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Design Guide DG009001ENEffective February 2020Low-voltage power distribution and control systems Transformers Dry-type distribution transformers—general purposeContentsGeneral Purpose Ventilated Transformers. . . . . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19.1-219.1-219.1-319.1-10General Purpose Ventilated TransformersWith Integral Breakers . . . . . . . . . . . . . . . . . . . . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19.1-1119.1-1119.1-1219.1-13General Purpose Encapsulated Transformers. . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19.1-1419.1-1419.1-1519.1-20Application Information . . . . . . . . . . . . . . . . . . . . . . . .Transformer Selection . . . . . . . . . . . . . . . . . . . . . . . . .Standards and Certifications . . . . . . . . . . . . . . . . . . . .Glossary of Transformer Terms. . . . . . . . . . . . . . . . . . .The Energy Policy Act of 2005. . . . . . . . . . . . . . . . . . .Frequently Asked Questions About Transformers . . . .19.1-2219.1-2219.1-2419.1-2519.1-2819.1-29More about this productEaton.com/transformersComplete library of design guidesEaton.com/designguides
Dry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersOverviewEaton’s family of energy-efficientventilated transformers meets DOE 2016efficiency requirements and federal energyefficiency laws mandated by the EnergyPolicy Act of 2005 and 10 CFR Part 431(2016). Energy-efficient transformers areespecially designed to have low no-load(core) losses; minimum efficiencylevels have been established for thesetransformers when loaded at 35% oftheir full load capacity. Available 600 Vdistribution transformers installed inthe United States are required to meetthese energy efficiency requirements.General purpose DOE 2016 transformers,single-phase 15–100 kVA and three-phase15–300 kVA, are manufactured in seismiccertified (including OSHPD) NEMAT Type 2enclosures with optional weathershieldsto make the enclosure NEMA 3R; wallmounting is available up to 112.5 kVA(1400 lb maximum weight). Coils arewound with aluminum or copperconductor and 220 C insulation materials.The transformers are available withtemperature rise options of 150 C, 115 Cor 80 C, NEMA ST-20 audible sound levels,and 60 or 50 Hz. Installation of energyefficient transformers may help facilitiesearn points toward LEEDT certificationfrom the U.S. Green Building Council.Note: Three-phase general purposetransformers are available with integralcircuit breakers to save installation time,footprint, and reduce arc flash incidentenergy at downstream panel.Design Guide DG009001ENEffective February 202019.1-2Wall-mounting capability up to 1400 lb(equivalent to a typical 150 kVA threephase ventilated transformer). Wallmounting kits WMB04 and WMB05 areOSHPD certifiedEaton voluntarily verifies the 2016efficiencies with UL. Customers canbe sure that Eaton-manufacturedtransformers meet the DOE 2016minimum required efficiencies.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersTechnical DataGeneral Construction Featuresof General Purpose VentilatedTransformers Rated 600 V and belowEaton’s single-phase and three-phasegeneral purpose dry-type ventilatedtransformers are of the two-windingtype, self-cooled, and are available in awide variety of primary and secondaryvoltage combinations.Eaton’s transformers are designed,manufactured and tested in accordancewith all of the latest applicable ANSI,NEMA and IEEE standards. All 600 Vclass ventilated transformers with ratingsthrough 1000 kVA are UL listed andbear the UL label. Open core and coilassemblies are UR labeled products.These transformers are designed forcontinuous operation at rated kVA for24 hours a day, 365 days a year, withnormal life expectancy as definedin ANSI C57.96.Efficiency validation: Eaton-manufacturedtransformers in compliance with 10 CFRPart 431 (2016), “DOE 2016 efficient” bearthe UL Energy Efficiency Verification Markto confirm that the transformer meets theenergy efficiency requirements set forthin federal law 10 CFR Part 431.Insulation SystemThe design life of transformers havingdifferent insulation systems is the same;the lower temperature systems aredesigned for the same life as the highertemperature systems.Eaton ventilated transformers,regardless of their temperature rise,are