Article 450 - Transformers

Article 450 - TransformersThomas A. Domitrovich, P.E.National Application EngineerLEED Accredited ProfessionalEaton Corporation Electrical Group1000 Cherrington ParkwayMoon Township, PA 15108Cell: 412-716-1475email: thomasadomitrovich@eaton.comTim McBride, P.E.Application Engineer 2008 Eaton Corporation. All rights reserved.

The TransformerAn electrical device thattransfers energy by magneticinduction from one circuit toanother.Usually the voltage and currentare transformed from one levelto another.22

The Transformer – Basic ComponentsDry-Type Transformer Example Primary & SecondaryWindings Core Frame Enclosure Ventilation33

Transformer Types – Sampling Step – Up Step – Down Autotransformer Isolation Transformer Single – Phase Polyphase Harmonic Transformers Instrument Transformers44

Transformer Locations / Applications Utility Supply To Facilities Commercial, Industrial, Residential and More Power Distribution Equipment Switchgear, Switchboards Utilization Equipment Control Power Motor Control Centers, Industrial Control Panels Instrumentation Applications Metering and Relaying55

IndustrialControlPanelOCPDOCPDOCPDOCPDMOCPDOCPD66

UtilityGOCPDOCPD Main Incoming 7

CPDOCPDOCPDOCPDMOCPDOCPD88

UtilityGOCPDOCPDPower DOCPD99

UtilityGOCPDOCPDControl 10

UtilityGOCPDOCPDTransformers Are A Very Important Part ofThe Power Distribution ControlPanelOCPDOCPDOCPDOCPDMOCPDOCPD1111

Transformer Basics 2008 Eaton Corporation. All rights reserved.

3-Phase Transformers Incorporate three sets of windings Can be wired Delta or Y on primary or secondary Can be grounded or ungrounded 1-Phase Transformers1313

Three Phase Delta-WyeVll VΦ14Vll - 3*VΦ14VΦ14

Basic Transformer Principle A voltage and current in the primary coil magnetize the iron core. The magnetic field in the core induces a voltage and current in the secondary 1515

Transformer ExamplePrimaryCoreSecondaryV1N1 V1 480 voltsV2 120 voltsV2N2A2N1 N2 100N1 400A1N2V1A2 A1 52 ampsN1 - # turns (primary)A2 V2208 ampsV1-primary voltageN2 - # turns (secondary) V2-secondary voltageA1A1-primary currentA2-secondary current1616

KVAKVA is the transformer’s capacity or loadthat it can handle.Three PhaseSingle PhaseKVA Volts * Amps1000KVA 3*VoltsØ * AmpsØ1000-orKVA VoltsL * AmpsL * 1.7321000171717

KVA ExampleCustomer’s load - three phase, 480 volts, 60 Hz, 100 ampsKVA Volts * Amps * 1.7321000KVA 480X100X1.7321000KVA 83.14181818

FLA & Isc ExampleFull Load Amps - three phase, 480 volts, 60 Hz, 300 kVAAmps 1000* kVA1.732 *VoltsAmps 300 X 1000480X 1.732Amps 361 AIsc FLA%Z19 361 6278 A.05751919

Taps Correct for high or low input voltage conditionsso the transformer will still provide its ratedoutput voltage Connection off of the primary winding Usually in 2.5% or 5.0% increments FCAN - Full Capacity Above Nominal FCBN - Full Capacity Below Nominal202020

TapsCorrect for high or low input voltage conditionsso that transformer will still provide its ratedoutput voltage.Connection off the primary winding,usually in 2.5% or 5.0% increments.FCAN - Full Capacity Above NominalFCBN - Full Capacity Below Nominal212121

Taps Example 2 @ 2-1/2% FCAN- 4 @ 2-1/2% FCBN480V120V222222

Tap Example – Low Primary VChange The Turns 61120232323

Insulation Systems andTemperature RiseTemperature Rise5580115150Hot ion Class/Limiting TemperatureFormer DesignationTemperatures in degrees centigrade242424

Auxiliary Cooling Liquid filled transformersFan cooling - 15%750 kVA to 2000 kVAFan cooling - 25%2500 kVA and above Dry type transformersFan cooling - 33%25All ratings2525

