NORD Drivesystems BU0180 - Manual (Page 168)

SK 180E Manual for frequency inverters
168 Pre-series version BU 0180 GB-0914
9.4.4 Reduced output current due to mains voltage
The devices are designed with thermal characteristics according to the nominal output currents.
Accordingly, for lower mains voltages, higher currents cannot be taken off in order to maintain the stated
power constant. For mains voltages above 400 V there is a reduction of the permissible continuous output
current, which is inversely proportional to the mains voltage, in order to compensate for the increased
switching losses.
1.2
0.4
k Unetz Unetz ( )
480 320 Unetz
320 340 360 380 400 420 440 460 480
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
Mains voltage [V]
I / I
N
9.4.5 Reduced output current due to the heat sink temperature
The temperature of the heat sink in included in the calculation of the reduction of output current, so that at
low heat sink temperatures, a higher load capacity can be permitted, especially for higher pulse frequencies.
At high heat sink temperatures, the reduction is increased correspondingly. The ambient temperature and
the ventilation conditions for the device can therefore be optimally exploited.