Siemens SINAMICS DCM Operating Instructions Manual page 444

Descriptions of functions
10.20 Dynamic overload capability of the power unit
The limiting characteristic fields apply for a duty cycle duration of 300 s.
For cycle durations < 300 s, the overload duration must be reduced proportionally (cycle
duration/300 s).
For cycle durations > 300 s, only the same overload duration as with a cycle duration of
300 s is permitted; the base load duration is correspondingly longer.
The limiting characteristic fields apply for p50077 = 1.00. When setting p50077 to ≤ 1.00, i.e.
reducing the thermal load, the currents that are actually flowing must be evaluated with the
factor 1/p50077:
Overload factor for characteristic X:
X =
Actual maximum base-load current Ig:
Ig = p50077 × maximum base-load current acc. to characteristic
Basic tasks for configuring periodic operation with overload
Designations:
Base load duration
Overload duration
Basic task 1
Known:
Device types, cycle duration, overload factor, overload duration
To be found:
Minimum base load duration and maximum base-load current
To reach solution:
Select the limiting characteristic for the known unit and overload factor
Cycle duration < 300 s:
Overload duration
Cycle duration ≥ 300 s:
Overload duration
If:
Then:
Otherwise
:
442
Actual overload current / (p50077×rated unit DC current)
as a % of the rated unit DC current
= Minimum base load duration for 300 s cycle duration
300
= Maximum overload duration for 300 s cycle duration
300
= (300 s/cycle duration) × overload duration
300
= Overload duration
300
Overload duration
300
Required duty cycle cannot be configured
Read the maximum base-load current for overload duration
characteristic
> overload duration
300
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
for base-load current = 0
from the limiting
300
SINAMICS DCM DC Converter