Ratings - Liquid Filled Fluid Filled65 C Rise26OA(BaseRating)FA(OA x 1.15 2500 kVA,OA x 1.252500kVA & 5/65 C RiseOA55 COA 65 COA x 1120158022402800FA 55 C(OA x 1.15FA 65 C 2500 kVA,OA x 1.252500kVA & )OA 65C x 1.15 2500 kVA,OA 65C x 1.252500kVA & ----8621150172523003125----96612881932257635002626

Ratings - Cast Coil100 C Rise2780/100 C RiseAA 100(Base)FA(AA100 x1.33)AA 80(Base)AA 100(AA80 x1.125)FA 100(AA100 502813--750112515002250300037502727

Ratings - Dry Type150 C Rise115/150 C RiseAA150C(Base)FA(AA150 x1.33)AA115 C(Base)AA 150 C(AA115 x1.15)FA 150 C(AA150 x 0028754607671151153323003067383380/115 C Rise28AA80 (Base)AA115 (AA80 x 0295080/150 C RiseFA115 (AA115 x1.33)AA80 C(Base)AA150 C(AA80 x1.35)FA150 C(AA150x 360045002828

Insulation LevelsKv 0757595959595125150LiquidFilledTransf.LV(600 Max).Vent. DryTransf.HVVent. DryTransf.LV(600 Max.)Cast CoilTransf.HVCast CoilTransf.LV(600 01010101010101010102929

Sound LevelsTable 6 - NEMA TR-1 Maximum Sound Level Comparison USTsLiquid-TypesDry-TypeskVA(All Fluids)VPI,VPE,CASTOAOA/FAAAAA/FA301 to 50056676067501 to 70057676267701 to 1000586764671001 to 1500606765681501 to 2000616766692001 to 2500626768712501 to 300063676871303030

Transformer Standards 2008 Eaton Corporation. All rights reserved.

Transformer StandardsUL 506“Specialty Transformers”UL 1561 “Dry-Type General Purpose and Power Transformers”UL 1562 ‘‘Transformers, Distribution, Dry-Type – Over 600 Volts,’’UL 2161 “Neon Transformers and Power Supplies”3232

Transformer StandardsUL 506“Specialty Transformers”1.1 These requirements cover ignition transformers for use with gasburners and oil burners and specialty step-up transformers used inapplications such as insect electrocuting. Transformers incorporatingovercurrent or over-temperature protective devices, transient voltage surgeprotectors, or power factor correction capacitors are also covered by theserequirements. These transformers are intended to be used in accordancewith the National Electrical Code, NFPA 70.3333

Transformer StandardsUL 1561 “Dry-Type General Purpose and Power Transformers”These requirements cover:a) General purpose and power transformers of the air-cooled, dry,ventilated, and non-ventilated types to be used in accordance with theNational Electrical Code, ANSI/NFPA 70. Constructions include step up,step down, insulating, and autotransformer type transformers as well as aircooled and dry-type reactors orb) General purpose and power transformers of the exposed core, aircooled, dry, and compound-filled types rated more than 10 kVA to be usedin accordance with the National Electrical Code, ANSI/NFPA 70.Constructions include step up, step down, insulating, and autotransformertype transformers as well as air-cooled, dry, and compound-filled typereactors.3434

Transformer StandardsUL 1562 ‘‘Transformers, Distribution, Dry-Type – Over 600 Volts,’’1.1 These requirements cover single-phase or three-phase, dry-type,distribution transformers, including solid cast and resin encapsulatedtransformers. The transformers are provided with either ventilated or nonventilated enclosures and are rated for a primary or secondary voltage from601 to 35000 V.3535

Transformer StandardsUL 2161“Neon Transformers and Power Supplies”1.1 This standard applies to transformers and power supplies, including those intended to beconnected to a Class 2 source of supply, that provide the voltage and ballasting for neon andcold-cathode tubing (electric-discharge tubing) consisting of electrodes and gas such as neon,mercury, helium, argon, and similar gases, enclosed in glass. Neon transformers and powersupplies for use in signs and outline lighting are intended to be used in accordance with Article600 of the National Electrical Code, NFPA 70. Cold-cathode supplies identified for use only incold-cathode lighting systems are intended to be used in accordance with Article 410 of theNational Electrical Code.1.2 Neon transformers and power supplies covered by this standard are designated by theirconstruction and intended use as specified in Table 1.1.3636

Transformer StandardsUL 2161“Neon Transformers and Power Supplies”3737

Transformers and The NEC 2008 Eaton Corporation. All rights reserved.

