Siemens LMV 5 Series, Technical Instructions, Page: 196 / 374

Technical Instructions LMV Series
Document No. LV5 ‐ 1000
Section 6 Page 24 SCC Inc.
O2InitOffset ‐ For the other three start modes other than "standard", this is a rich or lean bias that is
applied to the temperature compensation. Negative values ( ‐ 2 to ‐ 0.1) will bias the temperature
compensation more rich, and positive values (0.1 to 2) will bias the temperature compensation more
lean. Note that the units on this are %O
2
, so a setting of ‐ 2 will offset the O
2
approximately 2% more
rich. This offset is dissolved after the O
2
trim becomes active ( NumberTauSuspend expires).
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Startmode
Observing the Behavior of the O
2
Trim
After the O
2
curves are commissioned and post commissioning tuning is done, the behavior of the O
2
trim can be observed and evaluated to determine if further tuning is necessary.
Current O2 Value and O2 Setpoint
Menu path: Operation > O2 Module
Parameters can be toggled between to see how well the O
2
setpoint is being followed at different firing
rates and when transitioning between firing rates.
Expected behavior: the difference between the O
2
setpoint and actual value should be slightly more
when the burner is transitioning between firing rates and less when not transitioning. As a guideline,
the difference should be less than +/ ‐ 0.2% O
2
when not transitioning and less than +/ ‐ 0.4% O
2
when
transitioning.
ManVar O2 Ctrl
Menu path: Params & Display > O2 Contr/Alarm > Process Data
This parameter shows the amount of trim. The value shown is defined below:
1. A value of 50% indicates no trimming.
2. Values greater than 50% ‐ more air is needed to achieve O
2
setpoint compared to when the O
2
Control Curve was commissioned.
3. Values less than 50% ‐ less air is needed to achieve O
2
setpoint compared to when O
2
Control Curve
was commissioned.
Expected behavior: should stay relatively consistent from low fire to high fire. Should change with
external changes such as combustion air temperature, barometric pressure, draft, heating value of fuel,
air filters becoming dirty, etc.
State O2 Ctrl
Menu path: Params & Display > O2 Contr/Alarm > Process Data
This parameters identifies the state of the O
2
control. Possible values are:
1. Deactivated – the O
2
control was either manually or automatically deactivated
2. Locked – the manipulated variable (amount of trim) is being held at the last value
3. LockTStart – O
2
control is waiting to engage after light ‐ off (waiting for NumberTauSuspend to
expire)
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