Emergency Operation With Several Load Controller Sources; Manual Control - Siemens LMV37.4 Series Basic Documentation

Building Technologies

9.7.1 Emergency operation with several load controller sources

By making use of the prioritization described above, it is also possible to implement
emergency operation. Should the building automation and control LMV37.4 fail
(provided parameter 148 is set to undefined (--)), the unit switches automatically over to
the external load controller.
A load controller can be connected via analog input or – if existing – via contacts.
No. Parameter
Predefined output in the event of communication breakdown with building
automation
Setting values:
For modulating operation, the setting range is as follows:
0...19.9 = burner off
20...100 = 20...100% burner output (20 = low-fire position)
148
For multistage operation, use the following settings:
0 = burner OFF
P1...P3 = stage 1...stage 3
Invalid = no output predefined by the building automation system in the event
of communication breakdown
Default setting: Invalid

9.7.2 Manual control

If the external load controller via contacts is not used, a simple manual output
adjustment via switch can be implemented by cutting the connection to the load
controller for switching from automatic to manual operation. In that case, the LMV37.4
switches to the external load controller via contact. A switch for Open/Close or stage
2/stage 3 can then be connected to the load controller's terminals.
Basic documentation LMV37.4...
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CC1P7546en
17.12.2018