AZZ I Central Electric 7900 U.S. Highway 54Fulton, Missouri 65251

Phone: (573)642-6811

www.azz.com

CEM-104-0113

UTILITY GRADE ARC-RESISTANT SWITCHGEAR

CENTRAL ELECTRICTM

ELECTRICAL PRODUCTS GROUP ATKINSON BLENKHORN & SAWLE CALVERT CENTRAL ELECTRIC CGIT SYSTEMS N L I R - A - L

AZZ | Central Electric is recognized by utilities for its customer focused and solutions oriented approach to designing and building metal-clad switchgear. Central Electric’s progressive and proactive approach delivers unmatched value to customers through customized designs and Total Quality procedures.

This experience and success serving utility needs has enabled Central Electric to successfully support industrial and commercial applications as well. Our customers include:

• Investor Owned and Public Utilities• Continuous Process / Heavy Industries• Wastewater Treatment Plants• Medical and Educational Institutions• PublicComplexes/LargeOfficeBuildings• Data Centers• Surface Mining Operations

Central Electric’s highly experienced “can-do” team has been designing and build-ing value driven switchgear for over 50 years, supporting virtually any level of technology required. Equipment is designed and tested to meet or exceed all applicable ANSI, IEEE, NEC, NEMA and NFPA Standards, and is manufactured in Central Electric’s ISO 9001 certi-fied facility. To insure the highest degree of continued reliability, a variety of ongoing mechani-cal and electrical tests are periodically performed. Total Quality is the focal point of all activities.

Recognizing the ongoing need to provide for a safer environment for workers and decrease unexpected equipment costs, the power of Central Electric’s “can-do” team was brought to bear on the challenge of an arcing fault inside metal-clad switchgear. The result was an arc resistant metal-clad switchgear design unsurpassed in the industry. Although the probabil-ity of such an arcing fault occurring is low, the cost in terms of safety and damage is rather high when an arcing fault does occur. With their continued commitment to safety and excellence, Central Electric is pleased to introduce our new line of arc-resistant metal-clad switchgear.

EXPERIENCE IN ENGINEERING

CHALLENGETraditional metal-clad switchgear has and continues to provide safe and reliable service. In fact, recent advances in metal-clad switchgear technology have greatly improved the reliability of distribution systems. The occurrence of an arcing fault is the exception not the rule. It can, however, present significantpersonnel safety and equipment damage challenges when one does occur due to a malfunction or human error. In addition, an increased emphasis on workplace safety today has driven the need for safer system planning, training, procedures and products.

Typically an arcing fault can be characterized as a four-stage process:

• Compression Stage – This stage begins at arc inception and continues until a maximum internal pressure is reached within the equipment, typically in terms of milliseconds.

• Expansion Stage – This stage begins when pressure can no longer be contained and venting to the outside starts, once again in terms of milliseconds.

• Emission Stage – During this stage, the arc is in direct contact with outside air as inside air is exhausted through any available relief point. The air volume inside is now being heated to the same temperature as the arc itself. It is at this point when personnel can be directly endangeredbywhateverisbeingexpelled.Thisstagetypicallylastslongerthanthefirsttwo,but still in terms of milliseconds.

• Thermal Stage – This stage can be the most damaging and lasts until the arc is extinguished. Thermal energy emitted heats, melts and vaporizes structure parts and any components within the structure. The greatest degree of damage typically occurs during this stage.

The challenge is to evaluate the potential risk for a specificapplicationand/orlocationtodeterminewhatis needed to insure maximum safety and minimize equipment damage. Risk of injury and/or damage to metal-clad switchgear is usually due to one of the following causes.

•Human error•Mechanical failures• Intrusionbyoutsideinfluencessuchasmice

and snakes•Environmental issues such as dust and

moisture• Insulation failure• Inadequate preventive maintenance

.

CONSIDERATIONSIt is always prudent to take a proactive approach and address potential problem areas in the initial design stages. Preventive measures increase personnel safety as well as minimize potential equipment damage and costly repairs.

•Reduce the risk through system design

•Training personnel with adherence to safety practices

•Devising strict routines for maintenance procedures

•Establishingaflashboundary

•Utilizing very visible warning labels

• Investing in arc-resistant mitigation switchgear

• Implementing other mitigation techniques

.

