Active Front End (AFE) vacon • 51
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
4
4.16.2 High altitude installation
The density of air decreases when the altitude increases and the pressure decreases. When the air
density decreases, the thermal capacity decreases (i.e. less air removes less heat) and the
resistance to electric field (breakdown voltage / distance) decreases.
The full thermal performance of VACON
®
NX AC drives is designed for installation up to 1000 m
altitude and the electric insulation is designed for installations up to 2000 m altitude. Higher
installation locations are possible, when you obey the derating guidelines in this chapter.
NOTE! 690V units maximum installation altitude is 2000m.
Above 1000 m, you must decrease the limited maximum load current by 1% for each 100 m. Thus,
for example, at 2500 m altitude, you must decrease the load current down to 85% of the rated output
current (100% – (2500 m – 1000 m) / 100 m x 1% = 85%).
When you use fuses at high altitudes, the cooling effect of the fuse decreases as the density of the
atmosphere decreases.
When you use fuses above 2000 meters, the continuous rating of the fuse:
Figure 22. Loadability in high altitudes
For permitted maximum altitudes, see Table 7.
For information on option boards and I/O signals and relay outputs, see VACON
®
NX I/O Boards User
Manual.
I = I
n
*(1- (h-2000)/100*0.5/100)
I = Current rating at high altitude
I
n
= Rated current of a fuse
h = Altitude in meters
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0%
10%
30%
50%
70%
20%
40%
60%
80%
90%
100%
110%
A
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