GENERAL Cooper Power Systems Primary orSecondary Open SubstationTransformers are designed to meetexact customer specifications.Flexibility in design, combined withthe highest quality manufacturingprocesses and equipment, enableCooper Power Systems to provide aproduct optimized to the customer’srequirements. All units meet applicableANSI, NEMA, IEEE Standards andNEC® and CEA specifications.

Open substation transformers areavailable with cover or sidewall-mounted bushings.

Substation transformers are made witha wide range of core steels and wind-ing conductors to meet total owningcost or material requirements. Flexiblecore and tank construction enablesyour dimensional requirements to bemet.

Cooper Power Systems transformersare available with standard electricalgrade mineral insulating oil or otherdielectric coolants manufactured byCooper Power Systems.

Open substation transformers intendedfor indoor use are filled with R-Temp®

fluid, a less-flammable, high molecularweight hydrocarbon with a flawlessfire safety record. Electrical codesrecognize the advantages of using R-Temp fluid both indoors and out-doors for fire sensitive applications.R-Temp fluid-filled units meet OSHAand Section 450-23,1996 NECrequirements. Transformers intendedfor outdoor applications may be filledwith R-Temp fluid or normally formu-lated hydro-refined mineral oil.

Substation Transformers

Primary or Secondary Open

Electrical Apparatus

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1March 1998 • Supersedes 11/94Printed in U.S.A.

Figure 1. Secondary open substation transformer equipped with cover mounted bushings.

2

Primary or Secondary Open

Figure 2.Secondary open substation transformer with standard features and optional accessories.

DE-ENERGIZEDTAP CHANGERTap changer isexternally operable.

DRAIN/FILTERING VALVEThe combination drain andfiltering valve contains afluid sampling device.

NAMEPLATELaser-scribedanodized aluminum.

FILLING/FILTER PRESS CONNECTIONOne-inch upper filling and filter pressconnection.

PRESSURE RELIEF DEVICEActivated by excessive tankpressure.

DISTRIBUTIONCLASSARRESTER

TANK LIFTING LUGSLift hooks welded to thetank at each corner forlifting.

GROUND PADSNon-corrosive, stainlesssteel ground pads onthe front and rear.

LIQUID LEVEL GAUGEMonitors oil level.Available with alarm contacts.

BASESuitable for skidding,rolling and jacking.

LIQUID TEMPERATURE GAUGEFor easy monitoring of oiltemperature. Available with multiple alarm contacts.

PRESSURE/VACUUMGAUGEAvailable with bleeder valve.

STANDARD FEATURES■ De-energized tap changer,

externally operable■ Extra-heavy, welded-in-place

lifting lugs and jack pads■ Cover-mounted high-voltage

porcelain bushings■ Cover- or sidewall-mounted low-

voltage porcelain bushings■ Tank bases designed to allow

skidding or rolling in any direction■ One-inch upper filling plug with

filter press connection■ One-inch combination drain/filtering

valve with sampling device■ Available in ANSI #61 Light Gray or

ANSI #70 Sky Gray■ Tank interior is painted light gray,

improving visibility for field inspec-tion and servicing

■ Pressure test connection■ Dial-type thermometer■ Dial-type liquid level gauge■ Pressure vacuum gauge■ Stainless steel grounding pads■ Laser-scribed anodized aluminum

nameplate■ Cooling radiators are welded

directly to the tank■ Standard grade mineral insulating

oil (for outdoor applications)■ Pressure relief device

OPTIONAL ACCESSORIES■ Pressure vacuum bleeder valve■ Cover-mounted pressure relief

device (for oil-cooled units; standardwith R-Temp units)

■ Detachable, bolt-on radiators withvalves

■ Monitoring devices■ Dial-type thermometer with

alarm contacts (standard with FA Fan Package)

■ Liquid level gauge with alarm contacts

■ Pressure/vacuum gauge with alarm contacts

■ Cover mounted pressure relief device with alarm contacts

■ Rapid pressure rise relay■ Optional seal-in panel

■ Winding temperature indicator withalarm contacts

■ R-Temp less-flammable fluid andother environmentally desirablefluid options

■ Forced air fan control package■ Package includes fans, NEMA

3R control box, fan controls, dial-type thermometer with alarm contacts

■ Cover-mounted porcelain bushings■ Nitrogen blanket with purge valves

(3 psi)■ Control box

PROTECTION OPTIONS■ Distribution, intermediate or station

class surge arresters■ Kyle® Vacuum Fault Interrupter

(VFI)

