Example Of Process Pid Control - Danfoss VLT FC 360 Design Manual

Product Overview

2.5.4 Example of Process PID Control

Illustration 2.14 is an example of a Process PID Control
used in a ventilation system:
Cold air
W n °C
Illustration 2.14 Process PID Control in a Ventilation System
In a ventilation system, the temperature is to be settable
from - 5 to 35 °C with a potentiometer of 0-10 V. The set
temperature must be kept constant, for which purpose the
Process Control is to be used.
The control is of the inverse type, which means that when
the temperature increases, the ventilation speed is
increased as well, so as to generate more air. When the
temperature drops, the speed is reduced. The transmitter
used is a temperature sensor with a working range of -10
to 40 °C, 4-20 mA. Min./Max. speed 300/1500 RPM.
®
VLT AutomationDrive FC 360 Design Guide
L1
L2
L3
N
PE
100kW
Heat
generating
process
Temperature
transmitter
Illustration 2.15 Two-wire Transmitter
®
MG06B202 - VLT is a registered Danfoss trademark
F1
12
91 92 93 95
27
L1 L2 L3 PE
18
50
53
55
U V W PE
54
96 97 98 99
M
3
1. Start/Stop via switch connected to terminal 18.
2. Temperature reference via potentiometer (-5 to
35 °C, 0-10 V DC) connected to terminal 53.
3. Temperature feedback via transmitter (-10 to 40
°C, 4-20 mA) connected to terminal 54.
2
Transmitter
29
2