Thermomagnetic Cut-out Devices

Thermomagnetic Cut-out Devices

Thermomagnetic cut-out devices, also known as thermal-magnetic circuit breakers, are electrical safety devices that protect electrical circuits from overloads and short circuits. These devices combine the functions of a thermal overload relay and a magnetic circuit breaker into a single unit. They consist of a bimetallic strip and an electromagnet that work together to detect and interrupt electrical faults. The bimetallic strip is made up of two different metals with different coefficients of thermal expansion. When the current flowing through the circuit exceeds the rated value, the strip heats up and bends, causing the contacts to open and interrupt the circuit. This thermal protection mechanism is designed to protect against overloads and other long-term heating effects. The electromagnet, on the other hand, provides magnetic protection against short circuits and other high current faults. When a short circuit occurs, the current flowing through the circuit increases rapidly, creating a strong magnetic field that attracts the armature of the electromagnet. This causes the contacts to open and interrupt the circuit, protecting against short circuits and other high current faults. Thermomagnetic cut-out devices are commonly used in residential, commercial, and industrial applications to protect electrical circuits and equipment from damage due to overloads and short circuits. They are available in a wide range of sizes and ratings to accommodate different applications and electrical loads.

electrical safety, thermal overload relay, magnetic circuit breaker, bimetallic strip, electromagnet

— Paul Davis

CITATION : "Paul Davis. 'Thermomagnetic Cut-out Devices.' Design+Encyclopedia. https://design-encyclopedia.com/define/thermomagnetic-cut-out-devices?E=403355 (Accessed on October 14, 2026)"