Siemens LMV5 Series Basic Documentation page 250

250/278
Siemens Building Technologies
HVAC Products
18.3 Precontrol
With the measurements made in connection with O
characteristics and behavior of the burner will be acquired. Based on the type of fuel,
the O ratio value, the O
2
the air rate such that the O
conditions do not change, irrespective of burner load.
Calculation of the air rate from the manipulated variable is made such that a manipulated
variable of +10 % offsets an air density change of –10 %.
18.3.1 Calculation of precontrol
Based on the settings for O
characteristics and behavior of the burner. The lambda factor, which is taken into
consideration when calculating the air rate reduction, reflects these values which are
gained from practical experience.
Precontrol can be calculated in 2 different ways:
Parameter:
Type Air Change (like P air, like theory)
The measured lambda factor is also considered when air density
like P air
(temperature pressure) changes. Air pressure and air density have an
impact on the fuel throughput.
The measured lambda factor is not considered when air density
like theory
(temperature pressure) changes. Air pressure and air density have no
impact on the fuel throughput.
Recommendation:
With gas: like P air
With oil: like theory
Basic Documentation LMV51...
18 Addendum 4: LMV52... with O2 trim control and O2 module
setpoint and the standardized value, precontrol calculates
2
setpoint will be reached as long as environmental
2
trim control, the system becomes familiar with the
2
setpoint adjustment, the
2
CC1P7550en
01.10.2003