Nord Drivesystems SK 180E Series, User Manual

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NORDAC BASE (SK 180E / SK 190E) – Users Manual for Frequency Inverters
188 BU 0180 en-4118
8.4.3 Reduced overcurrent due to output frequency
To protect the power unit at low output frequencies (<4.5Hz) a monitoring system is provided, with
which the temperature of the IGBTs ( insulated - 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 6kHz pulse frequency, current
above 1.1x the nominal current cannot be taken off.
x f
( )
In_60s ec f
( )
In_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.
230V 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%
400V 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%
Table 16: Overcurrent relative to pulse and output frequency