ARC-RESISTANT METAL-CLAD SWITCHGEARArc-resistant metal-clad switchgear is designed and tested to mitigate the effects and conditions of arcing due to an internal arcing fault. The degree to which this is accomplished depends on what particular accessibility rating the equipment was designed and successfully tested to meet. To make an informed decision, it is imperative:

1. To understand the testing requirements for the degree of protection

2. To be confident that the manufacturer’s designsadequately address different customer preferences and application needs

IEC (International Electrotechnical Commission) firstaddressed the issue followed by EEMAC (Electrical and Electronic Manufacturers Association of Canada). These pioneering efforts were followed by ANSI/IEEE guidelines. All of these efforts were driven primarily by personnel and equipment safety. All three governing bodies have a slightly differentwayof defining the specificdegreesof protection.For the purpose of simplification, ANSI/IEEE C37.20.7descriptions are offered in ascending order of degree of protection provided, with Type 2C (Type 2BC) offering thehighest degree of protection.

Type 1: switchgear with arc-resistant construction at front only

Type 2: switchgear with arc-resistant construction at front, back and sides – survival of maintenance personnel

Type 2B: Type 2 with LV instrument compartment door

Type 2C (or Type 2BC):Type2Bwitharc-resistantbarriersbetween adjacent internal compartments – intended to reduce collateral damage to adjacent compartments and equipment, as well as insuring the safety of maintenance personnel working nearby

.

OTHER MITIGATION TECHNIQUES

Consider other safety and operational techniques that can further protect personnel and help to detectorextinguishanarcflash.

•Reduce the clearing time of circuit breakers•Arcflashmitigationrelays•Optical and current sensors•Remote racking devices•Remote operation of devices•Equipment viewing windows•System grounding methods•Current limiting fuses

.

ROBUST, RELIABLE, PROVENCentral Electric’s robust utility grade metal-clad switchgear has been the standard of excellence in the industry for decades. Their arc-resistant (AR) design is no exception. The engineering team was challenged to provide an arc-resistant design that would offer a safer environment for workers, and minimize damage from the unlikely event of an arcing fault. The result, a proven Type 2C compliant arc-resistant metal-clad switchgear design that reflects the same design synergyand engineering excellence that shaped Central Electric’s reliable product offerings through the years. In concert with Type 2C AR metal-clad switchgear, Central Electric offers a total arc mitigation solu-tion to provide superior protection and minimize risk of errors and injuries for your specific application.

Central Electric’s AR switchgear is available in a wide range of ANSI ratings.

•Voltages: 5kV and 15kV

•Continuous Currents: 1200A, 2000A, 3000A

• Interrupting Rating: 25kA, 31.5kA, 40kA

.

TESTED AND COMPLIANTThe product offering was fully tested and proven at a world class testing facility. It meets or exceeds all appropriate IEEE, ANSI and NEMA requirements. All outdoor switchgear enclosures are designed for structural and seismic requirements based on the installation site zip code.

To insure the highest degree of continued reliability, a variety of mechanical and electrical tests are periodically performed at our in-house test lab. Stringent production verificationtesting, inspection procedures and quality assurance programs further guarantee integrity.

Following lower PT test (bottom right panel of Figure A) - notice unharmed test panels in adjacent (Figure A) and main bus compartments (Figure B), resulting in superior personnel and equipment protection.

Figure A

Figure B

Figure C

.

UTILITY GRADE CONSTRUCTION•11 gauge minimum seam-welded switchgear

structures

•Double-walled switchgear line-up construction•Switchgear modules bolted into outdoor

enclosure

•One-piece enclosure shipment – eliminates fieldreceivingandassemblyissues

•Outdoor enclosure with continuously welded weatherproof seam

•Continuously welded wall and roof panels – eliminates possible leaks

•Removable roof sections - allows for emergency switchgear module replacement

•Nine point visible front door latching mechanism

•Rear mounted breaker bypass switch/paralleling switch design available

•Hinged rear doors

•All base surfaces under coated

•Wide variety of additional standard and optional structural features

•350 MCM cable used in PT compartment to protect faults from propagating into the rear cable section

.

