Modulating Control - Siemens LMV50 Series Manual

General
Function diagrams
Building Technologies

7.4.2 Modulating control

When selecting Gas, the LMV5 will automatically operate in modulating mode. For this
reason, parameterization is not required when firing on gas.
When selecting Oil, the operating mode is to be set to modulating, if required, using
parameter Operation Mode of the electronic fuel-air ratio control system.
In this operation mode, the load controller calculates the manipulated variable by
means of a PID algorithm, depending on the control deviation.
Example 1: The load is very small so that the controller must switch to ON/OFF mode.
SD_ModOff
W
SD_ModOn
R=ON
Y=OPEN
Y=CLOSED
Figure 53: Modulating control – function diagram example 1
Example 2: The load is greater than the amount of heat produced by the burner under
low-fire conditions, thus enabling correct modulating operation.
SD_ModOff
W
SD_ModOn
R=ON
Y=OPEN
Y=CLOSED
Figure 54: Modulating control – function diagram example 2
Basic Documentation LMV5...
7 Boiler controller / load controller
Setpoint Actual value
Setpoint Actual value
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22.05.2018