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Building Technologies Basic documentation LMV37.4... CC1P7546en
7 Basic unit LMV37.4 17.12.2018
7.3.7 Gas / oil pressure switch-min, start release gas X5–01
Input for connection of a pressure switch-min for gas or oil: If the plant does not require
a pressure switch-min, a wire link must be fitted between pin 2 and 3.
Gas pressure switch-min
The LMV37.4 enables parameterization of which gas train position the gas pressure
switch-min is mounted on. This also influences the time of the input evaluation.
No. Parameter
236
Gas: Input pressure switch-min
1 = pressure switch-min before fuel valve V1 (default setting)
2 = valve proving (between fuel valve V1 and fuel valve V2) via pressure
switch-min
3 = pressure switch-min after fuel valve V2
In all types of gas trains, the minimum gas pressure is expected from phase 22 in the
default setting (value 1).
If no gas pressure is detected when the maximum time (parameter 214) has elapsed,
the gas shortage program is started (refer to chapter Gas shortage program).
If value 2 is set, the gas shortage check only takes place in phase 39 or in conjunction
with a potential valve proving as part of commissioning.
LMV...
Bild 394en/0517
X5-01
Protective earth (PE)
Pressure switch-min (Pmin)
“L” for pressure switch
Figure 19: Gas pressure switch-min / oil pressure switch-min X5-01
Caution!
The OEM must check to see whether the burner can be operated without
pressure switch-min. This may necessitate a special approval, depending on
the type of application.
No. Parameter
214 Maximum time to start release
During the safety times, the signal received from pressure switch-min is only assessed
after a certain period of time in order to ignore the pressure shocks that occur the
moment the valves open. The time to elapse for signal assessment can be
parameterized.
No. Parameter
229 Gas: Time to respond to pressure faults in the first and second safety time
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