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What Is A Circuit Breaker?
Circuit breakers are electrical devices whose purpose is to protect all parts of the circuit in which they are engaged from electrical conditions deemed inappropriate or unsafe. Different circuit breakers offer different attributes and features, but the most basic circuit breaker monitors current for overload and short circuit. Each of these conditions is hazardous to the circuit, the electrical system, the load, the supply and operators of the equipment. When exposed to an overload or a short circuit (or any of dozens of other specific programmed conditions), the device is designed to open automatically to interrupt the circuit quickly and completely. Fault interruption is very dangerous and produces arcs that can contribute to explosive events in air break devices.
Circuit breakers operating at optimum efficiency and accuracy can play a huge part in reducing potential arc flash hazard. In low-voltage applications, most circuit breakers have all or most of their protective behaviors integrated into the device, while in higher voltage breakers, it is common to mount the protective relaying separate from the actual breaker element. However, even that is changing now in the most modern applications.
A circuit breaker is either integrally designed or programmed to trip or open automatically at designated points on an inverse time-current curve. The higher the overload, the sooner the breaker will open. A breaker may allow 125% of rated current to flow for five or more minutes, whereas a breaker exposed to 600% or more (fault condition) of rated current should trip instantly. In addition to basic short circuit and overload protection, most 600V class breakers of the last several generations allow someone to customize the curve on which the breaker trips.
Breakers may monitor and protect for ground fault conditions, under or over voltage conditions, under or over frequency conditions and phase failure or phase sequence. They even may be paying attention to the condition of other circuits in the same system (a feature sometimes known as zone interlock).
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Main Components of a Circuit Breaker
Common Types of Circuit Breakers
Medium-voltage air breakers. From the early 1900s until the earliest 1980s, 5 and 15 KV breakers were either oil or air break type and in the second half of that period it was all air. The very largest industrial installations built before 1980 will still be running large distribution through air circuit breakers. Yet their major manufacturers are very little help when parts or replacement breakers are needed to keep a plant running. That is where we come in. We can also often provide vacuum retrofitted breakers to replace your failed air breakers as easily as rolling it into the existing cabinet.
Air circuit breakers. A step heavier than insulated case breakers, air breakers are completely modular with more of the internal parts and subassemblies externally accessible. These are designed for very long service life. Many generations of these products were made backwards compatible or conversely upgradeable to new products without replacing their switchgear. More recent generations of all manufacturers’ products are not backwards compatible, making our inventories of used and unused surplus product very important for keeping you up and running or allowing you to expand your existing gear. If you have a 15-year-old piece of switchgear, it is still in its youth as far as its design life, but its manufacturer stopped supporting it long ago. That is where we step in, and this product is one of the best examples of how we can help you keep the lights on and the conveyors moving.
Medium-voltage vacuum breakers. Like air circuit breakers, these breakers have been available since the early 1980s and will remain the standard for years to come, as this is a vastly superior technology. Our inventories are growing and are available to get you back online now.
Insulated-case circuit breakers. These larger size breakers can be customized with programmers and accessories and are field serviceable. These devices are found in heavier applications — usually industrial facilities where the product is expected to withstand more demanding service. Our inventory and service technicians are well up to the task, and this product has us out in the field for service and repair more often than any of our other product lines.
Molded case circuit breakers are in your home panelboard, schools and commercial buildings, gas stations and strip malls. This is the most common type of low-voltage circuit protective device, and we have the country’s largest and most comprehensive inventory. ROMAC has the most structured and rigid work scope for reconditioning them, with 24/7 service to get it for you when you need it.
ROMAC's Reconditioned Circuit Breakers
Reconditioning is the process of returning electrical equipment to a safe and reliable operating condition based upon the design of the original manufacturer at the time of manufacturing. ROMAC carries inventory from all major OEMs, including: GE, Cutler-Hammer, Siemens, SquareD, as well as vintage breakers from manufactures, such as Hieneman, Frank Adams, Trumbull, Zinsco, Challenger, and American FPE. ROMAC follows PEARL industry standards to recondition a circuit breaker switch, including procedures to test, inspect, disassemble and recondition – including disassembly, cleaning, drying, deoxidizing, removal of corrosion, degreasing, plating, painting, lubricating and adjusting of the circuit breaker. After reconditioning, subassemblies can be reinstalled in the now cleaned and painted enclosure or frame, including the addition of upgrades or options to improve the apparatus’s performance. Assembly of the reconditioned components and subassemblies is followed by final inspection and testing. As with all testing, inspection and reconditioning operations, final inspection and test results are recorded onto the valuation and test forms included with the standard.