Cast Coil Dry Type Distribution Transformers

Cast Coil Dry TypeDistribution TransformersDescriptive Bulletin 47-950 Revised 04/05The Musselman Group, Roanoke, VA112.5 kVA Through 15,000 kVA2300V Through 46 kV Primary Voltage120V Through 15 kV Secondary VoltageABB Inc.State Rt. 42, P.O. Box 38Bland, VA 24315(276) 688-3325 Fax: (276) 688-4588www.abb.com/transformers

Quality Products.Built With PrideABB is the global leader in power and automation technologies, partnering with utilityand industrial customers to improve performance while reducing environmental impact.We are a full line transformer supplier representing an international community of 58ABB transformer factories in 30 countries.Our people make certain that our world renowned quality is exemplified by everyproduct that bears the ABB name. An experienced and dedicated work force ensures thequality of our work and your satisfaction with our products. We strive for operationalexcellence, lowest manufacturing cost, and short cycle times.ABB’s mission is to be the leader in delivering quality products and services forgeneration, transmission and distribution, industrial processes, mass transit, andenvironmental control that meet the needs and requirements of our customers andcontribute to their success. To ensure customer satisfaction, ABB provides value-added,integrated solutions that are driven by superior technology and performance.ABB employees are committed to leadership in applying the company’s uniquecombination of experience and global resources to meet societal goals for sustainablegrowth and clean energy.1

Cast Coil transformers are designed to meet the demands of higheroperating voltage systems and extreme environments where efficiency anddependability are crucial.ABB’s Cast Coil transformers provide the utmostspace saving design along with ultimate reliability andefficiency. No other transformer comes close to theperformance of Cast Coil for severe operatingconditions.Cast Coil transformers are non-flammable andmoisture proof. They feature a solid insulationsystem which is partial discharge free. The coildesign has minimal exposed surfaces that aresmooth and predominantly vertical. This featurevirtually eliminates particulate matter accumulationand minimizes maintenance.Ultimate reliability, quick installations, lowoperating costs, and minimal maintenance,combined with superior dielectric capabilities, makeABB Cast Coil transformers the transformer ofchoice for extreme applications.Computer controlled epoxy mixing for exacting consistency.Product Scope: 112.5 kVA-15,000 kVA Primary Voltages: 2300V through 46 kV Primary BIL: Up to 250 kV Secondary Voltages: 120V through 15 kV Secondary BIL: Up to 95 kVABB’s Cast Coil transformers are designed for the most demandingTemperature Rise: 80/115 Ccustomer requirements. The high voltage windings, which are the mostConstruction features: HV Coils Vacuum Cast in Epoxy in a MetalMold LV Coils 2400V and Less HermeticallySealed in Epoxy LV Coils Greater Than 2400V Cast UnderVacuum in a MoldBenefits/Advantages: Ultimate Impulse Withstand Minimal Maintenance No Liquids to Leak No Danger of Fire or Explosion UL Listed, ISO 9001 Registered Partial Discharge Free (Less than20PC @ 120% operating voltage) 185 C Insulation Class Moisture and Chemical Resistant Available With Indoor or Outdoor EnclosuresThe Cast Coil Processsensitive and vulnerable part of any transformer, are cast under vacuum andlocked in place by a heavy epoxy build. This concrete-like block protectsthe windings from distortion during power surges, the crushing forces ofshort circuits, and provides unequalled integrity required for operatingvoltages up to 46 kV and 250 kV BIL. The electrical integrity of thisdesign is complemented by its flexible construction geometry. Cast Coilunits utilize round or cruciform core and coil designs for specifically harshloads with brutal short circuit demands.Typical Applications Offshore Drilling Platforms Windmills Traction Substations Automotive Assembly Wastewater Treatment2

