Load Output X74 Pin 3; Safe Separation Of Mains Voltage And Extra Low-Voltage - Siemens LMV37.4 Series Basic Documentation


148/267
Building Technologies

13 Load output X74 pin 3

The load output is only available as an alternative to VSD control. If the VSD is
deactivated, the output for the VSD delivers the current burner output. The analog
output is a voltage output and – using parameter 645 – can be switched between DC
0...10 V, DC 2...10 V and DC 0/2...10 V.
Parameter 645 Voltage range
0 DC 0...10 V
1 DC 2...10 V
2 DC 0/2...10 V
Note
When changing the analog output configuration from DC 0...10 V to DC 2...10 V or
DC 0/2...10 V, the voltage values with modulating, 2-stage and 3-stage operation
change (refer to chapter Modulating operation, chapter 2-stage operation and chapter
3-stage operation).
Conversion: New value = (initial value * 0.8) + 2
Initially 2 V  (2 * 0.8) + 2 = 3.6 V
Example:
Initially 5 V  (5 * 0.8) + 2 = 6 V
No. Parameter
Configuration of analog output
0 = DC 0...10 V
645
1 = DC 2...10 V
2 = DC 0/2...10 V
13.1 Safe separation of mains voltage and extra
low-voltage
Caution!
The load output is designed for SELV or PELV (refer to chapter Electrical
connection of the LMV37.4).
For this reason, strict separation from the mains voltage side must be ensured!
This necessitates power supply by an external power pack (X74 pin 1, X74 pin 2).
LMV...
5
4
Power output
3
GND
2
24 V external
1
Bild 433en/0916
Figure 92: Power output
Basic documentation LMV37.4...
13 Load output X74 pin 3
Remarks
No detection of line interruption
Detection of line interruption
possible
No detection of line interruption.
Recommended setting in
connection with Micromaster VSD
CC1P7546en
17.12.2018