Danfoss FC 102 Design Manual page 41

Introduction to VLT® HVAC D...
reference are added to produce the total external
reference. The external reference, the preset reference or
the sum of the 2 can be selected to be the active
reference. Finally, this reference can by be scaled using
3-14 Preset Relative Reference.
The scaled reference is calculated as follows:
Y
Reference = X + X ×
100
Where X is the external reference, the preset reference or
the sum of these and Y is 3-14 Preset Relative Reference in
[%].
If Y, 3-14 Preset Relative Reference is set to 0%, the
reference is affected by the scaling.
2.8.10 Example of Closed Loop PID Control
Cold air
W n °C
Illustration 2.30 Closed Loop Control for a Ventilation System
In a ventilation system, the temperature is to be
maintained at a constant value. The desired temperature is
set between -5 and +35 °C using a 0-10 V potentiometer.
Because this is a cooling application, if the temperature is
above the set-point value, the speed of the fan must be
increased to provide more cooling air flow. The
temperature sensor has a range of -10 to +40 °C and uses
a 2-wire transmitter to provide a 4-20 mA signal. The
output frequency range of the frequency converter is 10 to
50 Hz.
1. Start/Stop via switch connected between
terminals 12 (+24 V) and 18.
2. Temperature reference via a potentiometer (-5 to
+35 °C, 0 to 10 V) connected to terminals 50 (+10
V), 53 (input) and 55 (common).
3. Temperature feedback via transmitter (-10 to 40
°C, 4-20 mA) connected to terminal 54. Switch
S202 behind the LCP set to ON (current input).
MG11BC02
Design Guide
L1
L2
L3
N
PE
100kW
Heat
generating
process
Illustration 2.31 Example of Closed Loop PID Control
Temperature
transmitter
2.8.11 Programming Order
NOTICE
In this example, it is assumed that an induction motor is
used, i.e. that 1-10 Motor Construction = [0] Asynchron.
Function
1) Make sure the motor runs properly. Do the following:
Set the motor parameters
using nameplate data.
Run Automatic Motor
Adaptation.
2) Check that the motor is running in the right direction.
Run Motor Rotation
Check.
3) Make sure the frequency converter limits are set to safe
values
Check that the ramp
settings are within
capabilities of the
frequency converter and
allowed application
operating specifications.
Prohibit the motor from
reversing (if necessary)
Danfoss A/S © Rev. 06/2014 All rights reserved.
F1
12
91 92 93 95
37
L1 L2 L3 PE
18
50
53
55
U V W PE
54
96 97 98 99
M
3
Paramete
r
1-2*
1-29
1-28
3-41
3-42
4-10
5 kΩ
Transmitter
Setting
As specified by motor
name plate
[1] Enable complete AMA
and then run the AMA
function.
If the motor runs in the
wrong direction, remove
power temporarily and
reverse 2 of the motor
phases.
60 s
60 s
Depends on motor/load
size!
Also active in Hand
mode.
[0] Clockwise
39
2 2