Limitation Of Ionization Current - Siemens LMS14 User Manual

Additional parameters
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6.38.1 Limitation of ionization current

The Ion curr lim, low [ [4269.1] parameter is used to set the minimum fan speed to a
level that will prevent the burner from shutting down in the event of an ionization current
fault.
If Ion curr lim, low [4269.1] is set to 0, the function is deactivated.
If the ionization current drops below the value of Ion curr lim, low [4269.1], the minimum
speed is set to the current speed.
If the ionization current is still too low, the lower speed limit will be increased to no more
than the Adv wind target speed [4508.1] once every 0.2 seconds.
Assuming the function is activated, this speed defines the lower speed limit for the
speed modulation range in the burner control operating position. Consequently, the
speed limit results in a higher level of modulation and a higher ionization current.
The value of IonCurrLimPosSpdSlope [4398.1] indicates the rate of increase per
second.
If the ionization current exceeds the value of Ion curr lim, low [4269.1] plus the
hysteresis Ion curr lim, change [4270.1], (IonLimit + IonLimitDelta), the lower speed
limit will be reduced every 0.2 seconds. The value of IonCurrLimNegSpdSlope [4397.1]
indicates the drop per second.
Line no. Operating line
Menu: Burner control
[4269.1]
Ion curr lim, low
[4398.1]
IonCurrLimPosSpdSlope
[4270.1]
Ion curr lim, change
[4397.1]
IonCurrLimNegSpdSlope
[4508.1]
Adv wind target speed
This function is not implemented as a class A safety-related function.
The Adv wind target speed [4508.1] parameter is not implemented as a class A safety-
related function either, and the burner control will accept any speed from the set low-
fire value right up to the high-fire value.
User Manual LMS14...
6 The settings in detail
CC1U7471en
28.01.2015