Thermocouple vs Thermistor: How Are These Words Connected
The phrases “thermocouple” and “thermistor” are presumably familiar to you if you work with temperature measurement. Despite the fact that each of these instruments detects temperature, their design, functionality, and intended uses are very unlike. The distinctions between thermocouples and thermistors as well as their connections will be discussed in this article. So let’s get started with thermistor vs thermocouple
Introduction
Numerous applications in the fields of industry, science, and engineering depend on accurate temperature measurement. To maintain product quality, safety, and efficiency during procedures like heating, cooling, and refrigeration, temperature monitoring and control are essential. Thermocouples and thermistors are two of the most popular instruments used to monitor temperature. Although they both have the same function, their design, functionality, and performance traits are different.
What is a thermocouple?
A thermocouple is a temperature sensor made up of two metal wires of different compositions that are joined together at a junction. The voltage is proportional to the temperature difference between the junction and reference temperature is generated when the junction is subjected to temperature gradients. A voltmeter or a temperature controller can be used to measure the millivolt range of voltage that a thermocouple generally produces.
How does a thermocouple work?
The Seebeck effect, which asserts that when two different metals are linked at a junction and subjected to a temperature differential, a voltage is generated that is proportional to the temperature gradient, is the basis of the operation of a thermocouple. It is possible to detect this voltage and connect it with the junction’s temperature.
The metal wires’ composition and the temperature range in which a thermocouple works determine how accurate it is. There are several kinds of thermocouples available with variable temperature ranges and precisions. They are composed of various metal alloys.
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Comparison between thermistor vs thermocouple
Both thermistors and thermocouples provide different features that make them beneficial for different applications Some of the main variations between the two are as follows:
Accuracy
Thermocouples are more precise than thermistors, especially under high-temperature conditions.
Temperature range
Thermocouples have a wider temperature range than thermistors. Thermocoupleshas ability to monitor temperature values between -200°C and 2300°C, then the thermistors measure the temperatures between -100°C and 300°C.
Response time
Compared to thermistors, thermocouples react more quickly. Thermocouples respond to temperature changes instantly, but thermistors might take several seconds.
Linearity
Compared to thermocouples, which provide the nonlinear output thermistor have more linear results. This suggests that more intricate calibration and compensating techniques are required in order to obtain exact temperature measurements using thermocouples.
Cost
In high-temperature applications that need rare metal alloys, thermocouples often cost more than thermistors.
Self-heating
Self-heating can happen when a thermocouple receives current, which can cause temperature readings to be off. Thermocouples are unaffected by this.
Types of thermocouples
The metals used in the manufacturing of thermocouples can be divided into three types.
Base-metal thermocouples
Base-metal thermocouples come with a -200°C to 1000°C temperature range and are created with less costly metals like copper, iron, and nickel They are extensively utilized in sectors including HVAC, food processing, and automobiles.
Noble-metal thermocouples
Noble-metal thermocouples are utilized for high-temperature applications up to 1800°C and are produced from valuable metals like platinum and rhodium. Although expensive, they have high accuracy and stability.
Refractory-metal thermocouples
Refractory-metal thermocouples are used in high-temperature conditions about 2300 centigrade and are generated from rate metals materials like tungsten and molybdenum. They are pricey and demand careful treatment.
Thermocouples Advantages and Disadvantages
Some advantages are listed here
- Wide temperature range
- High accuracy
- Fast response time
- Rugged and durable
- Easy to use and install
Disadvantages are explained here
- Non-linear output
- Limited resolution
- Susceptible to electromagnetic interference
- Requires cold junction compensation
What is a thermistor?
A thermistor is a type of temperature sensor that gauges temperature by using a semiconductor substance. It comprises a tiny ceramic or epoxy bead with a temperature-dependent resistance. A thermistor comes with a negative temperature coefficient NTC or PTC. on the base of its less resistance is low of increases with temperature increases.
How does a thermistor work?
A thermistor’s operation is based on the fact that temperature alters the resistance of a semiconductor material. The resistance of the material is measured and connected to the material’s temperature when a current is supplied through a thermistor.
Types of thermistors
On the basis of their temperature coefficient, thermometers may be roughly divided into two categories:
NTC thermistors
The resistance of NTC thermistors lowers as the temperature rises because of their negative temperature coefficient. Applications including temperature detection, control, and compensation make extensive use of them.
PTC thermistors
PTC thermistors have a positive temperature coefficient, meaning that as the temperature rises, so does their resistance. They are utilized in projects like temperature compensation, self-regulating heaters, and overcurrent protection.
Advantages and disadvantages of thermistors
Different advantages are explained here
- High sensitivity
- Linearity
- Low cost
- Small size
- Good stability
Disadvantages are explained here
- Limited temperature range
- Slow response time
- Non-linear output
- Susceptible to self-heating
