nord NORDAC FLEX SK 2 E-111-123-A Series, Руководство пользователя

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8 Additional information
BU 0200 en-US-4920 255
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8.4 Reduced output power
The variable frequency drives are designed for specific overload situations. For example, 1.5x
overcurrent can be used for 60 s. For approx. 3.5 s a 2x overcurrent is possible. Reduction of the
overload capacity or its time must be taken into account in the following circumstances:
• Output frequencies < 4.5 Hz and constant voltages (needle stationary)
• Pulse frequencies greater than the nominal pulse frequency (P504)
• Increased line voltages > 400 V
• Increased heat sink temperature
On the basis of the following characteristic curves, the particular current/power limitation can be read
off.
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8.4.1 Increased heat dissipation due to pulse frequency
This illustration shows how the output current must be reduced, depending on the pulse frequency for
230 V and 400 V devices, in order to avoid excessive heat dissipation in the variable frequency drive.
For 400 V devices, the reduction begins at a pulse frequency above 6 kHz. For 230 V devices, the
reduction begins at a pulse frequency above 8 kHz.
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]
Figure 34: Heat losses due to pulse frequency
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