Siemens LME39 Series Basic Documentation page 17

Note on parameterization:
Use the AZL2... or ACS410 to always set the exact value of the required time (multiples of increments of 0.147 seconds, 0.294 seconds or 4.851 seconds).
When parameterizing minimum or maximum times, the possibility of a ±7% tolerance must be taken into consideration.
For minimum values: The value to be parameterized must be at least 7% greater. For maximum values: The value to be parameterized must be at least 7% smaller.
Example:
Calculation:
Value to be parameterized
(parameter 225):
Example:
Special case here:
Calculation:
Value to be parameterized
(parameter 257):
Legend tfz Flame detection time
TSA
Safety time
tw
Waiting time
t1
Prepurge time
t1´
Purge time
t3
Preignition time
t3n
Postignition time (parameter 257 + 0.3 seconds)
1)
Maximum running time available for actuator. The actuator's running time must be shorter, otherwise, the actuator will not reach the required position
Building Technologies Division
Prepurge time shall be set to 30 seconds
30 seconds + 7% = 32.1 seconds
Must be equal to or greater than the calculated value (e.g. 32,34 seconds)
Safety time shall be set via the change of postignition time to 5 seconds
Safety time is set directly via the change of postignition time and flame detection time using the following formula:
TSA = t3n + tfz = P257 + 0.3 seconds + P228
5 seconds - 7% = 4.65 seconds
t3n = 4.65 seconds - 0.3 seconds - P228
t3n = 4.05 seconds (with tfz = 0.3 seconds)
Must be equal to or smaller than the calculated value (e.g. 3.969 seconds)
t4 Interval between ignition OFF and release fuel valve 2
t8
Postpurge time
t10
Specified time for air pressure signal
t11
Programmed opening time for actuator
t12
Programmed closing time for actuator
t22
2nd safety time
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08.12.2017