Thermal Switches (Hi REL)

Thermal switches are known for being one of the most reliable and efficient ways to control temperature and provide warnings for when temperatures reach a high or low limit . A thermal switch can cut power to a device, or engage a fan or a heater, for example, when the surrounding temperature becomes critical.

A thermal switch can be described as an electro-mechanical device which opens and closes electrical contacts to control an electric circuit with set limits in relationship to temperature.

Depending on the limits of the switch, the contacts will close/open when the temperature reaches a certain level, which will either make or break the circuit and turn a device on or off.  Single-pole double-throw variations are also available.

Thermal switches are used throughout many different industries, for example; industrial applications, military, aircraft and aerospace, medical equipment, hydraulic devices, turbines and many more. They have three main purposes;

Indication of overheating – they can provide a warning when temperatures reach or come close to reaching the set limit.

System Temperature Control – used to maintain a temperature and keep it within a set limit.  High temp limit, as well as low-temp (anti-freeze) control are typical applications.

Safety Shutoff – as a final safety feature to cut the power to a device based on the temperature reading

Application parameters such as temperature set point, tolerance, response time and desired mounting and probe configuration will determine the type of switch required for the application.

We offer three different types of thermal switch from CPI these are;

• Snap Stat Thermal Switches
• Plug Stat Thermal Switches
• Rod and Tube Thermal Switches

Each one is suited to a different application area and has specific sensitivity levels and temperature profiles.

SnapStats have a temperature range 0°F – 300°F. The Contact movement in the temperature switch is achieved by using a bimetallic snap disc. The Snap action provides shock and vibration immunity and a broader differential. Set point range: 0°F-300°F (-17.8°C-148°C).

Different configuration options include;

• Surface Mount
• Flange Mount with Probe
• Thread Mount
• Hermetically Sealed
• Clamp Mount
• High Dielectric strength

PlugStats have a temperature range of 0°F – 650°F. The contact movement is achieved using the different expansion rates of two metals fused together. This is a slow-make-and-break device, which provides very close tolerance temperature sensing, with a small differential. Set point range: 0°F-650F (-17.8°C-343°C)
Configuration options include;

• M1 Series – Solder Terminals
• M2 Series – Glass-sealed Connectors
• L Series – Ground-to-Case
• S Series – Dual-Setpoint

Rod & Tubes have a temperature range of 0°F – 1750°F). The contact movement in the switches is achieved via differences in coefficients of expansion of two materials, in this case the outer tube and the internal rod. This product offers very rapid response time and very high temperature sensing. Set point range: 0°F-1750°F (-18.3°C-954°C).
Configuration options include: 

• X1 Series – 0F – 850F
• X2 Series – 850F – 1750F
• AB Series – SPDT
• W Series – Ground-to-Case

Thermal switches are often selected for use because;

• They are small devices and light in weight making the suitable for applications where space is tight.
• They are good value for money and often less costly than other switching alternatives.
• They are simple and easy to install – no separate power required
• They are easy to maintain and to check the functionality – some designs even have a self test capability.
• It is easy for specifications to be established for use in various systems.

View our range of thermal switches above – for more information please contact us.