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Chapter 4. Explanation of Operation
Example sequence
z Normal operation (Non-recycling gas-fired combustion)
Input AUR890 operation Sequence
codes
Operation of external devices
Power ON When approximately 8 seconds have passed after the power has been
turned on, the 7-segment LED display on the front panel of the AUR890
shows the sequence code [- -].
- -
Burner
operation
switch ON
- - When the burner operation switch is turned
on, the blower starts to operate, and if the
limit and interlock conditions are normal, a
prepurge is done. After the prepurge, the
prepurge completion signal is turned ON.
Blower: operating
Controller
ON
If the prepurge completion signal is ON and the controller is ON, the
internal circuits are checked during the start check.
P 1
Afterward a false ame check is conducted during the ignition wait
time.
P3
If the status is normal, the lockout time begins, relays K1, K2, K3 and K5
turn ON, the ignition transformer starts, the pilot valve begins to open,
and external timer TM1 turns ON.
P4
Ignition transformer : start
Pilot valve : open
(TM1 starts)
When the ame detector detects the pilot burner ame, relay K5 turns
OFF to stop the ignition transformer.
P5
Ignition transformer : continues operation
Pilot valve : remains open
Relay K4 and external relay 103X turn ON.
When the time set for timer TM1 has passed and TM1's contacts have
turned ON, the main valve opens to begin normal combustion.
The FLAME LED (green) on the front panel of the AUR890 lights up.
P8
Ignition transformer : stop
Main valve : open
(103X : ON)
(TM1's contacts : ON)
Burner
operation
switch OFF
When the burner operation switch is turned OFF, relays K1, K2, K3 and
K4 turn o, and the pilot and main valves begin to close.
The FLAME LED (green) on the front panel of the AUR890 turns o.
- - Fuel oil combustion valve : closed
Main valve : closed
Blower : stop
Power OFF When the power is turned OFF, the 7-segment LED display on the front
panel of the AUR890 stops showing the sequence code [- -].
* The AUR890 turns the main valve ON after the standby process for normal combustion. This feature does not allow the main valve to
be turned on immediately after ignition in order to prevent the flame from being blown out. During the standby process for normal
combustion, if the time set for external timer TM1 has passed and the contacts are reversed, the supply of power to the pilot valve and
main valve may be interrupted for a moment.
Whenever a flame is detected just before completion of the time set for external timer TM1, ignition is delayed. Adjust the burner so that
it ignites reliably at least one second before the time set for external timer TM1 passes.
––
P1
–– ––
[Input]
Power supply
[7-segment display]
Limit, Interlock
Stop
Start check
P3
Ignition standby
P4
Lockout timing
P8
Main burner combustion standby
P5
RUN
Stop
[Output]
Ignition transformer
Burner operation switch
Blower
Controller
Flame signal
RESET switch
[LED]
FLAME LED (Green)
Alarm output
Pilot valve
AUR890
Main valve
ALARM LED (Red)
Prepurge time
(external circuit)
Start check + Ignition standby time
Approximately 3 s
Approximately 8 s
Lockout timing time
Main burner combustion standby time
TM1 on delay time
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