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Building Technologies Basic documentation LMV37.4... CC1P7546en
7 Basic unit LMV37.4 17.12.2018
7.5.4.13. Switching back to pilot
The function must be selected with parameter 191. This deactivates the OPEN / CLOSE
load controller contacts (X5-03 pin 2 or 3). Contact X5-03 pin 2 is evaluated as the input
signal for Switching back to pilot. The function can be started either by a low or high
signal. Both the minimum and maximum dwelling time can be set for the pilot flame via
time parameters.
No. Parameter
191 Switching back to pilot
0 = deactivate
1 = active (low active)
2 = active (high active)
Load controller contacts X5-03 are deactivated when function is active!
192 Switching back to pilot minimum time
193 Switching back to pilot maximum time
Note!
Once the OPEN / CLOSE load controller contacts have been deactivated, the analog
input is the lowest-priority load controller source. The system response when the
analog signal is interrupted can be performed via parameter 204 (low-fire or shutdown
and start prevention).
No. Parameter
204 Behavior if analog input is invalid (4…20 mA)
0 = deactivate default output low-fire / trim function (with warning message)
1 = safety shutdown + startup prevention
2 = deactivate default output low-fire / trim function (without warning
message)
Sequence following activation of input signal in operation (phase 60) – (also refer to
Sequence diagram):
1. Phase 64: Modulation to ignition load
2. Phase 65: Interval 2 waiting time (stabilization time)
3. Phase 66: Reactivation of ignition and pilot valve (duration of the first safety time)
4. Phase 67: Shutdown of the main valves (duration of the first safety time, including
blind circuit for pressure switch-min / pressure switch-max)
5. Phase 68: Pilot mode waiting phase (pilot minimum time / pilot maximum time)
The LMV37.4 is restarted (via second safety time) when the input signal no longer
exists.
Shutdown of the LMV37.4 in the event of:
Load controller OFF
Maximum pilot time exceeded (maximum setting 108 minutes)
Forced intermittent operation after 24 hours
When the input signal is active during startup, the LMV37.4 waits in phase 69 (interval
1). While the switching back to pilot function is in use, the remaining time to shutdown is
displayed via the maximum time in the AZL2.
Note!
A user intervention has top priority. This means that an active curve setting or
preselected manual output (signaled by flashing output display) prevents the
switching back to pilot function from being activated.
The restarts from the pilot waiting phase are counted in the startup counter (parameter
176).
No. Parameter
176 Switching back to pilot switching cycles
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