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SYSTEM AND MODULE DATA
Operation in the range of the thermal overload limit
Due to the high steepness of the overload characteristic, the duration of a permissible
overload in this range cannot be determined exactly. Therefore, the design of the drive
inverter should be assumed to have a maximum overload time of 300s.
3.2.5.2 Frequency-dependent maximum current (OL2)
The characteristics of the maximum currents for a switching frequency which are de-
pending on the output frequency are different for each drive inverter, but the following
rules are generally applicable:
•
If error (OL2) shall be triggered on exceeding the maximum currents or if the switching
frequency is automatically reduced (derating) can be adjusted in the drive inverter pa-
rameters.
The following characteristic curve indicates the permissible maximum current for the
output frequency values 0 Hz, 3 Hz, 6 Hz, 12,5 Hz 25 Hz and 50 Hz. Module A is shown
as an example.
240
220
200
180
160
140
120
100
80
60
40
20
0
0
5
10
Legend
Overcurrent I
OC
Software current limit I
Switching frequency 8 kHz
Switching frequency 16 kHz
Not available for modulation. Error OC is triggered at 180% overload.
Figure 7:
Typical overload characteristic in the lower output frequencies (OL2) Example module A
42
Lower maximum currents apply for switching frequencies > rated switching frequency.
15
20
25
Output frequency in Hz
(the limit can be set with parameter is35)
lim
The frequency-dependent maximum current I
current I
.
N
The current remains constant from the last specified output frequency value.
30
35
40
45
refers in % to the rated output
lim
50
55
60
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