Educate Yourself About Arc Resistant Switchgear Retrofits: What Exactly Are Their Benefits?

Switchgear (e.g. fuses, circuit breakers, and electrical disconnects) is the component in an electric system which isolates electrical hardware, keeping it from being damaged by a power current that may be too high, which often can happen during a power surge. To stop such damage-and also to protect against fires and injuries-facilities commonly use one of the following kinds of circuit breakers (CBs): oil, gas, air, or vacuum.



Going Over Oil Circuit Breakers

An older kind of switchgear, oil circuit breakers count on oil vaporization to deliver a burst of oil through arcs which extinguishes them. Oil CBs tend to be the target of retrofits that replace them with more modern technologies.



Reviewing Gas Circuit Breakers

Gas circuit breakers commonly stretch arcs with a magnetic field, and then count on the dielectric strength of SF6 gas to put them out.



Examining Air Circuit Breakers

As their name suggests, air circuit breakers apply air as an extinguishing method. This is accomplished by (a) puffing air at an arc, or (b) swinging the contacts right into a sealed chamber, where the arc is put out by air that escapes from the chamber.



Examining Vacuum Circuit Breakers

Vacuum circuit breakers put out arcs just by stretching them. Since there is absolutely nothing to ionize besides the contact material, vacuum CBs need only stretch arcs a little amount, generally as few as 3mm. Thanks to their extinguishment effectiveness, vacuum CBs are often reported to be "arc-resistant."



Some Great Benefits of Arc-Resistant Switchgear Retrofits

Arc-resistant switchgear is useful for any facility that desires to reduce the impact of internal switchgear faults, for example: ruined equipment, building fires, as well as injured equipment workers. In many instances, these tragedies occur simultaneously, presenting a significant financial burden which the right retrofits may have prevented. To recognize the advantages of arc-resistant retrofits, it will help to consider exactly what can transpire in their absence.



The Anatomy of an Internal Switchgear Fault

An internal switchgear fault that comes from an un-extinguished arc typically occurs in four distinctive stages, with stages 2 and 3 lasting only milliseconds:



Reviewing Phase 1

Also referred to as the compression phase, this is where arcs build until they achieve the highest level of internal pressure.



Reviewing Phase 2

Also known as the development phase, this is when the pressure relief vent actually starts to open up as arcs display wave action and possible under-pressure.



Phase 3

Also known as the emission phase, this is the time the pressure relief vent has opened and the gas in the gear housing achieves arc temperature.



Reviewing Phase 4

Also called the thermal phase, this is when arcs consume all combustible substance in their environment until they're extinguished.



Since phases 2 and 3 occur in a matter of milliseconds, it's not possible for equipment workers to flee the danger zone before stage four starts. Consequently, 2 ideal protective measures to protect against internal switchgear arcs are (a) strategic retrofits to outdated circuit breaker systems and (b) exchanging vulnerable gear housing with more powerful housing to minimize exterior effects (e.g. exchanging metal-enclosed housing with metal-clad housing). Before it makes a decision on retrofits, a business should have its switchgear checked out by a power generator services provider that specializes in switchgear retrofits.



While preparing to write this article, I learned a lot about transfer switch maintenance and switchgear maintenance at PrimePower.com