SIEMENS
SINAMICS DCM
Engineering information
Dynamic overload capability
5/3
Siemens D 23.1 · 2014
5
■
Overview
(continued)
Basic task 1
• Given:
Unit, cycle duration, overload factor, overload duration
•
To be found:
(Min.) base-load duration and max. base-load current
• Solution:
Example for basic task 1
• Given:
- Unit with 30 A
- Cycle duration 113.2 s
- Overload factor 1.45
- Overload duration 20 s
•
To be found:
- (Min.) base-load duration
- Max. base-load current
• Solution:
- Limiting characteristic for a unit with 30 A
- Overload factor 1.5
- Overload duration
300
= 300 s/113.2 s
×
20 s = 53 s
→
- Max. base-load current = 44 %
I
rated
= 13.2 A
Basic task 2
• Given:
Unit, cycle duration, overload factor, base-load current
•
To be found:
Maximum overload duration, minimum base-load duration
• Solution:
Example for basic task 2
• Given:
- Unit with 30 A
- Cycle duration 140 s
- Overload factor 1.15
- Base-load current = 0.6
×
I
rated
= 18 A
•
To be found:
- Maximum overload duration
- Minimum base-load duration
• Solution:
- Limiting characteristic for a unit with 30 A
- Overload factor 1.2
- Base-load current = 60 %
I
rated
→
- Overload duration
300
= 127 s
- Max. overload duration = 140 s/300 s
×
127 s = 59 s
- Min. base-load duration = 140 s - 59 s = 81 s
Explanation of terms:
Base-load duration
300
= min. base-load duration for 300 s
cycle duration (300 s
–
overload duration)
Overload duration
300
= max. overload duration for 300 s cycle
duration
Cycle duration
< 300 s
≥
300 s
1. Determine the characteristic
Select the limiting characteristic for the specific unit and the specific overload factor
2. Overload duration
300
=
300 s/cycle duration
×
overload duration
Overload duration
300
3. Base-load duration
300
=
300 s – overload duration
300
4. Base-load duration
300
< base-load
duration
300
for max. base-load current = 0
Yes
: Required duty cycle cannot be configured
No
: Read the max. base-load current for overload duration
300
from the limiting characteristic
5. Determine the percentage for the base-load
current
Read the percentage for the base-load currents from the diagram
Cycle duration
< 300 s
≥
300 s
1. Determine the characteristic
Select the limiting characteristic for the specific unit and the specific overload factor
2. Max. overload duration =
(Cycle duration/300 s)
×
overload duration
300
300 s – base-load duration
300
3. Min. base-load duration =
Cycle duration – max. overload duration
Cycle duration – max. overload duration
© Siemens AG 2014