文档介绍：INSTRUMENTATION AND CONTROL
TUTORIAL 2 – SENSORS AND PRIMARY TRANSDUCERS
This tutorial provides an overview of instrument sensors used in process and automatic
control. It is useful to anyone studying measurement systems and instrumentation but it is
provided mainly in support of the EC module D227 – Control System Engineering. This
tutorial is mainly descriptive.
Control is a broad concept and the following might apply to an automated system such as
a robot or to a process control system such as a pneumatic valve controlling the flow of
steam in a pipe.
pletion of this tutorial, you should be able to do the following.
· Explain a basic measurement system.
· Explain the basic working principles of a variety of temperature sensors.
· Explain the basic working principles of a variety of pressure sensors.
· Explain the basic working principles of a variety of speed transducers.
· Explain the basic working principles of a variety of flow meters.
· Explain the basic working principles of a variety of force gauges.
· Explain the basic working principles of a variety of displacement gauges.
· Explain the basic working principles of a variety of level (depth) gauges.
· Explain in some detail the theory and use of strain gauges.
In order plete the theoretical part of this tutorial, you must be familiar with basic
mechanical and electrical science.
Ó 1
1. INTRODUCTION
A basic instrument system consists of three elements:
i SENSOR or INPUT DEVICE
ii SIGNAL PROCESSOR
iii RECEIVER or OUTPUT DEVICE
This tutorial is devoted to input devices but you can never separate it from the rest of the system as in many cases
they are all integral (. a mechanical pressure gauge incorporates all of these elements). A block diagram of a
basic system is shown but they are usually plex.
Figure 1
Most modern analogue equipment works on the foll