manufactured using a 220 Cinsulation system. Requiredperformance is obtained withoutexceeding the insulation systemrating at rated temperature rise ina 40 C maximum ambient, withan average ambient temperatureof 30 C over a 24-hour period.Transformers manufactured with 220Cinsulation system meet the requirementsof NEC 450.21(b) Exception No.2. It is notnecessary to install them in a special,fire-resistant room.All insulation materials used areflame-retardant and do not supportcombustion as defined in ASTMStandard Test Method D635.Effective February 202019.1-3Core and Coil AssembliesTapsThe transformer core is constructed usinghigh-grade, non-aging, silicon steel withhigh magnetic permeability, and lowhysteresis and eddy current losses.Maximum magnetic flux densities aresubstantially below the saturation point.The transformer core volume allows forefficient transformer operation at 10%above the nominal tap voltage. The corelaminations are tightly clamped andcompressed. Coils are wound of electricalgrade aluminum or copper, and are ofcontinuous wound construction. The BIL(basic impulse level) for all 600 V-classwindings is 10 kV. The core and coilassembly is installed on neoprenevibration-absorbing pads.Primary taps are available on mostEaton ventilated transformers toallow compensation for sourcevoltage variations.Ventilated transformers with wyeconnected secondaries have the neutralbrought out to a separate XO terminalor busbar.The core and coil assembly is groundedto the transformer enclosure by means ofa visible flexible copper ground strap. Thecopper ground strap is sized per the NECto be a grounding conductor.Eaton three-phase DOE 2016 efficienttransformers are provided with a bondingground bar attached to the bottom panelfor compliance with NEC 450.10(A).Transformer core and coil covered witha fungus-resistant varnish to seal outmoisture and other contaminants, andprevent the growth of fungus.Electrostatic ShieldingThere are no industry standards forelectrostatic shield performance. Eatonmanufactured transformers have beentested by an independent laboratory tomeet the following attenuation levels:Winding TerminationsPrimary and secondary windings areterminated in the wiring compartment.Encapsulated units have copper leadsor stabs brought out for connections.Ventilated transformers have leadsbrought out to aluminum or copper padsthat are pre-drilled to accept Cu/Al lugs.Aluminum-wound transformers havealuminum pads; copper-woundtransformers have copper pads. Lugs arenot supplied with Eaton transformers;however, lug kits are available asa field-installed accessory. Eatonrecommends external cables be rated90 C (sized at 75 C ampacity) forencapsulated designs and rated 75 Cfor ventilated designs.Series-Multiple WindingsSeries-multiple windings consist of twosimilar coils in each winding that can beconnected in series or parallel (multiple).Transformers with series-multiplewindings are designated with an “x” ora “/” between the voltage ratings, suchas voltages of “240 x 480” or “120/240.” Ifthe series-multiple winding is designatedby an “x,” the winding can be connectedonly in series or parallel. With a “/”designation, a mid-point also becomesavailable in addition to the series orparallel connection. As an example, a240 x 480 winding can be connected foreither 240 (parallel) or 480 (series). A120/240 winding can be connected foreither 120 (parallel) or 240 (series), or240 with a 120 mid-point.When tested per MIL-Std-220A, Methodof Insertion Loss Measurement, withmatched impedance no load technique:1. Common mode noise attenuation:Minus 80 dBA minimum at 0.1 kHz to1.5 kHz; minus 55 dBA minimum at1.51 kHz to 100 kHz.2. Normal mode (Transverse mode)noise attenuation: Minus 35 dBAminimum at 1.5 kHz to 10 kHz.Primary to Secondary Capacitance of24.74–18.06 picofarads on the range100–20 kHz.