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Building Technologies Basic Documentation LMV27... CC1P7541en
7 Basic unit LMV27 17.12.2018
7.5.2.2. Valve proving via gas pressure switch-min X5-01
Bild 411e/1010
P LT
(Pmin)
P LT
(Pmin)
Figure 2: Valve proving via gas pressure switch-
min
Step 1: t80 – evacuation of test space.
Gas valve on the burner side is opened to bring the test space to
atmospheric pressure.
Step 2: t81 – test time atmospheric pressure.
When the gas has closed, the gas pressure in the test space must
not exceed a certain level.
Step 3: t82 – filling of test space.
Gas valve on the mains side opens to fill the test space.
Step 4: t83 – test time gas pressure.
When the gas valve has closed, the gas pressure in the test space
must not drop below a certain level.
Legend
t80 Evacuation of test space (parameter 242)
t81 Test time atmospheric pressure (parameter 243)
t82 Filling of test space (parameter 244)
t83 Test time gas pressure (parameter 245)
Vx Fuel valve
Pmin Pressure switch-min
P LT Pressure switch – valve proving
Input/output signal 1 (ON)
Input/output signal 0 (OFF)
Input permissible signal 1 (ON) or 0 (OFF)
When making the valve proving test via pressure switch-min-gas, the impact on the
program sequence is as follows (see Sequence diagram G):
a) Valve proving on startup
In place of sampling pressure switch-min-gas (gas shortage test) in phase 22, it is
sampled during the time valve proving is performed at the end of the filling time.
b) Valve proving on shutdown/deactivated
Pressure switch-min-gas is sampled at the end of preignition. For that purpose, a
new phase 39 (Test Pressure switch-min) is introduced and evaluation of gas
shortage is made at the end of the phase (duration of phase = filling time). In
practice, this represents an extension of preignition by the filling time, if valve
proving via pressure switch-min-gas was selected.
The valve proving test can only be made via pressure switch-min-gas, which must be
fitted between the valves. This has an impact on the control sequence (refer to chapter
Sequence diagrams). Valve proving is still activated via parameter 241.
No. Parameter
241
Gas: Execution valve proving
0 = no valve proving
1 = valve proving on startup
2 = valve proving on shutdown
3 = valve proving on startup and shutdown
7.5.2.3. Lockout phase (phase 00)
The relays of the fuel valves and the safety relay (fan) are deenergized, the alarm relay
is energized and lockout takes place. This means that phase 00 can only be quit via a
manual reset. The time of phase 00 is unlimited.
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