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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 6 Basic unit 01.12.2009
6.3 Digital inputs
6.3.1 Safety loop X3–04, terminals 1 and 2
Input for the safety loop. When any of the series-connected contacts included in the loop
opens, power supply to the fuel valves, the fan and the ignition equipment is instantly cut.
The following contacts are included in the safety loop:
− External burner switch (ON / OFF)
− Safety limiter / safety pressure limiter (SL / SPL)
− External control thermostat and / or pressurestat, if required
− Water shortage switch
&
Note
- Pressure switch-max (Pmax) when using POC via X5-02
LMV...
Bild 273e /04 09
T6.3 IEC
Safety loop
(optional pressure switch-max (Pmax))
Power signal for safety loop
Protective earth (PE)
Line voltage (N)
STB
Water
shortage
Si
L
1
2
3
4
5
Figure 7: Safety loop X3-04
For diagnostics purposes, the contacts of the safety loop and the burner flange contact
are combined for delivering the safety loop signal. If there is no such signal, the system
initiates safety shutdown in any event.
If with Load controller on, there is no signal from the safety loop (start prevention), error
code 22 is translated to text display OFF S (S = safety loop); the numerical value ap-
pears in the error history.
Error
code
Diagnostic
code
Meaning for the LMV37.4... system
22
OFF S
0 Safety loop / burner flange open
For the input, a repetition counter can be parameterized. Here, it is possible to set the
number of errors that are permitted until lockout occurs (refer to subsection Repetition
counter).
No. Parameter
215
Repetition limit safety loop
1 = no repetition
2...15 = number of repetitions
16 = constant repetition
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