Siemens LFL1.322 - Detailed Functionality and Safety; General Safety Features; Burner Control Operation; Flame Supervision and Startup Preconditions

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Building Technologies Division CC1N7451en
20.11.2017
Function (cont'd)
The following features enable the LFL1... to offer a high level of additional safety:
- Detector and extraneous light test are resumed immediately on completion of the
afterburn time «t13». Fuel valves that are not closed, or not fully closed,
immediately initiate lockout on completion of the afterburn time «t13». The test will
only be terminated when the prepurge time «t1» of the next startup sequence has
elapsed.
- The proper functioning of the flame supervision circuit is automatically checked
during each startup phase of the burner.
- During the postpurge time «t6», the control contacts for the release of fuel are
checked to ensure they have not welded.
- The built-in unit fuse protects the control contacts against overloads.
- Burner operation with or without postpurging
- Fan motors with a current draw of up to 4 A can be connected directly  starting
current max. 20 A (max. 20 ms)
- Separate control outputs for one pilot valve, which will be shut on completion of the
second safety time
- Separate control outputs for the actuator’s positioning directions «OPEN»,
«CLOSE» and «MIN»
- Checked air damper control to ensure prepurging with the nominal amount of air
- Checked positions:
- «CLOSED» or «MIN» on startup
 low-fire position
- «OPEN» at the start of prepurging
- «MIN» on completion of prepurging
If the actuator does not drive the air damper to the required position, the burner
startup sequence will be stopped
- 2 control outputs for the release of the second and third output stage, or load control
- When load control is enabled, the control outputs for the actuator will galvanically
be separated from the unit’s control section
- Connection facilities for
- remote lockout warning device
- remote reset
- remote emergency shutdown
- With burner controls of the 01 series and direct spark flame burners, the safety time
can be increased from 2.5 to 5 seconds by changing the circuitry (refer to
«Connection examples»), provided the longer safety time conforms to local safety
regulations
- With the ionization probe, in networks with earthed or nonearthed neutral
conductor. For this kind of supervision, the flame supervision circuit is designed
such that possible disturbances of the ionization current due to the ignition spark
normally have no impact on the establishment of the flame signal. A short-circuit
between ionization probe and burner ground causes loss of the flame signal
- With UV detector QRA2 / QRA4 / QRA10 (gas and oil burners)
- Simultaneous use of ionization probe and UV detector QRA2 / QRA4 / QRA10 (e.g.
with interrupted pilot burners or gas-electrically ignited oil burners)
- If, on startup, the required input signals are not present, the burner control
interrupts the startup sequence at the points marked by symbols and initiates
lockout where required by safety regulations. The symbols used in this Data Sheet
correspond to those on the burner control’s lockout indicator.
General
Control of the burner
Flame supervision
Preconditions for
startup