8 Additional information
BU 0200 en-US-4920
257
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8.4.3 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 (
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 6 kHz pulse frequency, current
above 1.1x the nominal current cannot be taken off.
x f
( )
In_ 60s ec f
( )
In_ 1se c 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]
Inadmissible range
The upper limiting values for the various pulse frequencies can be obtained from the following tables.
The value (10 ... 201) 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%
Table 18: Overcurrent relative to pulse and output frequency
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