3

4

ELECTRICAL DATA

TABLE 1Three-phase, Single Temperature kVARatings

TABLE 6Insulation Test Levels

Three-phase kVASelf-cooled and forced-air cooled

with 65° C temperature rise

65° C Rise 65° C RiseOA OA/FA

500 575750 862

1000 +15% 11501500 17252000 2300

2500 31253750 46875000 +25% 62507500 9375

10000 12500

kV BIL Low Voltage Class < 2400 V ≥ 2400

45-150 5.752

6.503

200 7.25 7.00250 7.75 7.50

Self-cooled, NEMA AverageTwo Winding

dB, OA dB, FAkVA Rating

500 56 67501-700 57 67701-1000 58 671001-1500 60 671501-2000 61 672001-2500 62 672501-3000 63 673001-4000 64 674001-5000 65 675001-6000 66 686001-7500 67 70

7501-10000 68 71

Three-phase kVASelf-cooled and forced-air cooled with dual rated 55/65° C temperature rise

55° C Rise 65° C Rise 55° C Rise 65° C RiseOA 0A OA/FA OA/FA

500 560 575 644750 840 862 965

1000 1120 1150 12881500 1680 1725 19322000

+12%2240 2300 2576

2500 2800 3125 35003750 4200 4687 52505000 5600 6750 70007500 8400 9375 10500

10000 11200 12500 14000

kV Class Induced Test kV BIL Applied Test180 or 400 Hz-7200 Cycle Distribution Power 60 Hz (kV)

1.2 30 45 102.5 45 60 155.0 60 75 198.7 TWICE 75 95 26

15.0 RATED 95 110 3425.0 (Grd Y Only) VOLTAGE 125 150 4025.0 150 150 5034.5 (Grd Y Only) 125 150 5034.5 150 200 7046.0 200 250 95

TABLE 5Three-phase, Dual Temperature kVA Ratings

1 The standard tolerance is ± 7.5%.2 Option for 6.75% is available.3 Option for 5.50% is available.

Standard Optional

Unit Rating 65° C 55/65° CAmbient Temperature Max. 40° C 40° CAmbient Temperature 24 Hour Av. 30° C 30° CTemperature Rise Winding1 65° C 55° CTemperature Rise Hotspot 80° C 65° C

TABLE 7Temperature Rise Ratings 0 - 3300 feet (0-1000 meters)

1 Average Rise by resistance. Refer to NEMA Standards TRI; ANSI Standard C57.12.00.Note: Derate kVA by 0.4% for each 100 M (330 ft.) that the altitude is above 1000 M (3300 ft.).

TABLE 4Audible Sound Levels

TABLE 3Percent Impedance Voltage1

Single-phase kVA Self Cooled

55/65° or 65° C RiseOA

500667883

125016672500

TABLE 2Single-phase, kVA Ratings1

1 Larger kVA’s available; contact Cooper Power Systems.

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5

CONSTRUCTIONCoreThe three-legged, step-lap miteredcore construction is manufacturedusing a high-quality cutting machine.For maximum efficiency, cores areprecisely stacked, virtually eliminatinggaps in the corner joints.

Five-legged wound core or shell-typetriplex designs are used for wye-wyeconnected transformers, and otherspecial transformer designs.

Cores are manufactured with preci-sion cut, burr-free, grain-oriented sili-con steel. Many grades of core steelare available for optimizing core lossefficiency.

CoilsSubstation transformers feature a rectangular coil configuration withwire-wound, high-voltage primariesand sheet-wound secondaries. Thedesign minimizes axial stress devel-oped by short circuits and providesfor magnetic balancing of tap connections.

Coils are wound using the highestquality winding machines providingexacting tension control and conduc-tor placement for superior short-circuitstrength and maximum efficiency.

Extra mechanical strength is providedby diamond pattern, epoxy coatedpaper insulation used throughout thecoil, with additional epoxy at heavystress points. The diamond patterndistribution of the epoxy and carefullyarranged ducts provide a network ofpassages through which cooling fluidcan freely circulate.

Coil assemblies are heat-cured undercalculated hydraulic pressure toensure performance against short-circuit forces.

Core and Coil AssembliesSubstation transformer core and coilassemblies are braced with heavysteel end plates to prevent the rectan-gular coil from distorting under faultconditions. Plates are clamped inplace using presses, and welded orbolted to form a solid core and coilassembly.

TanksTransformer tanks are designed forhigh strength, and ease of handling,installation, and maintenance. Tanksare welded using precision-cut, hot-rolled, pickled and oiled steel. Theyare sealed to protect the insulatingfluid and other internal components.

Transformer tanks are pressure-testedto withstand 7 psig without permanentdistortion and 15 psig without rupture.

Tank FinishAn advanced multi-stage finishingprocess exceeds ANSI C57.12.28standards. The eight-state pretreatmentprocess assures coating adhesionand retards corrosion. It converts tanksurfaces to a nonmetallic, water insoluble iron phosphate coating.

The three-step, epoxy primer (E-coat)provides a barrier against moisture, saltand corrosives. The electrostatically-applied, oven-cured polyester powercoat (P-coat) enhances resistance toabrasion and impact. A urethane finalcoat seals and adds ultraviolet protection.

