Continuous Fan Operation; Response To Extraneous Light In Standby; Selection Of Fuel; Selection Of Fuel With The Fuel Selector On The Lmv51 - Siemens LMV51 Series Basic Documentation

Continuous fan operation

Response to extraneous
light in standby
Selection of fuel with the
fuel selector on the
LMV51...
Selection of fuel on the
AZL51...

Selection of fuel via bus

Fuel changeover

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For this reason, the PS relieve valve is controlled in Phase 79. This valve ensures that
the air pressure switch is relieved of the pressure produced by the fan so that it can
signal «Air pressure OFF» although the fan motor is running, thus making possible a
functional check of the air pressure switch.
Parameter: NormDirectStart (NormalStart / DirectStart)
For both variants, following applies:
If, during postpurging, there is another demand for heat, or if demand for heat is still
present like in the case of type-of-fuel change, for example, that part of postpurging will
be stopped in Phase 78 in order to accelerate the following startup sequence.
In the case of burners that could be damaged by return heat (e.g. several burners
operating on one combustion chamber), continuous purging can be activated. In that
case, the fan runs in all phases.
To enable the air pressure switch to be tested, a PS relieve valve is required. This valve
is controlled in Phase 21 on burner startup, causing the air pressure to fall, so that the
«Air pressure OFF signal» can be delivered.
Parameter: ContinuousPurge (activated / deactivated)
As a response to extraneous light in the standby phase, it is possible to choose start
prevention or lockout.
Parameter: ReacExtranLight (Lockout / Startblock)

3.2.4 Selection of fuel

The fuel selector is given priority and has 3 positions: INT, GAS and OIL. It is connected
directly to the LMV51... basic unit.
It is possible to switch between oil and gas firing.
If the fuel selector is set to INT, either of the 2 sources can be selected: BMS or
AZL51... .
The type of fuel is selected via the menu on the AZL51... .
The selection is only possible when the fuel selector is set to INT (or when no selector is
connected).
Fuel selection is continuously stored via power-Off, so that a valid fuel selection is
present when power returns.
Selection of fuel via bus (through BMS) is only possible when the fuel selector on the
LMV51... basic unit is set to INT and, on the AZL51..., fuel selection via BMS has been
selected.
Note: Fuel selection via BMS should be cyclically repeated.
There is no definition of priorities between fuel selection via bus and fuel selection via
the AZL51..., which means that the selection made last will be used.
After fuel changeover, the burner control maintains or changes to standby
( ® normal start). Now, a new start is made (provided there is demand for heat), firing
on the selected type of fuel.
If ® direct start has been parameterized, fuel changeover can also take place on
shutdown in Phase 76. The fan will not be switched off.
Basic Documentation LMV51...
3 Burner control
CC1P7550en
29.05.2002