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Building Technologies Basic documentation LMV37.4... CC1P7546en
12 Fan control 17.12.2018
12 Fan control
12.1 Function principle
Optionally, the LMV37.4 can be operated with a VSD or PWM fan.
The activation takes place via a DC 0
…10 V or alternatively via a PWM interface.
For control of the fan’s speed, a safety-related speed feedback signal is required.
With pneumatic fuel-air ratio control, the speed feedback signal is not evaluated as
standard.
It is, however, possible to define additional limit thresholds for supervising the fan speed
during prepurging, ignition and operation.
To facilitate the use of fans with different speed ranges, the fan’s speed is standardized
between 0…100% (up to 14000 rpm is supported as the maximum fan speed).
If fan control is not connected, a load output and, alternatively, a fuel meter output are
available (refer to chapters Load output X74 pin 3 and Fuel meter input X75 pin 1 / X75
pin 2).
LMV...
Bild 332en/1016
X64
VSD X74
M
VSD
Sensor
L
Sensor disk
Actual speed
PWM
or
4
5
3
2
1
4
5
3
2
1
Hall signal
Figure 81: Function principle of VSD
12.2 Activation of VSD/PWM fan
The VSD can be activated in any of the operating modes (parameter 201).
No. Parameter
542
Activation of VSD / PWM fan
0 = deactivated
1 = active
2 = active (no repetition)
Note
For configuration of the analog output when the VSD is activated, refer to chapter
Power output X74 pin 3!
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