Low voltage switchgear retrofill

Eaton’s retrofill option replaces both the breaker or starter element and the envelope in which it engages mechanically and electrically. An ideal alternative for customers desiring the interchangeability of vintage power circuit breakers with those of new Eaton switchgear, retrofill conversions provide:

• All necessary drawings, literature, testing and documentation
• Circuit breakers with the latest technology and increased capabilities that can be integrated into existing enclosures
• Conversions of fixed mounted circuit breakers to drawout construction for improved uptime and reliability
• Readily available mechanism parts and control components from current  production
• Drastically reduced downtime and installation costs compared to new switchgear
• LV power circuit breakers directly interchangeable with new Eaton switchgear circuit breakers of same rating
• LV circuit breaker-to-motor starter retrofills that utilize same components supplied in new Eaton motor control applications
  

Generator circuit breaker conversion 

Eaton makes it possible to extend the useful life of generator circuit breaker systems using reconditioning and conversions that:

• Designed and certified to ANSI/IEEE standards
• Incorporate newer interrupting technologies and improvements that enhance reliability and safety while reducing downtime and maintenance costs
• Include medium voltage circuit breaker components
• Available with Eaton power generation engineering and support services
  

Background: Gaston Hydro Station, located in Thelma, N.C., along the banks of the Roanoke River, is integral with the Gaston Dam that backs up water from the river into the Lake Gaston reservoir. When water is routed through the powerhouse turbines, the station’s four generators can produce up to 55 megawatts each, for a total capacity of 220 megawatts. The power house, whose operation dates back to 1963, is used for continuous, peaking or black start power for other generating plants on the Dominion Energy Grid. 

Problem: The original four circuit breakers installed at the Gaston Hydro Station in 1963 used oil as an interrupting medium and were not designed to the new generator circuit breaker standard. The circuit breakers also required de-tanking to access the contacts. This was expensive and required an outage of up to a week for one substation team. Spare parts were becoming difficult to obtain and their cost was increasing. Additionally, oil spills that could occur during maintenance outages would cause environmental issues.

Solution: The four original circuit breakers were replaced with conversions that used fixed-mounted vacuum circuit breaker elements rated and manufactured to distribution circuit breaker standards. The circuit breakers were mounted in a ferrous- steel enclosure with a stainless-steel top that prevented circulating currents from melting the steel between the bushing mountings. Since C37- 59-1992 had not been published at the time the conversion circuit breakers were manufactured, there was no IEEE Standard to cover their design and test. A total of five conversion circuit breakers were furnished so the utility would have one spare unit. The circuit breakers performed satisfactorily, but some of the maintenance issues remained and a few new issues surfaced.

Many years later, Dominion Energy decided to replace the first vacuum breaker conversions with new replacement vacuum circuit breakers. The utility’s wish list for the project included the ability to reduce maintenance costs; improve overall system reliability and uptime; reduce maintenance outage time; increase short-circuit capability back to 63 kA; meet C37.59-2007 standards; gain drawout construction with a spare circuit breaker element; eliminate painting, rusting, bus torqueing and cleaning, filters and moisture issues; and maintain bushing termination locations, among other issues. The only way to meet all of the utility’s requirements was to manufacture a unique circuit breaker enclosure that included a number of new design approaches.

Results: During the first three years after installation, there were numerous rain and snowstorms, several hurricanes and one earthquake but no generator circuit breaker outages have been reported and no unscheduled maintenance has been required. The solution’s design enables extremely short outages for scheduled maintenance, as opposed to requiring several days like the previous equipment. Based on the circuit breakers’ capabilities and the rugged design of the switchgear system, a service life of 25-35 years is expected.