Core and Coil ConstructionCore ConstructionABB Cast Coil transformers utilize astep-lap mitered core construction toensure optimum performance andminimal sound levels. The mitered corejoints allow efficient flux transfer alongnatural grain lines between the core legsand yoke. The step-lap constructionfurther enhances the efficiency of thejoint by reducing joint fringing, whichreduces core losses and exciting current.Step-lap mitered core joints are utilized forefficiency and noise reduction.High voltage disk windingThe core is manufactured from highpermeability, cold rolled, grain orientedsilicon steel. The steel is precision cut toassure that it will be smooth andburr-free.The core is designed to provide the lowestpossible losses from the effects of magnetichysteresis and eddy currents. All possiblesteps are taken to prevent local circulatingcurrents and to avoid built-in bendingstresses.Low voltage coils hermetically sealed and low voltageinjection cast with cooling ductsVacuum cast high voltage withlow voltage coilCoil ConstructionABB Cast Coil transformers utilize theelectrical and mechanical strength ofepoxy to provide the highest levels ofperformance and environmentalprotection.Low Voltage WindingsLow voltage windings are hermeticallysealed in epoxy using one of two processes.The windings can also be designed withair ducts for improved cooling performance.The first method used to seal low voltagewindings is the pre-impregnated insulationprocess. This process consists of windingthe sheet conductor(s) in parallel with anepoxy pre-impregnated sheet ofinsulation. After the winding process iscompleted the coil is baked to dry themoisture from the winding and to curethe epoxy pre-impregnated insulation.The curing process binds the coiltogether to form a solid winding block.The ends of the coil are then sealed withepoxy for added protection.The second process is to cast the lowvoltage winding in a mold. Windingswith operating voltage less than 600volts are cast utilizing a pressureinjection process. Windings withoperating voltages greater than 600 voltsare processed using the same techniquesemployed for the high voltage windings.High Voltage WindingsABB’s high voltage windings are typicallywound using rectangular magnet wire orfoil strip depending on the currentcapacity and voltage rating of thewinding. Winding construction may belayer, disk or pancake construction.Transient analysis tests have beenperformed to verify the electrical stressdistribution through the windings.Primary windings are cast in epoxy, in amold, under vacuum using a computercontrolled mixing and vacuum castingprocess that insures the absence of voids.The epoxy used in the vacuum castingprocess is a mineral filled epoxy that isapproved by UL. The mineral filledepoxy has been proven to enhance pureepoxy to increase its thermal conductivity,mechanical strength, arc resistance, andadhesion to the conductor; and changeits coefficient of thermal expansion to becloser to that of the conductor material.The windings are also fiberglassreinforced to provide additionalmechanical strength. Each winding ispartial discharge tested using inducedvoltage after it is completed to insurethat it is void free.3

Indoor/Outdoor ApplicationNEMA1Indoor EnclosureABB Cast Coil transformers areutilized in some of the harshest indoorand outdoor environments imaginable.While core and coil technologies havebeen enhanced to combat caustic andhumid environments, transformers stillrequire the protection of a properlydesigned enclosure.An enclosure which flexes or bendsunder high wind loading cancompromise electrical clearances fromthe transformer to the enclosure,which can lead to transformer failuresas well as electrical safety hazards. Anenclosure that allows excess water entryinto the enclosure also poses unduerisk. ABB designs have been tested forextreme weather requirements and themechanical stresses associated withseismic criteria. ABB’s enclosuredesigns have been used along coastalareas and frigid northern slopes wherehigh winds and driving rain are common.Outdoor EnclosureABB enclosures are custom fabricatedusing heavy gauge sheet steel asstandard; aluminum and stainless arealso available.Electrostatically deposited dry powderpaint, baked onto a phosphatedsurface, provides added protectionagainst harsh outdoor or indoorenvironments.A variety of options ranging fromNEMA 2 drip-proof roofs to filters,screens, hinged panels, andspecial hardware can be added.Modifications can be made to extendthe enclosure, add bottom plates, addend sheets, and special cut-outs forspecific applications.4Custom enclosures with specialpaint colors are available.ABB’s dry powder state-of-theart paint system keepsenclosures looking new for years.

Forced Air Cooling Increases kVA CapacityProvisions for future fancooling (FFA)When specified, transformers, can besupplied with provisions for futureforced air cooling. This optionincludes bus work rated for increasedcurrent capacity and provisions forfuture installation of fans and fancontrol equipment.Forced air cooling (AA/FA)When specified, transformers, can besupplied with forced air cooling.Forced air cooling equipment includesfans, control wiring, thermal sensors,and a three phase electronic temperaturemonitor. The temperature sensors arelocated in the low voltage windingsand are factory connected to the threephase winding temperature monitorwhich controls the forced air coolingautomatically.The three phase electronic temperaturemonitor tracks the transformer temperaturewith automatic displays and functions.Winding Temperature Indicator providedwith isolation barrier.Typical forced air cooling increases the rated capacity of ABB Cast Coil transformers 33 1/3% onunits up to 5000 kVA and 25% for units 5001 kVA and larger.Electronic TemperatureMonitor (ETM)The ETM combines temperatureindication and fan control functionsfor the transformer and acceptsinput from three thermal sensors.Features: Digital temperature display Hottest winding temperature isautomatically displayed Temperature of any singlewinding can be displayed Maximum temperature can berecalled even if the supplypower has been interrupted Fan, alarm, and trip functionsare controlled by the hottestwinding temperature DPDT contacts are providedfor fan, alarm, and trip functions Contacts are dry Alarm relay is fail-safe Fans can be manually operated Includes internal sonic alarm,which can be temporarily silencedwithout canceling the alarm circuit Isolation box to separate gaugefrom energized components Alarm reset can be automaticor manual with auto conditionstart-up State-of-the-art solid stateconstruction UL component recognized Non-magnetic Type Ethermocouple standard Easy retrofit with existing panels Open thermocouple circuits aredetected and indicated, but donot affect instrument operation Accepts 115 or 230 VAC supplypower Form C relays.Optional Features Fan exerciser (programmable)will energize fans once per week Remote communication availablethrough RS-232 port.5