NORD Drivesystems BU0180 - Manual (Page 167)

9 Additional Information
BU 0180 GB-0914 Pre-series version 167
9.4.3 Reduced overcurrent due to output frequency
To protect the power unit at low output frequencies (<4.5 Hz) a monitoring system is provided, with which
the temperature of the IGBTs (integrated gate bipolar transistor) due to high current is determined. In order
to prevent current being taken off above the limit shown in the diagram, a pulse switch-off (P537) with a
variable limit is introduced. At a standstill, with 6 kHz pulse frequency, current above 1.1x the nominal
current cannot be taken off.
k max f ( )
k 1.5In_60sec f ( )
k 2.0In_1sec f ( )
f
0 2 4 6 8 10 12 14 16 18 20
0
0.5
1
1.5
2
2.5
I / I
N
Output frequency [Hz]
Prohibited region
The upper limiting values for the various pulse frequencies can be obtained from the following tables. In all
cases, the value (0.1…1.9) which can be set in parameter P537, is limited to the value stated in the tables
according to the pulse frequency. Values below the limit can be set as required.
230 V devices: Reduced overload capacity (approx.) due to pulse frequency (P504) and output frequency
Pulse frequency [kHz]
Output frequency [Hz]
4.5 3.0 2.0 1.5 1.0 0.5 0
3...8 200% 170% 150% 140% 130% 120% 110%
10 180% 153% 135% 126% 117% 108% 100%
12 160% 136% 120% 112% 104% 96% 95%
14 150% 127% 112% 105% 97% 90% 90%
16 140% 119% 105% 98% 91% 84% 85%
400 V devices: Reduced overload capacity (approx.) due to pulse frequency (P504) and output frequency
Pulse frequency [kHz]
Output frequency [Hz]
4.5 3.0 2.0 1.5 1.0 0.5 0
3...6 200% 170% 150% 140% 130% 120% 110%
8 165% 140% 123% 115% 107% 99% 90%
10 150% 127% 112% 105% 97% 90% 82%
12 130% 110% 97% 91% 84% 78% 71%
14 115% 97% 86% 80% 74% 69% 63%
16 100% 85% 75% 70% 65% 60% 55%