Siemens LMV37.400A2 - Electronic Air-Fuel Ratio Control; General Principles of Air-Fuel Ratio Control; Actuator Behavior Outside Operation

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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 9 Electronic air-fuel ratio control 01.12.2009
9 Electronic air-fuel ratio control
9.1 General
Electronic air-fuel ratio control is used for controlling the burner’s actuators depending
on burner output. It is possible to connect 2 actuators and, optionally, one VSD.
Resolution is 0.1° with the actuators and 0.1% with the VSD. Output can be regulated in
increments of 0.1% in modulating mode and with a maximum of 3-stages in multistage
mode.
To reduce the amount of electric power required for the actuators, they are never oper-
ated simultaneously, but in successive order, or alternately.
9.2 Behavior outside operation
Outside the running position, the actuators approach the different positions in succes-
sive order.
The program phase determines the position to be approached.
9.2.1 Running speed
The actuators’ running speed is fixed at 5 seconds for a positioning angle of 90°.
The ramp speed of the VSD can be adjusted separately for higher and lower speeds.
No. Parameter
522 Ramp up
523 Ramp down
The setting also applies to the running position (refer to subsection
Running position).
9.2.2 No-load position
This position is approached in the
Home run (10), Standby (12) and Lockout position
(00) phases.
The position can be set via the following parameters:
Parameter Actuator
501.00 No-load position fuel actuator
502.00 No-load position air actuator
503.00 No-load speed VSD