VLT
®
Series 3500
42
Example 8:
In a ventilation system the temperature is to be adjusted
by means of a 0 to 10 V potentiometer. The selected
temperature must be kept constant, and the internal PID
controller in the drive is to be used. The regulation
required is of the inverse type; this means that when the
temperature goes up, the fan speed increases so that
more air is supplied.
Function:
Parameter #
Parameter Value
Data Value #
Safety interlock
003
KEY HOA w. stp
[1]
Activation of PID-regulator
101
CLOSED LOOP
[2]
Feedback type
114
CURRENT
[1]
Regulator range
120
Application dependent
Proportional gain
121
Application dependent
Integration time
122
Application dependent
Minimum speed
201
10 Hz
Maximum speed
202
60 Hz
Current signal
413
20 to 4 mA
[4]
The transmitter used is a temperature sensor with a
working range of 32 to 120
°
F, 4 to 20 mA. In order to
carry out inverse regulation, the drive is programmed to
convert the temperature transmitter signal (4 to 20 mA)
to 20 to 4 mA.
The minimum and maximum speeds are 10 and 60 Hz.
NOTE:
A shield for control wires is to be connected in
accordance with the installation instructions.
All settings are based on factory settings.
Be sure to check the motor data settings (parameters
104, 105 and 107, or the Quick Setup menu items 1, 2
and 3). They must be set based upon the actual motor
used.
1 = Start/Stop
2 = Temperature reference 32 to 120
°
F, 0 to 10 V
3 = Temperature transmitter 32 to 120
°
F, 4 to 20 mA
External safety interlocks can be connected between
terminals 12 and 27.
The following must be programmed:
