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SWITCHGEAR BIG GRAY BOXES SWITCHBOARD

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Why Different Standards? ANSI vs UL

Feature Switchboard Switchgear Environment Environment

History HistorySegment Residential/Commercial Utility/IndustrialConcerns Safety/Fire Protection Safety/Fire/ Protection

Personnel/Property Protection

Process Protection and Continuation

Certification Many small suppliers-Third Party (UL) required to assure requirements

Few, Large suppliers User-Specifier Standards (Self Certified) Industry Groups (ANSI/IEEE)

(Third Party Certification since 1982)

Design Verification

"Paper Design" or Test Verification

Test Verification Required

Maintenance Minimum or None Permitted (Often Necessary!)

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Standards Comparison

Feature Switchboard Switchgear

Structure UL 891 ANSI C37.20.1(UL 1558)

Devices UL 489(MCCB)

ANSI C37.13(LVPB)(UL 1066)

UL 977(BOLT-LOC)

UL 98(Fused Switch)

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Standards Comparison (cont.)

Feature Switchboard Switchgear

Qualification Analysis or Test Must Test

Device Mtg. Fixed or DO DO Only

Bus Sizing Design or Test Heat RiseTest

InternalBarriers

Optional-Mfg.Determines

BreakerCompt.-Defined(Others-Optional

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Comparison (cont.)

Feature Switchboard Switchgear

Short TimeWithstandRating

Not Defined(Mfgr.Establishestest)

PreciselyDefined

ANSI Test:.5 sec closed15 sec open.5 sec closedNo trip unit(aux trip)

Switchgear has Defined Short Time Withstand Ratings!

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“Practice” Comparison

Feature Switchboard SwitchgearMaintenance(Industry

Practice)

VariousPractices; non-maintainablebreakers and tripunits acceptable

Permitted to maintainequipment operatingparameters

Breaker can be rebuilt;contacts and trip unitsfield replaceable

Switchgear maintenance permitted (not required by standard).

Switchboard maintenance often not allowed.

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Side View

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Rear View

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Insulated Case vs Molded Case

Insulated Case

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Old Vs New

Insulated Case UL 1066 IRON FRAME ANSI

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Insulated Case vs Molded Case

Molded Case

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Advantages of Insulated Case Vs Iron Frame

Smaller footprintMore reliable (Modular Design with Fewer Parts)Higher interrupting ratings Higher withstand ratings (30 Cycles)Reduced maintenanceElectronic Trip Units

Field Installable Trip UnitsCommunicationsPower monitoring (2.5% Accuracy)

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Mechanical Construction

• Breaker Frames– Small :

• 800A ANSI, • 1200A UL, • 1600A IEC

– Medium : – 800 to 3200A ANSI, – 800 to 3000A UL, – 800 to 4000A IEC

– Large : – 4000 to 5000A ANSI, – 4000 to 6000A UL,– 4000 to 6300A IEC

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Organic Vs Iron Frame

• Very strong and lightweight• Provides good insulation, isolation,

and dielectric• Molded to support and hold internal

parts with no adjustments• Fewer parts reduces complexity of

assembly and maintenance

The thermoset material of the organic case has several advantages:

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Organic Vs Iron Frame

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A

LCD ammeter LED Bargraph

P

LCD All functions

Display type

H

LCD All functions

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UL 891 Switchboards

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Switchboards

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Switchboards

• Typical Switchboard Ratings

•5000 A Mains and Bus•1200 A and smaller group mounted•Greater than 1200A Individally mounted Fixed or Drawout•Front Connected•UL 891 Gear•UL 489 Breakers

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“Hybred UL 891 Switchboards”

• Mix Insulated Case and Molded Case• Individially mounted

– Front Connected– Rear Connected

• Individually mounted – Drawout– Fixed

• Group Mounted and Drawout• Fusible and Circuit Breaker• No requirement for isolation or

– Barriers

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SWITCHGEAR BIG GRAY BOXES SWITCHBOARD