Siemens 6RA7086-6KS22 Operating Instructions Manual page 392

Function descriptions
Basic tasks for configuring periodic overload operation
Terms:
Basic task 1:
Known quantities: Converter type, cycle time, overload factor, overload period
Quantities to be found: Minimum base-load duty period and maximum base-load current
Solution:
Example 1:
Known quantities: 30A/4Q converter; cycle time 113.2s; overload factor = 1.45; overload period = 20s
Quantities to be found: Minimum base-load period and maximum base-load current
Solution:
Basic task 2:
Known quantities: Converter type, cycle time, overload factor, base-load current
Quantities to be found: Minimum base-load period and maximum overload period
Solution:
Example 2:
Known quantities: 30A/4Q converter; cycle time 140s; current overload factor = 1.15;
Quantities to be found: Minimum base-load period and maximum overload period
Solution:
9-36
Base-load duty period
Overload period
300
Selection of limit characteristic for specified converter type and overload factor
Cycle time < 300s: Overload period
Cycle time ≥ 300s: Overload period
If: Overload period > overload period
300
Then: Required load cycle cannot be configured,
Otherwise: Determine the maximum base-load current for overload period
limit characteristic
Limit characteristic for 30A/4Q converter, overload factor 1.5
Overload period = (300s/113.2s) * 20s = 53s
300
= 300s – 53s = 247s →
Base-load period
300
Maximum base-load current = approx. 45% of I
Selection of limit characteristic for specified converter type and overload factor
Determine overload period
Cycle time < 300s:
Max. overload period = (cycle time/300s) * overload period
Min. base-load period = cycle time – max. overload period
Cycle time ≥ 300s:
Max. overload period = overload period
Min. base-load period = cycle time – max. overload period
base-load current = 0.6*I
Limit characteristic for 30A/4Q converter, overload factor 1.2
Base-load current = 60% of I
Max. overload period = (140s/300s) * 126.35s = approx. 58s
Min. base-load period = 140s – 58s = 82s
= min. base-load duty period for 300 s cycle time
300
= max. overload period for 300 s cycle time
= (300s/cycle time) * overload period
300
= Overload period
300
for base-load current = 0
300
for base-load current from limit characteristic
300
300
= 18A
rated
→ overload period
rated
= 13.5A
rated
300
= 126.35s
300
SIEMENS AG
SIMOREG DC Master
05.05
from the
300
6RX1700-0AD76
Operating Instructions