What type of thermal control device do you need?
There are many different basic types of what is generally classified as
thermal control devices, to make or break an electrical circuit.
In fact, each of these basic types can be expanded into various sub-categories
that are used in so many different applications, they are too numerous
to mention.
The basic types of thermal controls include:
• Cantilever Bimetallic Devices (Resettable & Non-Reset Type)
• Disc-Type Bimetallic Devices (Resettable & Manual Reset Type)
• Adjustable Temperature Type Devices
• Solid State Type Devices
• Electronic Type Control Devices
• Thermal Fuses
Each of these control devices does some things better than others. There are no hard and fast rules and many application factors need to be considered. However, there are some general considerations that determine when certain types of devices are probably your best bet.
Cantilever bimetallic devices, which is the technical term applied to most single element bimetallic type controls, excel at handling electrical loads up to six amps and can operate on currents from milli-volts up to 240 VAC.
Disc-type bimetallic devices are more suitable for applications where you need to interupt resistive current loads of more than six amps.
Adjustable devices are generally used when there is a need to allow for temperature adjustment in the application. These include what are commonly referred to as bulb & capillary type controls, "stack" type thermostats, and adjustable electronic type controls.
Solid state and Electronic type control devices cover a variety of applications. The products used for these applications can range from individual temperature sensors comprised of various materials all the way to entire circuit boards. In some cases, solid state devices can not only generate heat, but regulate it as well. In general, solid state and or electronic type devices are associated with very precise temperature measurement and control.
One-shot, or one time use, thermal fuses are good to use as back-up when a catastrophic occurrence is possible and you would want the product to totally shut-down.
What follows, is a closer look at the manner in which each of these devices operates and the type of applications where they are best used.