Issue link: https://cp.revolio.com/i/288390
28 | THE DATA CENTER JOURNAL www.datacenterjournal.com • Ring terminals are available for secondary connections (improved reliability) • Electronic contact wear indicator provision (optimized maintenance) • Additional keylock and padlock provisions • Large LCD dot matrix display • Field-replaceable trip unit and/or rating plugs • Protective relaying functions built into the trip unit with up to six programmable contacts • Internal shutter mechanism to iso- late energized line side bus * Some features listed may be considered optional upgrades A circuit breaker upgrade is accom- plished by a process called retrofit where the existing switchgear bus structure is le intact and only the circuit breaker and the draw-out cradle is replaced. is process keeps the existing footprint of the switch- gear such that conduits and cables are not disturbed. Taking on such a project should involve an engineering evaluation of the system. Following are a few key items for consideration: • Trip units – New trip units provide different trip curves, therefore, a coordination study is recommended to appropriately set the new circuit breaker trip points. • 4-wire system - Upgrading to cur- rent technology circuit breakers may require a new neutral sensor and wiring. • Zone Selective Interlocking (ZSI) - If a ZSI system is being utilized, a new ZSI module and interlocking scheme may be required. • Key Interlocking Scheme - e current key interlocking schemes on the existing circuit breakers will have to be incorporated into the new upgrade solution. • Modified Differential Ground Fault System - MDGF system is an ar- rangement of sensors (current trans- formers or CTs) to assure ground fault protection on systems that comprise multiple grounded power sources. As the old technology neutral current sensors are replaced with new sensors, some bussing modifications may be required in the switchgear. CONCLUSION Upgrading existing equipment with state-of-the-art circuit breakers is a cost- effective approach that does not compromise the reliability of the switchgear. Features incorporated in the new circuit breakers include solid state trip unit, communication capabilities, im- proved lubrication materials and, modern composites. e switchgear structure and footprint remain intact, which minimize demolition costs and downtime. Better yet, the electrical power system has been upgraded to support the data center's operations. n References 1 Brocade Communications Systems (www.brocade.com) 2 Cisco Systems, Inc. (www.cisco.com) End-To-End Reliability: Mission Critical Facilities 2014 SPRING CONFERENCE JUNE 1-4, 2014 BOCA RATON RESORT & CLUB BOCA RATON, FL 25 TH ANNIVERSARY 1 9 8 9 – 2 0 1 4 www.7x24exchange.org CONFERENCE KEYNOTE The High Tech Tsunami that is Changing the World John Sculley Former CEO, Apple and Former President, Pepsi Cola MARQUIS PLUS+ PARTNERS GOLD PARTNERS SILVER PARTNERS BRONZE PARTNERS MEDIA PARTNERS PRINCE WILLIAM C O U N T Y , V I R G I N I A 2014 SPRING CONFERENCE CORPORATE LEADERSHIP PROGRAM PARTNERS (AT PRESS TIME) 14S DCJ_8375w525_2fx.q8_DCJ Half page ad 3/20/14 6:12 PM Page 1