Leading the industry in switchgear life extension – Citadel breakers first entered service as fixed mounted elements for doing vacuum conversions on all US legacy medium voltage breakers.
In order to accomplish this task – NBS scoured the used breaker market and obtained the width, depth, and height dimensions on virtually every major U.S.  5 & 15kV breaker.
The tightest of each of those dimensions then became the cuboid envelope for the fixed Citadel element.
To avoid conflicting and overlapping electrical ratings – NBS took the high ground and a more rugged approach. It minimally rated the Citadel as
15 kV – 95 kV BIL – even if it was going to be used on a 5 kV breaker frame conversion. The pole assemblies for the narrow frame would have two (2) ratings only. 1600 amp, 31.5 kA, and 2500 amp, 40 kA.
Therefore every legacy breaker could dimensionally be converted with a narrow frame Citadel element AND meet (or more likely exceed) the original breaker’s nameplate rating.

After a decade of successful prototyping and fabrication of hundreds of Citadel conversions for; GE Magneblast – Westinghouse DH & DH-P –
ITE HV & HK – Allis Chalmers / Siemens MA MC & FC as well as
Federal and McGraw; the engineers at NBS set to work designing building and testing America’s newest most rugged draw-out breaker design.

We invite you to see and learn about the various features and patents on Citadel switchgear.
Virtually or in person – we will bring the Citadel van to your office.

To set appointment just click the Citadel™ Van below.