What is a key feature of bimetallic strip relays?

Bimetallic strip relays are designed with two different metals that are bonded together. Each metal has a distinct thermal expansion coefficient, meaning they expand and contract at different rates when subjected to temperature changes. As the temperature rises, one metal expands more than the other, causing the strip to bend. This bending action can be used to open or close electrical contacts, effectively functioning as a relay.

This design allows for precise temperature sensing and switching, making bimetallic strip relays useful in various applications, such as thermostats and overload protection in motors. The principle relies on the physical properties of the two metals working in tandem, underscoring the importance of their differing expansion characteristics in the relay's operation.