Circuit Breakers and Their Types

A circuit breaker is an electro-mechanical device used to protect electrical circuits from overloads. They are used to protect the wiring in circuits from the risk of fire due to currents exceeding the rated capacity of the circuit. Circuit breakers employ switches that open automatically when excess currents are detected and require manual resetting. Circuit breakers are generally rated based on the amount of current that can be safely carried by the circuit being protected by the breaker. In this blog, we will take a look at the most common types of circuit breakers and their unique characteristics.

Standard Circuit Breakers

Standard circuit breakers are devices used in the electrical panels of homes or businesses that operate on 120V/140V single-phase electrical power. Standard circuit breakers are usually available as single or double pole breakers, the latter being used for higher voltage loads such as circuits that supply power to an electric dryer or range.

Magnetic Circuit Breakers

Magnetic circuit breakers are circuit breakers that use a solenoid or electromagnet within the device to generate a magnetic field whose strength varies linearly with the magnitude of the current in the circuit. When the current exceeds the rated value of the breaker, the magnetic field strength in the solenoid causes the breaker to trip open, thereby interrupting the flow of current.

Thermal Circuit Breakers

Circuit breakers of this type make use of a bimetallic strip in the breaker through which the circuit current flows. As the current increases in the circuit, heat is generated until the bimetallic strip reaches a point of deformation, causing the breaker to trip, open the state, and interrupt the flow of current in that circuit. When the current drops to zero, the bimetallic strip cools and the breaker can be reset. Thermal circuit breakers are temperature sensitive. In colder operating conditions, the trip point is higher than when in warmer conditions.

Thermal Magnetic Circuit Breakers

Thermal magnetic circuit breakers use both sensing and tripping mechanisms to provide circuit protection for a device. The sensing mechanism is based on heat, while the tripping mechanism is based on magnetics. In general, magnetic protection responds to high magnitude current conditions like those resulting from a short circuit, while thermal protection allows for overcurrent conditions to occur in limited durations.

Hydraulic Magnetic Circuit Breakers

These circuit breakers provide a more precise method of tailoring the circuit protection to a desired application. Circuit breakers of this type use a solenoid wrapped around a tube which contains an iron core, spring, and dampening fluid. In the event of an overload condition that is not the result of a short circuit, the magnetic field strength begins to exert a force on the iron core, with the hydraulic fluid inside dampening the speed of travel. Therefore, the presence of the dampening fluid and the viscosity it provides introduce a time delay between the onset of the overcurrent condition and the trip condition of the breaker. If the condition persists, the core’s movement causes the magnetic reluctance of the circuit to drop and allows the breaker to trip. One of the main advantages of hydraulic magnetic circuit breakers is that they are not affected by temperature conditions.

While these are the most common types of circuit breakers, there are many others. For all types of circuit breakers and much more, look no further than Paragon Purchasing. Owned and operated by ASAP Semiconductor, we can help you find all types of parts for the aerospace, civil aviation, defense, electronics, industrial, and IT hardware markets. Our account managers are always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at +1-714-705-4780. Let us show you why we consider ourselves the future of purchasing.


November 20, 2023

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