Siemens LMV 5 Series, Технические инструкции, Страница: 193 / 374

LMV Series Technical Instructions
Document No. LV5 ‐ 1000
SCC Inc. Page 21 Section 6
O2MaxManVariable and O2MinManVariable – These parameters set how much the O
2
system can trim
in an attempt to achieve the O
2
setpoint ‐ essentially the trim limits for the O
2
system.
O2MaxManVariable sets how much the system can increase the air rate. Likewise, O2MinManVariable
sets how much the system can decrease the air rate.
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Control Param
These trim limits must be set so that the O
2
system can achieve the O
2
setpoint. However, the limits
should not be set in a way that allows the burner to run at an unsafe fuel ‐ air ratio.
Ideally, the O
2
trim system must compensate for two main environmental conditions. These conditions
are ambient air temperature and barometric pressure. Figure 6 ‐ 8 illustrates how much the manipulated
variable needs to change to compensate for these environmental conditions. The chart in Figure 6 ‐ 8
and the example in Figure 6 ‐ 9 serve as a guideline for setting the O2MaxManVariable and
O2MinManVariable parameters.
Figure 6 ‐ 8: Theoretical Change of the Manipulated Variable with Changes in Ambient Temperature
and Pressure
When the O
2
Control Curve is commissioned, all burners will be at (0, 0) on the chart, where the X ‐ axis
and Y ‐ axis cross. As air temperature and barometric pressure change from the air temperature and
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