What is a Thermistor, How it Works, and What Does it Do?

Last updated on September 14th, 2023 at 06:03 am

A thermistor can be defined as a semiconductor that contains lower resistance material than conducting material and a resistor that reacts to temperature. The word “thermistor” comes from two words: “ thermal “  and “ resistor ”.

Hence, it refers to thermally sensitive resistors that are truly accurate and effective sensors for measuring temperature.

It’s a type of electrical element that shows a change in electrical resistance with changes in temperature.

Thermistors are designed in a way that they are largely sensitive to temperature variations and are generally used in various electronic biases and systems for temperature control purposes.

The resistance of a thermistor depends on the material from which it’s made. Their construction material consists of metallic oxides, binders and stabilizers that are pressed into wafers and cut into chips, with the rate of emulsion paraphernalia determining their resistance or temperature wind. Therefore, they serve as an affordable, accurate, and dynamic system for measuring temperature.

Thermistors are used to monitor the temperature around a device. Temperatures detected by thermistors impact equipment and are used for temperature seeing and overload cutouts.

Thermistors can be set up in various circuits, outfits, and biases, furnishing a low-cost system for temperature monitoring.

There are several configurations of thermistors, the most common ones being hermetically sealed and flexible( HSTH series), bolt-on and washer types, and tone tenacious face-mounted style.

HSTH thermistors are completely sealed with a plastic polymer jacket to cover the seeing rudiments from moisture and corrosion.

How does a Thermistor work?

The introductory working principle of a thermistor is that its resistance depends on temperature. The ohm meter, which is a device that measures electrical resistance, measures the resistance of a thermistor.

When examining thermistors, it should be flashed back that they do not read values, but their resistance varies with temperature. The substance applied to a device determines the amount of resistance. 

All resistors change in relationship to temperature, an effect that is measured by temperature measure resistance, which is represented by a change in resistance.

With typical resistors, the temperature changes during performance. For thermistors, a large temperature measure resistance change is necessary to be suitable to measure temperature.

A thermistor is placed in the body of a device for which it has to measure the temperature and is connected to an electrical circuit.

When the temperature in the device rotates, the resistance in the thermistor changes, which is recorded by the directly connected circuit and adjusted according to the set temperature.

Thermistors have two lines, with one line connected to the excitation source that measures the voltage of the thermistor. The thermistors offer a more sensitive and accurate reading as they have the capability to give a huge change in resistance value when there is a temperature change.

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Types of Thermistors

Primarily, there are two types of thermistors predicated on their resistance-temperature characteristics: Negative Temperature Measure( NTC) thermistors and Positive Temperature Measure( PTC) thermistors.

These two types have observably different conduct in response to temperature changes, which makes them suitable for various operations. Among NTC and PTC thermistors, NTC thermistors are the more preferred.

Negative Temperature Measure( NTC) Thermistors

NTC thermistors parade a drop in electrical resistance as the temperature increases. It shows that their resistance drops snappily with rising temperatures. They are the more common type of thermistors and are used in a wide range of operations.

Operations of NTC thermistors include:

  • Measurement of temperature and control in electronic bias and appliances.
  • Thermal protection in circuits to help overheating.
  • Temperature compensation in electronic factors and sensors.
  • Climate control systems and HVAC systems.
  • Temperature seeing in automotive systems, analogous to machine temperature monitoring. 

Positive Temperature Measure( PTC) Thermistors

PTC thermistors parade an increase in electrical resistance as the temperature increases. Unlike NTC thermistors, the resistance of PTC thermistors sharply increases at a particular temperature threshold. This unique behavior makes them suitable for specific operations.

Some operations of PTC thermistors are:

  • Overcurrent protection in circuits and bias.
  • Self-regulating heaters.
  • Motor starting bias.

Where is a Thermistor Used in Industrial Heating?

Thermistors are used in various artificial heating operations to cover and control temperature. Their perceptivity to temperature change makes them precious tools for icing precise and reliable temperature operations in artificial processes.

Here are some common artificial heating operations where thermistors are used

  • Process Control and Monitoring: Thermistors are constantly integrated into heating systems to measure and regulate the temperature of a process.
  • Ovens and Furnaces: Industrial ovens and furnaces use thermistors to cover and control the temperature inside the heating chamber.
  • Heat Exchangers: Thermistors can be placed in heat exchangers to measure the temperature of liquids or feasts as they are heated or cooled. This information is used to optimize heat transfer effectiveness and maintain temperature consistency.
  • HVAC( Heating, Ventilation, and Air Conditioning) Systems: Industrial HVAC systems calculate on thermistors to control the temperature of air or fluid in large marketable and artificial structures. Thermistors help maintain comfortable working conditions and energy effectiveness.
  • Plastic Welding: In industries where plastic welding is performed, thermistors can be used to control the temperature of heating rudiments, icing a strong and harmonious bond between plastic corridors.
  • Semiconductor Manufacturing: Precision temperature control is critical in semiconductor fabrication. Thermistors are used to cover and regulate the temperature of various processes, including etching, deposit, and diffusion.
  • Environmental Chambers: Environmental test chambers used for testing products under extreme temperatures constantly use thermistors to achieve precise temperature control.
  • Hot Water Heaters: In artificial settings where hot water is demanded for various processes, thermistors can be used to cover and regulate the temperature of the water to meet specific conditions.
  • Thermal Monitoring and Safety: Thermistors are also used for safety purposes. They can be incorporated into heating equipment to describe overheating and sensor safety shutdowns or admonitions to help damage or accidents.

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A thermistor is a docked version of the term thermal resistor and is a passive component whose resistance changes as the temperature in a system changes.

The thermistor detects changes in temperature that influence equipment and is used for temperature sensing and overload cutouts.

In most cases, thermistors are at the heart of any temperature-measuring device due to their cost and exactness. The resistance of a thermistor to electrical current changes as the temperature changes.

The two general classifications of thermistors are negative temperature coefficient( NTC) and positive temperature coefficient( PTC), with the NTC interpretation being the most common type.

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