)
Estimate two of the enclosure dimensions - the height (H) and depth (D), for instance. Calculate the width (W) from:
Inserting H = 2 m and D = 0.6 m, obtain the minimum width:
= 1.821 m (71.7 in)
If the enclosure is too large for the space available, it can be made smaller only by attending to one or all of the following:
•
Using a lower PWM switching frequency to reduce the dissipation in the drives
• Reducing the ambient temperature outside the enclosure, and/or applying forced-air cooling to the outside of the enclosure
• Reducing the number of drives in the enclosure
• Removing other heat-generating equipment
• Using rear vent duct
Calculating the air-flow in a ventilated enclosure
The dimensions of the enclosure are required only for accommodating the equipment. The equipment is cooled by the forced air flow.
Calculate the minimum required volume of ventilating air from:
NOTE
W
H
D
Ae
392.4
5.5 40 30 –
 
---------------------------------
=
W
Ae 2HD –
H D +
--------------------------
=
W
7.135 2 2

0.6
  
–
2 0.6
+
-----------------------------------------------------
=
V
3kP
Tint Text –
-------------------------------
=