More about Circuit Breakers

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Circuit breakers are devices used in electrical circuits that automatically open when the current exceeds the specified level. They help protect sensitive components in these circuits from damage caused by current overload and related system faults. Perhaps the most familiar circuit breakers are the switchgear cabinets (breaker boxes) found in many homes, although there are a great variety of circuit breaker types. Extremely large devices are used for power grid applications, while many pieces of electrical equipment have small breakers built into their design.



Circuit breakers operate through various methods, and may respond directly to thermal and/or magnetic changes, or be triggered by other sensing devices and controls. Microprocessors, for example, are frequently used to control power distribution in large-scale industrial facilities. Other circuit breakers use electromagnets that grow stronger as the current rises; with a high enough current, these electromagnets, known as solenoids, eventually force open the switch. In high-voltage systems (over 72,500 V), additional materials, such as oil and sulfur hexafluoride, are often used to help extinguish the electric arc. Typically, these high-voltage breakers involve a solenoid and cool the arc with a blast of gas.



In addition to the circuit breakers used for high-voltage operations, there are a wide range of breakers used for household and commercial applications. These circuit breakers include vacuum circuit breakers, air circuit breakers and mini circuit breakers. Circuit breakers are available for both AC and DC systems, and many distributors also stock and sell obsolete units for older machines and equipment.



Virtually every industry, from marine and medical to telecom and power generation, utilizes some type of circuit breaker. Most buildings also use circuit breakers, even though power grids deliver a standard voltage to each. These domestic circuit breakers, often in the form of a switchbox, ensure that appliances do not draw too much power through building wires, which can cause them to melt.