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-4EnclosuresSound LevelsThe transformer enclosure is made ofheavy-gauge steel and is finished usinga continuous process of degreasing,cleaning and phosphatizing, followedby electrostatic deposition of a thermo setting polyester powder coating andsubsequent baking. The coating color isANSI 61 and is UL recognized for outdooruse. In compliance with NEMA ST-20,Eaton’s ventilated transformers aredesigned such that the maximumtemperature on the top of the enclosuredoes not exceed 50 C rise above theambient temperature.All transformers emit some audiblesound due mainly to the vibrationgenerated in their core by alternatingflux. NEMA ST-20 defines the maximumaverage sound levels for transformers.For ventilated transformers, the enclosureconstruction is ventilated, drip-proof,NEMA 2, with lifting provisions.All ventilation openings are protectedagainst falling dirt. Proper installationof weathershields on ventilatedtransformers makes the enclosureNEMA 3R rated and suitable foroutdoor use.To ensure proper ventilation and coolingof the transformer, follow manufacturer’srecommended clear ances aroundventilation openings.Installation ClearancesEaton’s transformers should be installedwith a minimum clearance around thetransformer enclosure to preventaccidental contact with flammable orcombustible materials. The minimumrequired clearance from the back panelvaries by transformer design. Many smallkVA ventilated transformers (150 kVA andsmaller) require just 2 inches of clearance,while larger kVA transformers require6-inch clearance or more. Minimuminstallation clear ances are stated on thenameplate of all transformers.The NEC requires a minimum of 36 inchesclearance in front of the transformer forsafe installation and maintenance. Careshould be taken to avoid restricting theairflow through the bottom of thetransformer.Transformers should be located in areasnot accessible to the public.All Eaton ventilated transformers aredesigned to have audible sound levelslower than those required by NEMA ST-20(2014). However, consideration should begiven to the specific location of atransformer and its installation tominimize the potential for soundtransmission to surrounding structuresand sound reflection. Installation andambient conditions at a specific locationcan result in field-measured audiblesound levels as much as 15 dBA greaterthan those levels measured in a soundproof chamber. The following installationmethods should be considered:1. If possible, mount the transformeraway from corners of walls or ceilings.For installations that must be near acorner, use sound-absorbingmaterials on the walls and ceiling ifnecessary to eliminate reflection.2. Provide a solid foundation formounting the transformer and usevibration dampening mounts if notalready provided in the transformer.Eaton’s ventilated transformerscontain a built-in vibration dampeningsystem to minimize and isolate soundtransmission. However, supplementalvibration dampening mounts installedbetween the floor and the transformermay provide additional sounddampening.3. Make electrical connections to thetransformer using flexible conduit.4. Locate the transformer in anarea where audible sound is notoffensive to building inhabitants.5. If a transformer is going to be installedin a location where the audible soundcould be objectionable, considerinstalling a transformer specificallydesigned to have reduced soundlevels. Eaton offers manytransformers with a sound reductionup to 5 dB below NEMA ST-20 limits.Table 19.1-1. NEMA ST-20 (2014) Maximum Audible Sound Levels for 600 V Class Transformers (dBA)EquivalentWinding kVA RangeAverage Sound Level, DecibelsSelf-Cooled VentilatedSelf-Cooled SealedABCK Factor 1K Factor 4K Factor 9K Factor 13K Factor 20Forced Air WhenFans RunningD3.00 and below3.01 to 9.009.01 to 15.0040404540404567676745455015.01 to 30.0030.01 to 50.0050.01 to 75.0045455045485367676750505575.01 to 112.50112.51 to 150.00150.01 to 225.00505055535358676767555557225.01 to 300.00300.01 to 500.00500.01 to 700.00700.01 to 1000.0055606264586365676767676757596163Greater than 1000Consult factoryNote: Consult factory for nonlinear requirements exceeding a K-factor rating of 20. When the fans arenot running, columns A and B apply. Sound levels are measured using the A-weighted scale (dBA).EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-5Applicable StandardsOperation600 V-class ventilated transformersare manufactured per the followingstandards:Eaton’s ventilated transformers aredesigned for continuous operation atrated kVA for 24 hours a day, 365 days ayear, with normal life expectancy asdefined in ANSI C57.96.UL 1561 NEMA ST-20 ANSI C57.12.01 IEC 60726 for CE-marked ventilatedmodels Standard Production TestsThe following production