Laars MagnaTherm HTD Series, Инструкция по установке и эксплуатации

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LAARS Heating Systems
Page 106
Table 23. BIC Status and LMV Status
10.E Operation
This unit utilizes three (3) separate controllers to
manage system functions, burner management and air/
fuel ratio control:
- Burner Integrated Control (BIC)
- Linkageless Modulating Valve (LMV)
- Oxygen Controller (O2C)
These controllers communicate with each other
via voltage and current signals, and serial digital
communication using Modbus protocol. The BIC also
communicates with the touch screen display and all
user inputs.
When there is a call for heat the BIC will provide an
enable signal to the LMV which tells the LMV to initiate
burner operation. For this signal to be sent and acted
upon, the safety circuit must be satisfied and both
controllers must be in standby mode.
The system pressure sensors, which measure the
overall system pressure drop must also read zero in
order for the Safety Status to be verified.
The Safety Circuit status can be verified on the
Services/Digital I/O screen. Once the LMV is enabled it
will proceed through the startup states listed in Table 23
until it gets to Run. Once in Run, the LMV will receive
a firing rate demand from the BIC and position the fuel
and air dampers and blower speed accordingly.
After the burner has been on for two (2) minutes
the oxygen trim loop will be enabled and the blower
speed will be adjusted to maintain the preset oxygen
concentration in the boiler exhaust.
If a pilot flame is not detected during the “verify pilot”
stage, the LMV will skip to postpurge and then back
to Blower On to retry. Four attempts will be made
before the LMV will Lockout. Once in Lockout, a hard
reset is required by pressing the Reset Button on the
touchscreen.
If the main flame is not detected during the “Verify
Main Burner” stage, the LMV will skip to postpurge and
then back to Blower On to retry the pilot and then main
burner ignition. Only one (1) retry will be attempted
during a given call for heat. If main flame ignition does
not occur on the second attempt, the LMV will lockout.
If the call for heat is satisfied normally, the BIC will
remove the enable signal and the LMV will de-energize
the fuel valves and enter postpurge. Any time there
is an interruption of the BIC safety circuit, both the
LMV enable signal and LMV safety loop signal will be
removed, triggering a burner shutdown. Along with
the circuit components identified in the System Ladder
Logic, the system differential pressure is continuously
monitored while the burner is in operation.
If the system differential pressure exceeds it’s setting,
the Safety Status will be disabled shutting down the
burner. The cause of the safety shutdown will be
displayed on the touchscreen. A manual reset
is required to restart the system once the fault
condition has been corrected.
BIC Status LMV States
Phase Phase
Standy 12 Standby
Call For Heat
LMV Enable
22 Blower On
24
Component Calibration
Pressure Transmitter Verification 30 Prepurge
36 Move to Ignition Position
38 Igniter On
Read (via Modbus) ACC State 40 Pilot On
and Display at
Touchscreen
42 Verify Pilot
50 Main Fuel On
52 Pilot Off/Verify Main Burn
60 Run
Fan Speed Governed by
Controller Demand Signal
End Call for Heat
LMV Disable
70 Post Purge
74 Shutdown
Standby Standby