Operating Instructions For TD/TAD4 Dual Fuel Burner
June 13 119 of 165 TD/TAD4 Manual Rev 4
General
Detector and extraneous light test are resumed immediately on completion 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 terminated when the prepurge time «t1» of
the next startup sequence.
The proper functioning of the flame supervision circuit is automatically during each startup
phase of the burner
During the postpurge time «t6», the control contacts for the release checked to ensure they
have not welded.
The built-in unit fuse protects the control contacts against overloads.
Preconditions for start up
Burner control must be reset
Sequence switch must be in its start position - voltage at terminals 4 and 11 present and air
damper closed
End switch «z» for the CLOSED position must feed voltage from terminal 11 to terminal 8
The contacts of control thermostat or pressurestat «W» and other contacts of switching
devices connected between terminal 12 and «LP» must be closed _ e.g. control contact for
the oil preheater’s temperature.
Terminal 4 must be live
The N.C. contact of the air pressure switch must be closed - «LP» test
Start up sequence
A Start command (delivered by «R» for instance)
A-B Startup sequence
B Operating position of the burner
B-C Burner operation (according to the control commands delivered by «R»)
C Controlled shutdown via «R»
C-D Sequence switch travels to start position «A», postpurging
During burner off periods, only control outputs 11 and 12 carry voltage and the air
damper is in its CLOSED position as defined by end switch «z» of the actuator.
Also, in order to perform the detector and extraneous light test, the flame supervision
circuit is live (terminals 22 / 23 and 22 / 24).
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
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