Overcurrent Operation - Lenze i550 Series Project Planning Manual

Overcurrent operation

The inverters can be driven at higher amperages beyond the rated current if the duration of
this overcurrent operation is time limited.
Two utilisation cycles of 15 s and 180 s are defined. Within these utilisation cycles, an overcur-
rent is possible for a certain time if afterwards an accordingly long recovery phase takes place.
Cycle 15 s
During this operation, the inverter may be loaded for 3 s with up to 200 % of the rated current
if afterwards a recovery time of 12 s with max. 75 % of the rated current is observed. A cycle
corresponds to 15 s.
Cycle 180 s
During this operation, the inverter may be loaded for 60 s with up to 150 % of the rated cur-
rent if afterwards a recovery time of 120 s with max. 75 % of the rated current is observed. A
cycle corresponds to 180 s.
The monitoring of the device utilisation (Ixt) causes the set error response if one of the two
utilisation values exceeds the threshold of 100 %.
The maximum output currents correspond to the switching frequencies and the
overload behaviour of the inverters are given in the rated data.
In case of rotating frequencies < 10 Hz, the time-related overload behaviour
may be reduced.
The graphics shows a cycle. The basic conditions given in the table (graphics field highlighted
in grey) have to be complied with in order that the inverter will not be overloaded. Both cycles
can be combined with each other.
Max. output current
A
%
Cycle 15 s 200
Cycle 180 s 150
I [%]
A
T T
1
100
B
0
Max. overload time
T
1
s
3
60
Information on project planning
2
t
Max. output current during
the recovery time
B
%
75
75
Project planning process
Overcurrent operation
Min. recovery time
T
2
s
12
120
31