31
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 8:
In a ventilation system the temperature is to be a-
djustable by means of a 0-10 V potentiometer.
The selected temperature must be kept constant, and
the internal PID regulator is to be used. The regulation
required is of the inversed type; this means that when
the temperature goes up, the fan speed increases so
that more air is supplied.
■
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 = Temperature reference 0-50° C, 0-10 V
3 = Temperature transmitter 0-50° C, 4-20 mA
The following must be programmed:
Function:
Parameter no.
Parameter value
Data value no.
Activation of
PID-regulator
101
CLOSED LOOP
[2]
Feedback type
114
CURRENT
[1]
Current signal
413
20-4 mA
[4]
Min. speed
201
10 Hz
Max. speed
202
50 Hz
Regulator range
120
Application-
dependent
Proportional gain
121
Application-
dependent
Integration time
122
Application-
dependent
Ref. independent of
411
Prop w/min
[1]
minimum speed
When the temperature drops, the speed goes down.
The transmitter used is a temperature sensor with a
working range of 0-50°C 4-20 mA. In order to carry
out inverse regulation, VLT 3500 HVAC is program-
med to convert the temperature transmitter signal (4-
20 mA) to 20-4 mA.
The min./max. speed is 10/50 Hz.
2.7 installation examples
