Switchgear is a series of electrical disconnects, fuses, and circuit breakers that isolate electrical equipment. Switchgear elements can be used in combination or independently. In either case, their functions are the same: to de-energize equipment prior to maintenance, protect equipment against fault currents, and improve system availability by allowing access to generator power. Electric systems, and those who maintain them, rely on the safety provisions of switchgear. However, the safety of switchgear itself is a critical concern.
Improving the safety of switchgear power systems
Although different buildings have different power system needs, the following strategies can help all buildings enhance the safety of switchgear power systems.
Arc resistant breaker technology
Here, the term arc resistant refers to a breaker’s ability to extinguish electrical arcs. Older circuit breakers contain an air extinguishing mechanism, which extinguishes an arc with a puff of air; or an oil extinguishing mechanism, which extinguishes an arc with a jet of oil. Sulfur hexafluoride gas breakers and vacuum breakers are newer, more arc resistant breakers. Gas breakers stretch an arc using a magnetic field, and then extinguish it with sulfur hexafluoride gas. Vacuum breakers extinguish an arc by stretching it only a small amount, usually
Pressure release vents
Switchgear housing that contains pressure release vents mitigates arc flash events by dispersing their pressure through the vents, which are usually located on the rear of the housing near the top. This protects workers against equipment focused arc flashes (a.k.a. arc-in-a-box) that have ejection potential. Housing with pressure release vents can be retrofitted around existing equipment.
Metal clad housing
Metal clad housing can contain explosive, equipment focused arc flashes, protecting workers and retarding the spread of fire to surrounding equipment. As with housing that contains pressure release vents, metal clad housing can be retrofitted around existing equipment.
Remote operation
Some switchgear power systems have remote operation and monitoring features that allow workers to perform equipment readings and operate certain mechanical features remotely. Three common features of remote operation systems are: the ability to perform data readings from the convenience of an office computer, the ability to work on energized equipment with the use of a remote racking device, and the ability to open and close a breaker with a remote control device.
Thorough maintenance and testing
Switchgear should be thoroughly maintained and tested in preparation for fault currents and power outages. Medium voltage gear that is in good condition should receive gear specific maintenance and electrical testing at least annually. Emergency power supply system (EPSS) switchgear should be maintained and tested according to NFPA 110.
Prime Power specializes in switchgear
At Prime Power, we know the importance of switchgear to building safety, worker safety, and emergency power availability. That is why we offer a full range of services aimed at maintaining, testing, and improving switchgear power systems, including: scheduled maintenance, annual testing, infrared scanning, repairs, modernization and retrofits, and new installations. If your gear needs maintenance, testing, retrofitting, or replacement, call Prime Power today for a free consultation.
