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6. OPERATION
NORMAL OPERATION
Inputs
HEAT DEMAND SW OFF
AIR FLOW SW OFF
SAFETY LIMIT SW ON
HEAT DEMAND SW ON
START Pos SW ON
PURGE Pos SW OFF
AIR FLOW SW ON
START Pos SW OFF
PURGE Pos SW ON
PURGE Pos SW OFF
START Pos SW ON
FLAME ON
PURGE & START Pos SW
IGNORED
HEAT DEMAND SW OFF
FLAME OFF
AIR FLOW SW OFF
SAFETY LIMIT SW ON
* For LED indication,
○
means 'off',
* The LEDs are arranged in the following order: Standby, Purge, Ignition, Pilot, Main, Modulate, Flame and Alarm at the left front
side of the DBC2000.
Table 7: Normal operation sequence
Operation of DBC2000 and device
The power supply voltage is applied across Terminal 1 and
2. When no flame signal is present, the combustion airflow
switch is opened (T14=OFF) and safety lockout circuit is
closed (ON), it is possible to start.
The blower is energized (T3). Firing rate goes to PURGE
position. Air flow switch closes (T14=ON) as soon as air flow
is present.
The pre-purge timer starts counting as soon as PURGE
interlock is closed (T16=ON).
After the completion of pre-purge timing, firing rate goes to
START position.
The ignition wait timer starts counting as soon as the START
position interlock is closed (T17=ON).
After completion of the ignition wait timing, the Ignition
sequence starts. The Ignition transformer is energized. The
Intermittent and Interrupted pilot valve outputs are energized
(T5 and T6).
When a flame is detected after the ignition trial has ended
(Safety1), the pilot stabilization time starts.
After completion of the pilot-stabilization time, the Main
valves are energized (T7=ON). Note: Enhanced Model: also
(T12=ON).
The Main trial for ignition takes place (Safety2).
After completion of the main trial time, Interrupted pilot valve
is deenergized (T5=OFF). The Main stabilization time starts.
After completion of the main stabilization time, the firing rate
goes to modulation position and releases control to an
external modulation device.
The intermittent pilot valve and main valves are deenergized
(T6=OFF and T7=OFF). Note: Enhanced Model: also
(T12=OFF). Firing rate moves to PURGE position.
The post-purge timing takes place.
After the completion of the postpurge time, the blower is
deenergized and firing rate moves to START position.
After the air flow switch goes OFF, DBC2000E returns to the
STANDBY condition, waiting for the next heat demand.
●
means 'illuminated'.
12
Indicator LED *
●○○○○○○○
●●○○○○○○
●○●○○○○○
●○●○○○●○
●○○●○○●○
●○○○●○●○
●○○○●○●○
●○○○○●●○
●●○○○○○○
●○○○○○○○
ENI7003R8 KO65 2013
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