Load Output X74 Pin 3; Safe Separation Of Mains Voltage And Extra Low-Voltage; Modulating Operation; 2-Stage Operation - Siemens LMV37.4 Series Basic Documentation

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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
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).

13.2 Modulating operation

Actual value Voltage
Off DC 0 V
Ignition load DC 1 V
Low-fire DC 2 V
High-fire DC 10 V
The values between low-fire and high-fire are interpolated in a linear manner.

13.3 2-stage operation

Actual value Voltage
Off DC 0 V
Stage 1 DC 5 V
Stage 2 DC 10 V
Basic documentation LMV37.4...
13 Load output X74 pin 3
Remarks
No detection of open-circuit
Detection of open-circuit possible
No detection of open-circuit
Recommended setting in
connection with Micro master VSD
Curvepoint Display / output
value
--- Off
P0 10%
P1 20%
P9 100%
Curvepoint Display / output
value
--- Off
P1 P1
P2 P2
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CC1P7546en
20.09.2013