Siemens LAL2.25 - Startup Sequence; Initial Startup Phases; Postignition and Sequence Progression

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Building Technologies Division CC1N7153en
21.09.2016
Startup sequence
A Start command by «R»
 «R» closes the start control loop between terminals 4 and 5
 The sequence switch starts to run
- Only prepurging, fan motor at terminal 6 receives power
- Pre- and postpurging, fan motor or flue gas fan at terminal 7 receives power on completion of «t7»
 On completion of «t16», the control command for opening the air damper is delivered via terminal 9
 Terminal 8 receives no power during the positioning time
 The sequence switch continues to run only after the air damper has fully closed
t1 Prepurge time with air damper fully open
 The correct functioning of the flame supervision circuit is checked during «t1»
 The burner control will initiate lockout if correct functioning is not ensured
With LAL2 / LAL3:
Shortly after the beginning of «t1», the air pressure switch must change over from terminal 13 to terminal 14
 otherwise, the burner control will initiate lockout
 start of the air pressure check
t3 Short preignition time
«Z» must be connected to terminal 16, release of fuel via terminal 18.

For use in applications with short preignition, the oil supply must be equipped with two shutoff
valves connected in series.
Observe the following:
EN 298:2012, Section 7.101.3.3 Prepurge time for oil burner control systems and the
corresponding application standards.
t3´ Long preignition time
«Z» connected to terminal 15.
With LAL1
«Z» is switched on when start command is given.
With LAL2 / LAL3
«Z» is switched on when «LP» changes over.
 no later than at the end of «t10»
 On completion of «t1», the LAL drives the air damper to the low-fire position via terminal 10
 the low-fire position is defined by the changeover point of auxiliary switch «m» in the actuator
 During the positioning time, the sequence switch maintains its position
 until terminal 8 receives power via «m»
 The motor of the sequence switch is switched to the control section of the LAL
 positioning signals delivered to terminals 8 now have no impact on the further startup sequence and
on subsequent burner operation
TSA Ignition safety time
On completion of «TSA», a flame signal must be present at terminal 22. It must be available until controlled
shutdown occurs
 otherwise, the burner control will initiate lockout and lock itself in the lockout position
t3n Postignition time
 «Z» must be connected to terminal 15
 With short preignition, «Z» remains on until «TSA» has elapsed
 connection to terminal 16