Siemens MICROMASTER 411 - Manual (Page 135)

Issue 03/01 10 Engineering Information
MICROMASTER 411 & COMBIMASTER 411 Operating Instructions
6SE6400-5CA00-0BP0 135
10.4 Derating Factors
10.4.1 Derating with Temperature
Operation of the inverter outside its recommended ambient operating temperature
would normally cause the inverter to trip with an overtemperature fault code. To
avoid such tripping, the inverter automatically reduces its switching frequency (e.g.
from 16 kHz to 8 kHz), thus reducing the temperature of the heatsink, enabling the
application to continue running trip free. Should the load or ambient temperature
then reduce, the inverter will first check to see if it is safe to increase the switching
frequency again and if considered safe will then do so.
80
60
40
0
20
100
-10 0 70 10 20 30 40 50 60
°C
%
Rat
ed Out
put
Current
Figure 10-16 Reduktionsfaktoren durch die Umgebungstemperatur
10.4.2 Derating with Altitude
Figure 10-17 shows the permissible rated input voltage and output current for
inverter installations from 500 m to 4000 m above sea level.
Input
v
ol
tage
Permissible rated input voltage as a
percentage of the nominal voltage
100
90
80
60
70
1000 2000 3000 4000 500 500
100
90
80
60
70
1000 2000 3000 4000
Permissible rated output current as a
percentage of the nominal current
Rat
ed out
put
c
urrent
Installation altitude in meters above sea level
Figure 10-17 Derating with Altitude