tests areperformed as standard on all Eatontransformers, prior to shipment:1. Ratio tests at the rated voltageconnection and at all tap connections.2. Polarity and phase relation tests onthe rated voltage connection.Short-term overload capacity is designedinto transformers, as required by ANSI.Ventilated transformers will deliver 200%of nameplate load for 30 minutes; 150%of nameplate load for 1 hour; and 125%of nameplate load for 4 hours withoutbeing damaged, provided that a constant50% load precedes and follows theoverload. Refer to ANSI C57.96-01.250for additional limitations.Note: Continuous overload capacity is notdeliberately designed into transformers. Thedesign objective is to be within the allowablewinding temperature rise at nameplate fullload capacity.However, because Eaton’s ventilatedtransformers are manufactured usinga 220 C insulation system, 115 Cand 80 C low temperature risetransform ers can be operated as 150 Crise transformers. The excess thermalcapacity of these low temperaturerise transformers allows a 115 Ctrans former to be operated as a 150 Crise transformer and overloaded by15% of its nameplate kVA withoutcompromis ing the normal life of thetransformer. Likewise, an 80 C risetransformer operated as a 150 C risetransformer is capable of a constant30% overload without compromising thenormal life expectancy of the transformer.3. Applied potential tests.4. Induced potential tests.5. No-load and excitation currentat rated voltage on the ratedvoltage connection.Table 19.1-2. Rated Line Amperes for kVA and Voltages of Single-Phase TransformerskVARatingRated Line 50333Note: Line Current (kVA x 1000)/Line Voltage.Table 19.1-3. Rated Line Amperes for kVA and Voltages of Three-Phase TransformerskVARatingRated Line 80.4240.6104.1138.890.2120.3Note: Three-Phase Line Current (kVA x 1000)/(Line Voltage x 1.732).EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-6Table 19.1-4. Typical Data for 480 V Class DOE 2016 Efficient Dry-Type Transformers, Aluminum Wound akVAFrame bWeightLosses in WattsEfficiency (T Rise 20 ºC)NoLoad25%Totalat Rise 20 ºC50%% Regulation75%FullLoad100%PF80%PF% Imp.T Rise 20 ºCXT Rise 20 ºCRT Rise 20 ºCSoundLeveldB (perNEMAST-20)Efficiencyat 35%Load 75 ºCInrushPracticalMax.Type DS-3 150 C Rise DOE 2016 Efficient cccccccccccccType DS-3 115 C Rise DOE 2016 Efficient cccccccccccccccType DS-3 80 C Rise DOE 2016 Efficient cccccccccccccccType DT-3 150 C Rise DOE 2016 Efficient cccccccccccccccccc5007501000abcTypical values for aluminum windings. Refer to Page 19.1-8 for typical data for copper windings. Up-to-date design data is available at www.eaton.com.For transformer dimensions by frame, see Page 19.1-10.Contact local Eaton representative.Note: Performance data is based upon 480 V delta primary and a 208Y/120 V secondary for three-phase transformers; 240 x 480 V primary and a 120/240 Vsecondary for single-phase transformers. Refer to Eaton for 5 kV class information. All data is subject to future revision.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-7Table 19.1-14. Typical Data for 480 V Class DOE 2016 Efficient Dry-Type Transformers, Aluminum Wound a (Continued)kVAFrame bWeightLosses in WattsEfficiency (T Rise 20 ºC)NoLoad25%Totalat Rise 20 ºC% Regulation50%75%FullLoad100%PF80%PF% Imp.T Rise 20 ºCXT Rise 20 ºCRT Rise 20 ºCSoundLeveldB (perNEMAST-20)Efficiencyat 35%Load 75 ºCInrushPracticalMax.Type DT-3 115 C Rise DOE 2016 Efficient cccccccccccccccccc5007501000Type DT-3 80 C Rise DOE 2016 Efficient cccccccccccccccccc3005007501000abcTypical values for aluminum windings. Refer to Page 19.1-8 for typical data for copper windings. Up-to-date design data is available at www.eaton.com.For transformer dimensions by frame, see Page 19.1-10.Contact local Eaton representative.Note: Performance data is based upon 480 V delta primary and a 208Y/120 V secondary for three-phase transformers; 240 x 480 V primary and a 120/240 Vsecondary for single-phase transformers. Refer to Eaton for 5 kV class information. All data is subject to future revision.