Transformers and The NEC Article 450 “Transformers andTransformer Vaults (IncludingSecondary Ties)” 450.1 Scope. This article coversthe installation of all transformers.The NEC Has An Entire Article, Article 450, Dedicated To Transformers3939

Transformers and The NEC450.1 Scope. This articlecovers the installation of alltransformers.Exceptions1. Current transformers.2. Dry-type transformers that constitute a component partof other apparatus and comply with the requirements forsuch apparatus.3. Transformers that are an integral part of an X-ray, highfrequency, or electrostatic-coating apparatus.4. Transformers used with Class 2 and Class 3 circuits thatcomply with Article 725.5. Transformers for sign and outline lighting that complywith Article 600.Exceptions Illustrate Other ArticlesImportant to Proper Application ofTransformers6. Transformers for electric-discharge lighting that complywith Article 410.7. Transformers used for power-limited fire alarm circuitsthat comply with Part III of Article 760.8. Transformers used for research, development, ortesting, where effective arrangements are provided tosafeguard persons from contacting energized parts.Don’t Stop At Article 450Understand The Application4040

Transformers and The NECArticle 725: Class 1, Class 2, and Class 3Remote – Control, Signaling, and Power-LimitedCircuits450.1 Scope. This articlecovers the installation of allArticle 600: Electric Signs and Outline Lightingtransformers.Article 410: Luminaires, Lampholders, andLampsArticle 760: Fire Alarm SystemsExceptions1. Current transformers.2. Dry-type transformers that constitute a component partof other apparatus and comply with the requirements forsuch apparatus.3. Transformers that are an integral part of an X-ray, highfrequency, or electrostatic-coating apparatus.4. Transformers used with Class 2 and Class 3 circuits thatcomply with Article 725.5. Transformers for sign and outline lighting that complywith Article 600.Exceptions Illustrate Other ArticlesImportant to Proper Application ofTransformers6. Transformers for electric-discharge lighting that complywith Article 410.7. Transformers used for power-limited fire alarm circuitsthat comply with Part III of Article 760.8. Transformers used for research, development, ortesting, where effective arrangements are provided tosafeguard persons from contacting energized parts.Don’t Stop At Article 450Understand The Application4141

Protection – Table 450.3(A)PRIMARY OVER 1000 VOLTSAny LocationIMPEDANCENot More Than 6%PRIMARY PROTECTION600% - Circuit Breaker300% - FuseSeconday 1000Volts300% - Circuit Breaker250% - FuseSeconday 1000Volts or Less125% - Circuit Breaker42125% - Fuse4242

Protection – Table 450.3(A)PRIMARY OVER 1000 VOLTSAny LocationIMPEDANCEMore Than 6% & Not More Than10%PRIMARY PROTECTION400% - Circuit Breaker300% - FuseSeconday 1000Volts250% - Circuit Breaker225% - FuseSeconday 1000Volts or Less125% - Circuit Breaker43125% - Fuse4343

Protection – Table 450.3(A)PRIMARY OVER 1000 VOLTSSupervised LocationIMPEDANCENot More Than 6%PRIMARY PROTECTION600% - Circuit Breaker300% - FuseSeconday 1000Volts300% - Circuit Breaker250% - FuseSeconday 1000Volts or Less250% - Circuit Breaker44250% - Fuse4444

Protection – Table 450.3(A)PRIMARY OVER 1000 VOLTSSupervised LocationIMPEDANCEMore Than 6% & Not More Than10%PRIMARY PROTECTION400% - Circuit Breaker300% - FuseSeconday 1000Volts250% - Circuit Breaker225% - FuseSeconday 1000Volts or Less250% - Circuit Breaker45250% - Fuse4545

Protection – Table 450.3(A)PRIMARY OVER 1000 VOLTSSupervised LocationIMPEDANCEAnyPRIMARY PROTECTION300% - Circuit Breaker250% - FuseSeconday 1000VoltsN/A - Circuit BreakerN/A - FuseSeconday 1000Volts or LessN/A - Circuit Breaker46N/A - Fuse4646

Protection – Table 450.3(A)Next Standard Rating6 Disconnect Rule – Single LocationTotal Rating Not to Exceed AllowedValue of Single Over Current Device474747

Protection – Table 450.3(B)PRIMARY 1000 VOLTS & LESSPRIMARY PROTECTION ONLY48Currents of 9 Amps or More125%Currents Less Than 9 Amps167%Currents Less Than 2 Amps300%4848