TYPE 2C DESIGNCentral Electric’s arc-resistant metal-clad switchgear design underwent thorough testing to demonstrate successful compliance with the ANSI accredited IEEE C37.20.7 for Type 2C arc-resistant switchgear. Type2Ctestingspecifiesthatarcingdoesnotcauseholes in thefreelyaccessible front,sides,andrear of the enclosure or in the walls separating the compartment in which the arc is initiated from all adjacent compartments. The design was created to support both United States and Canadian customer requirements.

•Maximum personnel protection inside and outside – not just outside•Switchgear survival with minimum damage inside and outside - not just inside•Assembly protection – saving breaker in front with arc incident in rear•Equipment survival in adjacent structures•Single damaged structure removal – not the entire lineup•Less equipment downtime after an arc incident•BreakerandPTpositionviewingwindows•Large 47 inch instrument compartment above breaker•Upper auxiliary compartment with full Type 2C isolation

FollowingMainBreakertest,noticeunharmedLVcontrolsectionandadjacentbreakersections.

.

Front View - Outdoor Arc Resistant Switchgear

LOW PROFILE DESIGN•Spaceefficient

•Lowprofileplenum–fitsinstandardoutdoorenclosure(10footceilingheight)

•No complicated assembly of plenum on site

•No additional shipping concerns – most designs fall within normal outdoor switchgear shipping limits – no need for extra permitting, flagging, specialrouting or escorts

•Forindoordesigns,arc-resistantswitchgearfitsintoastandardheightelectricalroom – no excessive height requirements, the result of a plenum design less than 20 inches high

.

PATENT PENDING FEATURES

•Frontdoorlatchallowsvisibleconfirmationofproper latching – eliminates safety concerns

•Dynamic door vent latching – provides for proper airflowduringnormaloperatingconditionswhileisolating compartments during arcing events

•Plenumflapmechanism-providesequipmentventilation while maintaining Type 2C integrity

•Upper auxiliary compartment with full Type 2C isolation

.

OVERALL ARC MITIGATION SOLUTIONCentral Electric offers a comprehensive arc mitigation solution to address the needs of a customer’s specific application. An arc flash study can be performedwithrecommendations made relative to actions that can be taken to meet a particular facility’s unique requirements. In addition to the utilization of arc-resistant metal-clad switchgear that provides maximum personnel protection with a minimum of damage as a result of an arcing fault, other proactive actions should be considered, such as:

•Perform hazard/risk evaluation procedure

•Establishflashprotectionboundaries

•Label Warnings and Cautions for equipment

•Light and current sensing relay devices

•Fast clearing 3-cycle breakers

•Closed door racking of breakers/PTs/CPT fuse drawers

•Remote close/trip breakers

•Reduce available fault current

•Viewing windows

•Remote relay panels

•Door/firewallbetweenswitchgearroomandrelaypanelarea

• Interlocked rear switchgear doors based on breaker position

.

WHY TYPE 2C FROM CENTRAL ELECTRIC

Once the decision has been made that something beyond standard metal-clad switchgear is necessary foryourspecificfacility,considerthelong-termbenefitsderivedfromselectingCentralElectricforyourindoor or outdoor application. All solutions build upon years of extensive engineering knowledge and applications in the utility market segment, and feature Central Electric’s utility grade Type 2C arc-resistant metal-clad switchgear, supplemented with the use of other uniquely chosen arc mitigation techniques.

CentralElectric’srigidlyconstructedType2C(2BC)arc-resistantswitchgearisprecisioncraftedtoprovide for:

•Stringent utility grade applications

•The greatest degree of personnel safety for the operator

•A minimum of immediate and peripheral equipment damage

•Limited downtime after an arcing event

•Reduced liability concerns

•Compact space design

• Easy cost effective transportation

•No special or labor intensive site installation requirements

• Industry compliance based on rigorous testing

•Extended Durability

•Leading-edge features

Top View - Outdoor Arc Resistant Switchgear

.

FollowingaMainBustest,noticeunharmedcablecompartmentandmainbreakersections.

.

ControlCompartmentoverBreaker PTCompartmentoverBreaker

PT Compartment over PT Compartment PT Compartment over Fuse Compartment

AVAILABLE CONFIGURATIONS

.

TieBreaker/BusConfiguration TieBreaker/TransitionBusConfiguration

PTCompartmentoverTieBreaker RearMountedSwitch-BreakerBypassSwitchw/TransferBus(2Binrearsection)

NOTES

NOTES