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Siemens Building Technologies Basic Documentation LMV51... CC1P7550en
HVAC Products 6 Temperature or pressure controller (internal load controller LC) 01.10.2003
6.9 Output
6.9.1 Output 4...20 mA
This active output serves primarily for covering the current load, e.g. for boiler
sequence control and for display by the BMS (if no bus interface is used).
If a voltage signal is required, it can be delivered by connecting a resistor (maximum
500 Ohm).
Burner OFF 0 % 100 %
I (mA) 4 4 20
Burner OFF Stage 1 Stage 2 Stage 3
I (mA) 4 5 10 15
Tolerance ±5 %
6.10 Multiboiler plants
Boiler sequence control is accomplished with the help of external devices or control
systems (e.g. BACS or PCs).
In principle, there are 2 choices available:
6.10.1 Multiboiler plants by means of an analog input
For that purpose, the LC of the LMV5… has an analog input (X62).
This means that the individual boilers can be
a) released / locked, and
b) operated at the required output
(or set to the required setpoint)
6.10.2 Multiboiler plants by means of a digital interface
For that purpose, BACS terminal X72 on the AZL5… can be used with the help of the
bus interface.
Inputs:
− Controller release / lock
− Predefined setpoint or predefined load
Outputs:
− Actual value
− Controller ON / OFF
− Manipulated variable multistage / modulating
− Error messages
For more detailed information, refer to → section 7.2.2 Connection to superposed
systems.
Output, modulating
Output, multistage
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