4
vacon • 50 Active Front End (AFE)
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4.16 Derating
The output power has to be derated if one of following cases:
• Ambient temperature is more than 40 ºC (104 °F).
• Installation altitude is more than 1000 m.
4.16.1 Ambient Temperature
The power rating of the Active Front End unit is valid for an ambient temperature of 40 ºC (104 °F).
If the device is to be used in higher ambient temperatures, its power rating must be subjected to
derating. The derating coefficient from 40 °C to 50 °C, use derating factor 1.5 %/1 °C, and from 50
°C to 55 °C, use derating factor 2.5 %/1 °C, for ambient temperatures not exceeding 55 °C (131 °F).
The reduced power is calculated using the formula:
Figure 21. Derating as the ambient temperature
P
de
= P
n
*((100% - (t - 40 ºC)*X)/100)
P
n
= nominal power of the unit
t = ambient temperature
x = derating coefficient
A Ambient temperature, °C
BLoadability, %
CLoadability %
C
11167A_00
0
10
20
30
40
50
60
0%
20%
40%
60%
80%
100%
120%
B
A
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