Hello, friends, I hope you all are doing great. In today’s tutorial, we will discuss the difference between Thermocouples & thermistors. thermocouple has a detecting element is the voltage which induces into a different metallic plate. While in the case of thermistors, the temperature-detecting element is resistance. Both these components are devices used to detect the temperature with different working operations. If the temperature varies the resistance of the material used in the thermistor varies. For a temperature change, voltage is produced among the electrodes of different substances in the thermocouples.
In today’s post, we will have a detailed look at both thermocouples and thermistors with the detailed and find their difference. So let’s get started with thermocouple vs thermistor.
Difference Between Thermocouple & Thermistor
Thermocouple
- There is 2 different electric connections are used in thermocouples to make electrical connection
- It works on the feedback effect to find the voltage after measuring the temperature
- They are called temperate sensors
- Normally available devices are less costly and used to measure different values of temperatures.
- They work on self-excitation and do not need separate supplies.
- They have some drawbacks in that they are less accurate
- They are employed in different industries and measure tempered at kilns and steam coming from the turbine
- They also work in homes in thermostats
- Its temperature measurement range is from -50 centigrade to 250 centigrade.
- The response time of this module is 0.12 to 10s.
- When it is used to find temperature voltage is induced between the electrons of thermocouples which are of different materials.
- The materials used for the construction of thermocouples are Copper, iron, Constantan, Chromel, Alloys of metals like Chrome, etc
- It provides higher accuracy than the thermistor.
- In instruments like ovens, refrigerators, fire alarms it uses.
- Its common applications are temperature regulation, temperature calculation, and temperature compensation.
- The characteristic curve of a thermocouple is non-linear in case of a negative temperature coefficient.
- Its price is larger than the thermistor.
Definition of Thermocouple
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The thermocouple is a sensor that measures temperature. It comes with two different metals, connected at one end point. When the junction of two meals is heated or cooled, voltage is produced that can correlated with temperature.
Thermocouple Features
- Thermocouples are rugged instruments that are immune to shock vibration and are best for use in hazardous conditions. As it is small and comes with less thermal capacity, responds fastly to temperature variation for sensing junction is exposed.
Thermistor
- It is a heat-sensitive device whose resistance value varies with the change in temperature.
- It is manufactured with semiconductor materials.
- The detective element of the thermistor is resistance.
- It is constructed with Manganese, nickel or cobalt oxides, and semiconductor material.
- It provides high accuracy. So we can measure a small change in temperature due to the negative temperature coefficient.
- It provides a fast response time.
- Its accuracy is less than the thermocouple.
- Its measurable temperature range is two hundred centigrade to twelve fifty centigrade.
- Its response time is 0.2 to ten seconds
- The characteristic curve is linear.
- It is used to find the temperature of devices used in a home.
- Its measured temperature range is -60 to 15 centigrade.
- It has two types NTC and PTC NTC resistance drops with temperature rise and in PTC resistance rises with temperature rise.
- PTC used to control overcurrent and used in a series combination
- It is used in industries to find the temperature of machines.
- Its common applications are measurement and regulation of temperature.
Definition of Thermistor
- A thermistor is a semiconductor resistor that has resistance based on temperature as compared to standard resistors. Word thermistor is a portmanteau of thermal and resistor. Thermistors are defined based on their conduction models.
Thermistors Features
- its resistance temperature coefficient is ten to 100 times higher than metal, and detects temperature variations 10-6 °C;
- Normally temperature devices are best for -55 °C ～ 315 °C, high-temperature devices are best for temperatures higher than 315 °C (currently up to 2000 °C), and low-temperature devices are best for -273 °C to -55 °C.
- It can measure the temperature of voids, cavities, and blood vessels in living bodies that are not measured with thermometers;
- We can select resistance values 0.1 to 100kΩ;
- It can easily processed in complicated shapes and generated in large number
6. Good stability and strong overload capacity.
Different Thermocouple Types and Their Applications
Different types of thermocouples exist and each type comes with its own features and temperature range.
Type K Thermocouple:
- This thermocouple is created with chrome and alumel and mostly used thermocouple. Its temperature range is -200°C to 1,372°C and is best for industrial processes, HVAC systems, and power plants.
Type J Thermocouple:
- It is made with iron and constantan and comes with a temperature range of -40°C to 750°C. It is used for food processing, ovens, and furnaces.
Type T Thermocouple:
- It is created with copper and constantan and the temperature range is -200°C to 350°C. It is used in low-temperature applications like refrigeration and cryogenics.
Type E Thermocouple:
- It is created with chrome and constantan and the different range is -200°C to 900°C. It is used in automotive, petrochemical, and aerospace industries.
thermistor vs thermocouple
| Features | Thermocouple | Thermistor |
|---|---|---|
| Definition | It is used for measuring temperature | It is a thermal resistor whose resistance varies with the temperature. |
| Material | Constantan, Chromel, Copper, iron, Alloys of metals like Chrome, chromium etc | Manganese, nickel, |
| Accuracy | High | Very Low |
| Temperature | -50°C to 250°C | -200°C to 1250°C |
| Response Time | 0.12 to 10 Seconds | 0.2 to 10 seconds |
| Characteristic Curve | Non-linear | Linear |
| Cost | Costly | Low cost |
| Uses | ovens, refrigerators, fire alarms, etc. | Industries. |
| Applications | temperature control, Measure temperature, thermal conductivity, temperature compensation, etc. | Measure and control temperature |
Read also:
- Difference Between RTD and Thermocouple
- Difference Between RTD & Thermistor
- What is a 10k Resistor? Explain 10k Ohm Resistor Color Code
- What is Bimetallic Thermometer? – Definition, Working, Construction, Spiral & Helix Strip Thermometer
- Introduction to Sensors and Transducers
- What is Hot Wire Anemometer? – Definition, Working Principle, Construction
FAQs
What is the difference between thermocouple and thermistor?
- NTC thermistors and thermocouples are operated in different ranges and are best for different uses. NTC thermistors work in range of -50 to 250 °C and thermocouples working range is -200 °C to 1750 °C
What is the difference between a thermistor and a thermopile?
- Thermistors and thermocouples are the conventional components for temperature measurement and they need contact with the bodies that to measured. The difference is that the thermistor measures absolute temperature and thermocouples and thermopiles measure relative temperatures,
What are the disadvantages of thermistors?
- The main drawback is that it is not accurate, thatn thermocouples or resistance thermometers. But thermistors are non-linear. They are nonlinear for high temperatures and best to use for measurements of less than 100°C.
What is the difference between a thermocouple and thermometer?
- Thermometers is easy to use and best for temperature measurements. Thermocouples is complicated and different ranges are used for high high-precision needs.
What is the function of thermistor?
- Thermistors are used in different industrial uses to measure the temperature of surfaces, liquids, and ambient gasses.
That is all about the difference between thermocouples and thermistors. I tried my level best to make simple this post for you. If you have any queries ask in the comments. Thanks for reading. Have a good day.
