What is the Function of the Application of the Temperature Switch

Switches are essential to control system components in every electrical and electronic application. In the industrial sector, different switches are used for various purposes, such as toggle, slide, push button, rotary, liquid level, temperature, pressure, and many more. With their reliable performance and simple design, temperature switches can be relied upon to provide accurate and safe temperature control.

Temperature Switch

What is Temperature Switch?

A temperature switch is an expert mechanical tool used to display and manipulate the temperature of numerous production and commercial processes. This cost-effective solution can measure temperature in even the most confined spaces by switching the ON and OFF transfer contacts as soon as a predetermined temperature is reached. The temperature switch symbol is depicted below. This device offers a reliable and efficient temperature control option for professional applications.

Temperature Switch(1)

The input temperature, in particular, determines the switching situation of those switches. As such, this function is used as a safeguard against overheating. In addition, these switches are responsible for accurately monitoring the temperature of equipment and machinery, thus providing critical protection against potential overheating.

Temperature Switch Construction

These components are designed to provide a reliable and professional switch solution. Each component is carefully selected to ensure optimal performance and dependability.

The temperature-sensing bulb utilizes a fluid that responds to variations in temperature. As the spindle moves towards the switch, it causes an ON and OFF action based on the set point of the switch. This process is reliable and efficient, making it a professional-grade temperature-sensing solution.

Temperature Switch(2)

Working Principle

A temperature switch’s operating relies upon the temperature versions inside an enclosed space. Therefore, the temperature switch is designed to detect temperature changes and activate the switching mechanism. Once the sensing probe detects a boom in temperature, the electrical contacts are opened. This allows for precise control over temperature variations, ensuring the reliable operation of the system.

By utilizing this technology, engineers can ensure that the system is functioning optimally, thus providing a safe and efficient working environment. With its professional and reliable performance, the temperature switch can be a valuable asset for any home or workplace.

Types of Temperature Switches

These switches are categorized into two types: mechanical and electronic.

Mechanical Temperature Switch

Mechanical temperature switches are an essential tool for measuring or detecting temperature change. Available in bimetallic and liquid expansion, they are reliable and accurate, making them the perfect choice for any professional project.

Temperature switch

Bimetallic Temperature Switch

The bimetallic temperature switch or bimetallic thermometer relies on the bimetallic strip to convert temperature into mechanical displacement. This strip is based on the principle of metal expansion when heated. As the temperature changes, the volume of the metal is altered accordingly.

Metal’s physical dimension is highly dependent on its temperature coefficient, meaning that metals of similar temperatures may have different changes in their physical dimension. This highlights the primary relationship between the difference in a metal’s physical dimension and the temperature that causes it.

The advantages of a bimetallic temperature switch are often compact size and cost efficiency. However, these come with certain drawbacks. Namely, accuracy is often lower than other temperature switch types, it is prone to vibrations and shocks, it cannot handle high temperatures well, and its performance will degrade when the ambient temperature changes.

Liquid Expansion Thermometer

Its susceptible fluid-filled bulb system allows an expansive amount of liquid to be held with maximum accuracy. As the bulb is heated, the enclosed liquid will expand and increase the fluid pressure within the bulb, triggering the connected pressure switch to activate.

The advantages of a liquid expansion thermometer are undeniable: lower costs, compact size, and more accurate temperature readings. However, there are some disadvantages, such as a high response time, the possibility of leakage, and resistance to temperature and shock.

Electronic Temperature Switch

This professional-grade temperature switch is designed to measure temperature through a power supply source, measuring element, and electronic circuit. The switch utilizes a switching signal that changes in proportion to the temperature, allowing for precise calculations. Electronic temperature switches are ideal for applications where high accuracy is essential.

Electronic Temperature Switch

Temperature Switch Circuit Diagram

This circuit is designed to provide automatic temperature control for cooling fan systems. It functions by automatically regulating the temperature of temperature-regulating equipment. This ensures reliable, efficient, and safe operation, allowing optimal cooling performance.

Temperature Switch(3)

This circuit provides automatic temperature regulation for cooling fan motor control. As illustrated in the diagram above, the circuit is connected in a 2-wire temperature switch configuration, which is responsible for the activation of the motor. When the temperature rises to the point where the switch is activated, it will close two ‘F’ contacts, which will then, in turn, activate the motor. This provides a reliable, professional solution for controlling temperature-sensitive equipment automatically.


  • Temperature switches are specifically engineered to be integrated into various heating systems, boilers, circulation pumps, air heaters, and burners. These switches provide precision control and temperature monitoring to ensure reliable operation and consistent performance in any environment.
  • They are mainly used in pharmaceuticals, automotive engineering, foodstuffs, etc.·
  • These switches may be used with pumps, boilers, and heating systems.·
  • Thermal switches are utilized explicitly in kitchens and eating places to test the temperature of the cooked meal.
  • These switches play a crucial role in processing information & protecting equipment.
  • These switches are used in various applications like RF power amplifiers, motor drives, power supplies, etc.

Purpose of a Temperature Switch

The temperature switch is specifically designed to monitor the temperature of machinery and equipment in industrial settings. Its primary purpose is to protect machinery from overheating and limit temperature fluctuations, thereby ensuring the longevity and reliability of the equipment. With an accurate and reliable temperature monitoring system, industries can remain confident that their machinery and equipment are operating safely and efficiently.

What is the Deadband of the Temperature Switch?

The deadband of the temperature switch is the temperature difference between the increased and decreased set points. Professionally speaking, this is an essential factor that should be taken into account when setting up temperature control systems. Adjusting the deadband accordingly ensures optimal temperature regulation and efficiency.

Are Temperature Switches Normally Open or Closed?

When the temperature switch is Normally Open (NO), the switch is designed to stay open at a minimal temperature. Similarly, the switch is designed to stay closed when it is Normally Closed (NC).

A temperature change activates this switch, and its condition will change from NO to Normally Close or NC to Normally Open. The NO thermal switch contacts usually stay open until a temperature increase is detected, at which point they will close.


In conclusion, temperature switches are a valuable and reliable tool in the industrial sector due to their ability to provide accurate and safe temperature control. With their easy to use design and reliable performance, temperature switches are the most widely used for monitoring and controlling the temperature of various industrial machinery. In summary, switches play a vital role in controlling system components in every electrical and electronic application and temperature switches are no exception.

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