Siemens LMV 5 Series, Технические инструкции, Страница: 192 / 374

Technical Instructions LMV Series
Document No. LV5 ‐ 1000
Section 6 Page 20 SCC Inc.
Post Commissioning Tuning
After the O
2
curves have been set up according to the procedures above, some additional burner / boiler
specific tuning may be necessary to keep the O
2
trim operating properly. When and how to use these
tuning parameters is discussed below.
LoadCtrlSuspend ‐ This sets the load change that is necessary to make the O
2
trim transition from active
O
2
trim to pre ‐ control. Many factors influence the setting of this parameter.
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Control Param
Higher settings (more active trim, less pre ‐ control) can help the O
2
trim stay close to setpoint in the
following situations:
1. The O
2
Control Curve is relatively flat from low fire to high fire (varies less than 0.5% O
2
)
2. The modulation ramp time is slow ( OperatRampMod is set to 60 seconds or more)
3. The delay time (Tau time) of the boiler is relatively fast ( Tau Low ‐ Fire is set to 7 seconds or less)
Lower settings (less active trim, more pre ‐ control) can help the O
2
trim stay close to setpoint in the
following situations:
1. The O
2
Control Curve slopes from low fire to high fire (varies more than 0.5% O
2
)
2. The modulation ramp time is fast ( OperatRampMod is set to 30 seconds)
3. The delay time (Tau time) of the boiler is slow ( Tau Low ‐ Fire is set for more than 7 seconds)
O2TrimBehavior ‐ If parameter Startmode is set to “standard”, this setting controls how the O
2
trim
responds if the measured O
2
value starts to move away from the O
2
setpoint significantly.
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Control Param
1. A setting of “ForcedAirAdd” will help if deactivations are due to the rich limit (O
2
alarm) since air will
be added more aggressively.
2. A setting of “ForcedAirRed” will help if deactivations are due to the lean limit ( O2 MaxValue ) since
air will be subtracted more aggressively.
3. A setting of “symmetric” is used when the rich limit (O
2
alarm) and the lean limit ( O2 MaxValue ) are
relatively close together, and an aggressive correction in one direction might cause a deactivation
due to the other limit.
NOTE: On an LMV52.440 with the StartMode set to something other than “standard”, the setting of
O2TrimBehavior has no effect.
O2ModOffset ‐ During a load change when the pre ‐ control becomes active (see LoadCtrlSuspend ), this
will temporarily add more air beyond what is prescribed by the Lambda Factor. Increasing this setting
can help with rich limit (O
2
alarm) deactivations during modulation, but this parameter should not be
used as a substitute for proper O
2
trim commissioning procedures.
Menu path: Params & Display > O2Contr/Alarm > Gas Settings > Control Param
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