Siemens LMV37.400A2 - VSD Control via Interface X74.3; PWM Fan Control via Interface X64.3; Safe Separation for Fan Control

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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 11 Fan control 01.12.2009
11.3 VSD control X74.3
The VSD is controlled via a voltage interface (refer to chapter
Power output X74.3)!
Depending on the type of VSD used, a release contact is required. This contact can be
controlled via the fan motor contactor. To enable the VSD to bring the fan motor’s speed
to the correct no-load speed, the motor contactor’s drop out delay time must be about
25 seconds.
Example:
K1
22
9
5
21
3
4
+24 V
+
Setpoint 0...10 V
Siemens Micromaster 440
K1
28
Figure 46: Connection of VSD to the LMV37.4...
11.4 PWM fan control X64.3
The PWM fan is controlled via PWM voltage interface X64.3.
Caution!
The use of PWM fans is only possible in connection with pneumatic ratio con-
trol!
11.5 Safe separation of mains voltage and protec-
tive extra low-voltage
Caution!
All inputs and outputs of PWM fan control are designed for use with protective
extra low-voltage. For this reason, strict separation from the mains voltage side
must be ensured!
This necessitates an external power supply by the VSD or an external power pack
(X74.1, X74.2).
&
Note
Power must also be supplied via X74.1/2 in the case a PWM fan is used.