15/25
Building Technologies Division
CC1N7451en
20.11.2017
Startup sequence
A
Start command delivered by «R»
«R» closes the start control loop between terminals 4 and 5
-
The sequence switch starts running
- Only prepurging, power is immediately fed to the fan motor connected to terminal 6
- Pre- and postpurging; on completion of «t7», power is fed to the fan motor or flue gas fan connected
to terminal 7
-
On completion of «t16», the control command to open the air damper is delivered via terminal 9
-
No power is fed to terminal 8 during the positioning time
-
The sequence switch continues its travel only after the air damper has fully opened
t1
Prepurge time with air damper fully open
-
During «t1», the correct functioning of the flame supervision circuit is tested
-
If test is not successful, the burner control will initiate lockout
Shortly after the start of «t1», the air pressure switch must change over from terminal 13 to terminal 14.
Otherwise lockout
Start of air pressure check
At the same time, terminal 14 must be live since the ignition transformer will be powered and the fuel
released via this current path.
On completion of the prepurge time, the burner control will drive the air damper to the low-fire position via
terminal 10, which is determined by the changeover point of auxiliary switch «m». During the positioning
time, the sequence switch stops again. A short time later, the motor of the sequence switch will be switched
to the control section of the burner control. This means that, from now on, positioning signals delivered to
terminal 8 have no impact on the burner’s further startup sequence (and on subsequent burner operation):
t5 Interval
-
On completion of «t5», power is fed to terminal 20; at the same time, control outputs 9...11 and input 8
are galvanically separated from the unit’s control section
The LFL1... is now protected against return voltages from the power control loop
-
The startup sequence of the LFL1… ends with the release of «LR» at terminal 20
-
After a number of idle steps (steps with no change of the contact position), the sequence switch
switches itself off
Direct spark flame burners
TSA Ignition
safety
time
On completion of «TSA», a flame signal must be present at terminal 22. It must not be interrupted until
controlled shutdown takes place
otherwise lockout
t3 Preignition
time
Release of fuel via terminal 18
t4
Interval «BV1 – BV2» or «BV1 - LR»
-
On completion of «t4», terminal 19 is live
-
That powers «BV2» connected to the actuator’s auxiliary switch «v»
