Siemens LME73 - Digital Input; Safety Loop Terminal X3-04 Pin 1 and 2; Input for External Controller (ON;OFF) Terminal X5-03 Pin 1

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Building Technologies Basic Documentation LME7... CC1P7105en
10 Basic unit 17.04.2018
10.2 Digital input
10.2.1 Safety Loop terminal 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 (SB / SDB)
, External control thermostat and/or pressurestat, if required
, Water shortage switch
LME...
7105z15e/1111
Safety loop
(optional pressure switch-max (Pmax))
Supply signal for safety loop
Protective earth (PE)
Power supply (N)
S
T
B
W
a
t
e
r
s
h
o
r
t
a
g
e
Si
L
1
2
3
4
5
Figure 12: Safety Loop terminal X3-04
For diagnostic purposes, the contacts of the components included in the safety loop 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/OFF) there is no signal from the safety loop (start
prevention), error code LOC 22 is translated to text display.
10.2.2 Input for external controller (ON/OFF) terminal X5–03 pin 1
When the external control loop is closed, the internal input message Heat request is
generated.
A heat request exists when the external controller signal is pending and, depending on
the configuration, a load controller calls for heat
When there are no more requests for heat, the burner shuts down. The fuel valves are
closed, either immediately when the timer has elapsed, or when the low-fire position is
reached, depending on the parameter settings
Β
Note
Burner startup takes place only when this contact is closed.
LME...
7105z18e/1211
X
5
-
0
3
External load controller (ON/OFF)
External load controller OPEN/stage 2
“L” for controller control
ON/OFF
1
Figure 13: Inputs for external load controller ON/OFF terminal X5-03