Digital Inputs; Safety Loop X3-04 Pin 1 And 2 - Siemens LMV37.4 Series Basic Documentation

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7.3 Digital inputs

7.3.1 Safety loop X3–04 pin 1 and 2
Input for connection of 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 safety loop includes the following components:
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.
Line voltage (N)
Protective earth (PE)
Power signal for safety loop
Safety loop
(optional pressure switch-max (Pmax))
Figure 9: Safety loop X3-04
For diagnostic purposes, the contacts of the components included in 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) and the numerical
value appears in the error history.
Error Diagnostic
code code
22 0
OFF S
For the input, a repetition counter can be parameterized. Here, it is possible to set the
number of errors permitted until lockout occurs (refer to chapter Repetition counter).
No. Parameter
Repetition limit safety loop
1 = no repetition
215
2...15 = 1...14 number of repetitions
16 = constant repetition
Attention!
In the safety loop, temporarily (<1 s) switching contacts must not be wired
(switch or other)!
Basic documentation LMV37.4...
7 Basic unit
Meaning for the LMV37.4... system
Safety loop/burner flange Open
LMV...
L
5
4
3
2
1
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CC1P7546en
20.09.2013
Si