NORDAC SK 5xxE Manual
150
Subject to technical alterations
BU 0500 GB
8.5 Reduced output power
The SK 5xxE frequency inverter series is designed for certain overload situations. For example, 1.5x
overcurrent can be used for 60 sec. For approx. 3.5 sec a 2x overcurrent is possible. A reduction of the
overload capacity or its time must be taken into account in the following circumstances:
o
Output frequencies < 2Hz and constant voltages (needle stationary)
o
Pulse frequencies greater than the nominal pulse frequency (P504)
o
Increased mains voltage > 400V
o
Increased heat sink temperature
On the basis of the following characteristic curves, the particular current / power limitation can be read off.
8.5.1 Increased heat dissipation due to pulse frequency
This illustration shows how the output current must be reduced, depending on the pulse frequency for 230V
and 400V devices, in order to avoid excessive heat dissipation in the frequency inverter.
For 400V devices, the reduction begins at a pulse frequency above 6kHz. For 230V devices, the reduction
begins at a pulse frequency above 8kHz.
Even with increased pulse frequencies the frequency inverter is capable of supplying its maximum peak
current, however only for a reduced period of time. The diagram shows the possible current load capacity for
continuous operation.
1.2
0.4
k 400V f puls
k 230V f puls
16
3
f puls
4
6
8
10
12
14
16
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
I / I
N
Pulse frequency [kHz]
