Observing The Behavior Of The O 2 Trim - Siemens LMV5 Series Technical Instructions

Technical Instructions
Document No. LV5‐1000
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
rich. This offset is dissolved after the O
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Startmode
Observing the Behavior of the O
After the O 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
rates and when transitioning between firing rates.
Expected behavior: the difference between the O
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
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
Control Curve was commissioned.
3. Values less than 50% ‐ less air is needed to achieve O
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
1. Deactivated – the O control was either manually or automatically deactivated
2
2. Locked – the manipulated variable (amount of trim) is being held at the last value
3. LockTStart – O control is waiting to engage after light‐off (waiting for NumberTauSuspend to
2
expire)
Section 6 Page 24 SCC Inc.
, so a setting of ‐2 will offset the O
2
trim becomes active (NumberTauSuspend expires).
2
Trim
2
setpoint is being followed at different firing
2
setpoint and actual value should be slightly more
2
when not transitioning and less than +/‐0.4% O
2
setpoint compared to when O
2
control. Possible values are:
2
HOME
approximately 2% more
2
setpoint compared to when the O
2
LMV Series
2
when
2
2
Control Curve
2