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Siemens Building Technologies Basic Documentation LMV5... CC1P7550en
HVAC Products 6 Temperature or pressure controller (internal load controller LC) 13.08.2004
6.4.2 Modulating control
When selecting «Gas» as a fuel, the LMV5... will automatically operate in modulating
mode. For that reason, no parameterization is required when firing on gas.
When selecting «Oil» as a fuel, the operating mode is to be set to «Modulating» - if re-
quired - using parameter «Operation Mode» of the electronic fuel / air ratio control sys-
tem.
In this operating mode, the LC calculates the manipulated variable by means of a PID
algorithm, depending on the control differential.
Example 1: The load is so small that the controller must switch to ON / OFF mode.
Setpoint Actual value
7550f07E/0502
R=ON
Y=OPEN
Y=CLOSED
W
SD_ModOff
SD_ModOn
Example 2: The load is greater than the amount of heat produced by the burner under
part load conditions, thus enabling correct modulating operation.
Setpoint Actual value
7550f08E/0502
R=ON
Y=OPEN
Y=CLOSED
W
SD_ModOff
SD_ModOn
Parameters:
Proportional band: P-Part (Xp) (2...500 %) of the parameterized measurement range
Integral action time: I-Part (Tn) (0...2000 s) 0 = no I-part
Derivative action time: D-Part (Tv) (0...1000 s) 0 = no D-part
The PID parameters can be manually set to any value of the above setting ranges, or a
triple value from the standard values described below can be activated (and further ed-
ited it required).
Standard values:
The controller’s memory contains 5 standard parameter sets.
If required, one of these 5 PID triple values can be copied to the storage locations for
the actual values so that it becomes active.
PID standard values for the following applications:
Parameter: Standardparam (very fast / fast / normal / slow / very slow)
General
Function diagrams
Control parameters
Manual setting of the
control parameters
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