25
VLT
®
3500 HVAC
MG.35.B1.02 – VLT is a registered Danfoss trademark
Section 1Section 1Section 1Section 1Section 1
Section 2Section 2Section 2Section 2Section 2
Section 3Section 3Section 3Section 3Section 3
Section 4Section 4Section 4Section 4Section 4
Example 2:
In a ventilating system an option of reversing the fan
in the case of fire is desired, so that flue gases can be
removed or fresh air blown in.
The control signal used is 4-20 mA, corresponding to
0-100% motor speed, typically 0-50 Hz.
■
Information is desired on the output frequency, i.e. an
expression of the motor speed. The analogue output
4-20 mA is used. 4 mA corresponds to 0 Hz and 20
mA corresponds to the max. output frequency,
normally 50 Hz.
NB!:
NB!:
NB!:
NB!:
NB!:
Screen for control cables must be connected
as described in the chapter on EMC-correct
installation.
All settings are based on factory settings; however,
motor data settings (parameters 104, 105 and 107)
(or the Quick Set-up menu items 1, 2 and 3) are to be
adjusted to the motor connected.
1 = Start/Stop
2 = Reversing
3 = 4-20 mA
4 = 4-20 mA
The following must be programmed:
Function
Parameter no.
Parameter value
Data value no.
0-f
MAX
407
f
MAX
= 4-20 mA
[20]
Reference
413
4-20 mA
[2]
2.7 installation examples