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-8Table 19.1-5. Typical Data for 480 V Class DOE 2016 Efficient Dry-Type Transformers, Copper Wound akVAFrame bWeightLosses in WattsEfficiency (T Rise 20 ºC)NoLoad25%Totalat Rise 20 ºC% Regulation50%75%FullLoad100%PF80%PF% Imp.T Rise 20 ºCXT Rise 20 ºCRT Rise 20 ºCSoundLeveldB(perNEMAST-20)Efficiencyat 35%Load75 ºCInrushPracticalMax.Type DS-3 150 C Rise DOE 2016 Efficient ccccccccccccType DS-3 115 C Rise DOE 2016 Efficient cccccccccccccccccType DS-3 80 C Rise DOE 2016 Efficient cccccccccccccType DT-3 150 C Rise DOE 2016 Efficient cccccccccccccccccccccccccccc5007501000abcTypical values for copper windings. Refer to Page 19.1-6 for typical data for aluminum windings. Up-to-date design data is available at www.eaton.com.For transformer dimensions by frame, see Page 19.1-10.Contact local Eaton representative.Note: Performance data is based upon 480 V delta primary and a 208Y/120 V secondary for three-phase transformers; 240 x 480 V primary and a 120/240 Vsecondary for single-phase transformers. Refer to Eaton for 5 kV class information. All data is subject to future revision.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-9Table 19.1-5. Typical Data for 480 V Class DOE 2016 Efficient Dry-Type Transformers, Copper Wound a (Continued)kVAFrame bWeightLosses in WattsEfficiency (T Rise 20 ºC)NoLoad25%Totalat Rise 20 ºC% Regulation50%75%FullLoad100%PF80%PF% Imp.T Rise 20 ºCXT Rise 20 ºCRT Rise 20 ºCSoundLeveldB(perNEMAST-20)Efficiencyat 35%Load75 ºCInrushPracticalMax.Type DT-3 115 C Rise DOE 2016 Efficient cccccccccccccccccccccccccccc5007501000Type DT-3 80 C Rise DOE 2016 Efficient pical values for copper windings. Refer to Page 19.1-6 for typical data for aluminum windings. Up-to-date design data is available at www.eaton.com.For transformer dimensions by frame, see Page 19.1-10.Contact local Eaton representative.Note: Performance data is based upon 480 V delta primary and a 208Y/120 V secondary for three-phase transformers; 240 x 480 V primary and a 120/240 Vsecondary for single-phase transformers. Refer to Eaton for 5 kV class information. All data is subject to future revision.EATON www.eaton.com
Design Guide DG009001ENDry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated TransformersEffective February 202019.1-10DimensionsFigure 19.1-1. Enclosure Dimensional Drawings—Ventilated TransformersTable 19.1-6. Ventilated Transformers—Approximate Dimensions in Inches 814EFR842AFR843A12262.91 (1598)33.75 (857)38.70 (983)29.97 (761)22.45 (570)23.51 (597)33.97 (863)17.40 (442)24.38 (619)FR844AFR939FR94022244.92 (1141)28.00 (711.2)36.77 (934)26.27 (667)21.86 (555.2)24.86 (631.4)27.12 (689)17.75 (450.8)21.13 (536.7)FR942FR943FR944FR945222243.00 (1092.2)50.92 (1293.4)60.00 (1524.0)60.00 (1524.0)30.50 (774.7)34.49 (876)38.00 (965.2)45.00 (1143)24.00 (609.6)31.48 (800)33.45 (849.6)36.00 (914.4)EATON www.eaton.com
Dry-Type Distribution TransformersGeneral PurposeGeneral Purpose Ventilated Transformers With Integral BreakersDesign Guide DG009001ENEffective February 202019.1-11OverviewEaton’s Breaker Integrated Transformers(BITs) provide a simple, cost-effectiveapproach to reducing arc flash risk andincreasing flexibility for mountingsecondary panels. By integrating thesecondary molded case circuit breakerinto the low-voltage dry-type distributiontransformer package, arc flash incidentenergy values for secondary panels canbe greatly reduced (usually to lessthan 8 cal/cm2). Additionally, with thetransformer secondary protectionintegrated into the transformer,placement of the secondary panelis not required to be within 10 feet tomeet NEC requirements. This allowstotal flexibility in the placement of thesecondary panels to be closer to loads,reducing individual branch conductorlengths / voltage drop, or placement inany available location when existingspace is limited.Breaker IntegratedTransformers (BITs)can be supplied with integrated primarybreakers, secondary breakers or both,giving you the ultimate flexibility to meetthe specific disconnect and overcurrentprotection needs of your application.Transformers arrive fully factory assembled and factory tested to help you reduceinstallation time and expense.They areavailable in a wide variety of differentventilated transformer options such asgeneral
Jan 01, 2016 · The transformer core is constructed using high-grade, non-aging, silicon steel with high magnetic permeability, and low hysteresis and eddy current losses. Maximum magnetic flux densities are substantially below the saturation point. The transformer core volume allows for efficient transformer
