Page 20 - Module2_B1_B2_i2_Portrait

Electrical temperature measurement systems
There are three devices used to electrically measure temperature:

 Resistance thermometer
 Thermistor
 Thermocouple

Resistance thermometer (temperature bulb)
Also known as Resistance Temperature Detector (RTD). A temperature change causes a
change in electrical resistance, which is detected using a Wheatstone bridge circuit and
galvanometer. This type of thermometer can measure a very small temperature change
(0.0001°C) and there is a linear relationship between temperature and resistance over the
range 0-100°C.

The Platinum resistance thermometer is commonly used because platinum has a large
temperature coefficient of resistance and resists corrosion.

Advantages

 Accurate

Disadvantages

 Large
 Fragile
 Slow response time

Temperature Sensors 101 RTDs
https://youtu.be/lx3Vzle_h2o

Issue 2 – September 2016 3-10 Total Training Support Ltd
Module 2.3 Thermodynamics © Copyright 2016