Vacuum ProcessingTransformers are dried and filled withfiltered insulating fluid under vacuum,while secondary windings are ener-gized. Coils are heated to drive outmoisture, ensuring maximum penetra-tion of fluid into the coil insulation system. Special attention to moistureremoval is the major reason forCooper’s track record of superior reliability and service life.

Cooling SystemOil-Air (OA) cooling is provided withtransformers rated 500 kVA. A choiceof OA-FFA (Future Forced Air) or OA-FA (Forced Air) cooling is providedwith units rated 750 kVA and above.

Insulating FluidCooper Power Systems transformersare available with standard electricalgrade mineral insulating oil or otherdielectric coolants manufactured byCooper Power Systems. The highlyrefined oil is tested and degassed toassure a chemically inert product withminimal acid ions. Special additivesminimize oxygen absorption andinhibit oxidation. To ensure highdielectric strength, the oil is retestedfor dryness and dielectric strength,refiltered, heated, dried, and storedunder vacuum before being added tothe completed transformer. R-Tempfluid, manufactured by Cooper PowerSystems under strict quality control for

optimum transformer cooling charac-teristics, provides higher dielectricstrength than mineral oil. The specialformulation is less flammable asdefined by the National Electric SafetyCode, as well as non-toxic andbiodegradable. Envirotemp® FR3 fluid,the fluid used in Envirotran® trans-formers is a fire resistant, naturalester-based fluid. Envirotemp FR3 fluidoffers the advantage of a seed oil-baseddielectric coolant with food gradeadditives, in addition to increased firesafety when compared to mineral oil.R-Temp and Envirotemp FR3 fluidcan be used in a open substationtransformer next to buildings or insidebuildings with suitable containmentprovisions.

SUBSTATION VFITRANSFORMERThe VFI transformer combines a con-ventional Cooper Power Systems dis-tribution transformer with the provenKyle Vacuum Fault Interrupter (VFI).This combination provides both volt-age transformation and transformerovercurrent protection in one spacesaving, money saving package.

The substation VFI transformer withtransformer protection protects thetransformer and provides proper coor-dination with upstream protectivedevices. When a transformer fault oroverload condition occurs, the VFIbreaker trips and isolates the trans-former.

The three-phase VFI breaker hasindependent single-phase initiation,but is three-phase mechanicallygang-tripped. A trip signal on anyphase will open all three phases. Thisfeature eliminates single-phasing ofthree-phase loads. It also enables theVFI breaker to be used as a three-phase loadbreak switch. Because theVFI breaker is resettable, restoringthree-phase service is faster and eas-ier.

R-TRAN™ FM APPROVEDTRANSFORMERCooper Power Systems’ R-TranTransformer is FM Approved forindoor locations. Factory MutualResearch Corporation’s approval ofthe R-Tran transformer line makes iteasy to comply and verify compliancewith the 1996 National ElectricalCode (NEC®) section 450-23, Less-Flammable Liquid-Filled TransformerRequirements for both indoor andoutdoor locations.

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FM Approved R-Tran transformersoffer the user the benefit of a trans-former that can be easily specified tocomply with NEC, and makes FMSafety Data Sheet compliance simpler,while also providing maximum safetyand flexibility for both indoor and out-door installations. Because the “FMApproved” logo is readily visible onthe transformer and its nameplate, NECcompliance is now easily verifiable bythe inspector.

Open substation R-Tran FMApproved transformers from CooperPower Systems are manufacturedunder strict compliance with FMRCStandard 3990, and are filled with FMApproved R-Temp fire-resistantdielectric coolant.

QUALITY CONTROL■ All transformers are subjected to

Routine and Design PerformanceTests per the requirements of ANSIC57.12.00

■ Each transformer must pass thefollowing tests:■ Resistance measurements of all

windings at the rated voltage connection of each unit, and at the tap extremes.

■ Ratio tests at the rated voltage connection and at all tap connections.

■ Polarity and phase-relation testsat the rated voltage connections.

■ No load losses at rated voltage.■ Exciting current at rated voltage.■ Impedance and load loss at

rated current on the rated voltage connection of each unit.

■ Temperature rise tests■ Performed in accordance with

ANSI Standards.■ Performed on one unit of a

given rating when test recordson an essentially duplicate unit are not available.

■ Applied potential test■ Induced potential test■ Routine impulse test

Primary or Secondary Open

6 Printed on Recycled Paper

© 1998 Cooper Power Systems, Inc.R-Temp®, Envirotemp®, Envirotran® and Kyle® are registered trademarks ofCooper Industries, Inc.R-Tran™ is a trademark of Cooper Industries, Inc.National Electric Code® and NEC® are registered trademarks of the NationalFire Protection Association.UL® is a registered trademark of Underwriter’s Laboratories, Inc.

MI3/98

P.O. Box 1640Waukesha, WI 53187www.cooperpower.com