What safety device is used to protect electrical circuits from overcurrent?

A fuse is a critical safety device designed to protect electrical circuits from overcurrent conditions that can cause overheating and damage. When the current flowing through the circuit exceeds the fuse's rated capacity, the fuse element melts or breaks the circuit, effectively interrupting the flow of electricity. This action prevents potential hazards such as electrical fires or equipment damage, ensuring the safety and reliability of the electrical system.

Fuses are typically rated for specific current levels and have a predictable response time, making them effective in protecting circuits in various applications. They are simple to use and can typically be replaced easily after being tripped. Other devices mentioned, such as relays, capacitors, and transistors, serve different functions in electrical circuits, but they do not provide direct protection against overcurrent in the same way a fuse does.