Siemens SINAMICS DCM Operating Instructions Manual page 445

Example 1:
Known:
30 A/4Q unit; cycle duration 113.2 s; overload factor = 1.45; overload duration = 20 s
To be found:
Minimum base load duration and maximum base-load current
Solution:
Limiting characteristic for 30 A/4Q unit, overload factor 1.5
Overload duration
Base load duration
Maximum base-load current = approx. 45% of I
Basic task 2
Known:
Device types, cycle duration, overload factor, base-load current
To be found:
Minimum base load duration and maximum overload duration
To find solution:
Select the limiting characteristic for the known unit and the known overload factor.
Read the overload duration
Cycle duration < 300 s:
Max. overload duration = (cycle duration/300 s) * overload duration
Min. base load duration = cycle duration – max. overload duration
Cycle duration ≥ 300 s:
Max. overload duration = overload duration
Min. base load duration = cycle duration – max. overload duration
Example 2:
Known:
30 A/4Q unit; cycle duration 140 s; current-overload factor = 1.15; base-load current =
0.6*IN=18 A
To be found:
Minimum base load duration and maximum overload duration
Solution:
Limiting characteristic for 30 A/4Q unit, overload factor 1.2
Base-load current = 60% of I
Max. overload duration = (140 s./300 s.)×126.35 s. = approx. 58 s.
Min. base load duration = 140 s. – 58 s. = 82 s.
SINAMICS DCM DC Converter
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
= (300 s./113.2 s.)×20 s. = 53 s.
300
= 300 s. – 53 s. = 247 s. →
300
for the base-load current from the limiting characteristic.
300
→ overload duration
N
10.20 Dynamic overload capability of the power unit
= 13.5 A
N
300
= 126.35 s.
300
Descriptions of functions
300
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