What are Circuit Breakers and How are They Used?

While electric power has greatly revolutionized our daily lives with the introduction of countless advanced technologies, electricity remains a volatile force that can be very destructive if uncontrolled. Overload conditions are an occurrence within circuitry where an excess amount of current is drawn from the supply. Well surpassing the needs of system electronics, overload current can easily cause damage to sensitive components and appliances. Circuit breakers are a type of circuit protection device that are commonly found within buildings and homes, preventing excess current from damaging components with their ability to interrupt current.

Circuit breakers are a type of mechanical switching device, capable of breaking contacts manually or automatically. When breaking under normal conditions, a circuit breaker can be managed either manually or with a remote control. During abnormal conditions, such as when there is an overload condition, the circuit breaker will often break automatically. Standard circuit breakers feature fixed and moving contacts known as electrodes, those of which normally sit closed to permit the flow of electricity throughout an electronic circuit. If a fault is detected and the system’s trip coil is activated, a mechanism will separate the contacts apart so that the circuit is opened and current will be prevented from reaching the rest of the system.

As contacts pull apart from one another, an incident known as an Arc Phenomenon will occur. During this phenomenon, an arc will be struck between the separating contacts, continuing the flow of electricity. A great amount of heat will also occur from the striking of the arc, thus it is crucial that the circuit breaker is able to quickly extinguish it. Arcs are generated due to the separation of contacts as the contact area of the device will suddenly drop while current density rises. As temperatures spike, the air or oil medium will be ionized and become a conductor for the arc.

The method of extinguishing the arc will often differ based on the type of circuit breaker and its construction, though all tend to fall under high and low resistance methods. With high resistance methods, the resistance of the arc is increased to a point in which the current will not be able to sufficiently transfer power. This can be achieved in a few ways, including increasing the length of the arc, cooling the arc, minimizing the arc’s cross section, and splitting the arc. High resistance methods are quite common to DC circuit breakers and low capacity AC circuit breakers as the arcs produced by such equipment will often have extreme heat.

With the low resistance method, arc resistance is kept low so that the arc can naturally extinguish as current ceases. Low resistance methods rely on the deionization of the arc’s medium, ensuring that the possibility of a restrike is prevented. This can be carried out in a few ways, often being achieved through pressure increases, contact gap widening, arc cooling, or the gas blast effect. The low resistance method is often used by high power AC circuit breakers for the minimization of arc restriking.

When searching for a circuit breaker for a particular assembly or system, such components may be classified based on their voltage applications, installation location, design characteristics, and arc extinguishing method. Air magnetic circuit breakers, air blast circuit breakers, oil circuit breakers, sulfur hexafluoride circuit breakers, and vacuum circuit breakers are all popular variations, each featuring different operational characteristics, advantages, and disadvantages that can make them beneficial for certain applications. Once you have established which circuit breakers or circuit breaker parts that you need for your operations, let the experts at Fulfillment by ASAP help you secure everything you need with ease.

Fulfillment by ASAP is a premier supplier of aviation, NSN, and electronic parts, providing customers access to an inventory containing over 2 billion items sourced from leading global manufacturers. With AS9120B, ISO 9001:2015, and FAA AC 00-56B certification and accreditation, we ensure that all parts have been thoroughly tested, inspected, and cross-referenced for their quality. If there are specific items that you would like to procure from us, we invite you to first start with a quote for your comparisons which you may receive through the submission of an RFQ form on our website. Get started today and see how Fulfillment by ASAP is revolutionizing the procurement process for our customers.


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