power distribution - Siemens

7TRANSFORMERSTransformersDry Type Distribution 600 Volt ClassK-Factor Rated For Non-Linear LoadsFurnish and install K-Factor rated dry typetransformers of the two winding type,self-cooled, with 60Hz ratings as indicatedon the electrical plans. Unless specifiedotherwise, provide standard NEMAtaps, standard impedance, and standardsound levels. Transformers shall beSiemens or approved equal.Transformers shall be designed, manufactured,and tested in accordance withANSI, NEMA and IEEE Standards andshall be UL Listed. The self-coded kVArating shall be suitable for 30°C average,40°C maximum ambient temperature.Non-Linear rated transformers shall besuitable for nonsinusoidal loads and harmonicdistortion as indicated in IEEEC57.110, and shall be designed with thefollowing K-Factor rating (choose one):K4 for 50% Non-Linear loadK13 for 100% Non-Linear loadK20 for 150% Non-Linear loadK30 for 200% Non-Linear loadNon-Linear rated transformers shall beUL Listed and shall bear the UL markingon the nameplate along with the specifiedK-Factor rating. Non-Linear ratedtransformers shall include the followingdesign features:a) Core designed to withstand voltagedistortion and high frequencyharmonic currents. Magnetic fluxdensity designed to reduce eddycurrents and prevent saturation oroverheating of the core.b) Primary and secondary coilsdesigned to minimize stray losses,skin effect losses, and excessiveheating from harmonic currents.Coils shall not exceed the specifiedwinding temperature rise, the correspondinghot spot temperaturerating, or the 220°C insulation ratingwhile carrying the specifiedNon-Linear load.c) Neutral bus sized for 200% ofrated current to withstand circulatingcurrents and triplen harmonics.d) An Electrostatic Shield betweenthe primary and secondary windingand grounded to a common pointwithin the transformer enclosure.When properly grounded, theshield shall provide noise isolationand attenuate common mode andtransverse mode noise transientsunder normal loading conditions.e) The design and materials usedshall enable the transformers tocomply with NEMA TP1 efficiencystandards.Transformers rated 15 kVA and largershall be a ventilated dry type with a ULListed 220°C insulation system. Unitsshall be designed to operate with arated maximum temperature rise of150°C (Provide optional 115°C or 80°Crise when specified).Construction shall consist of aluminumwindings and arranged to brace coil layersand provide maximum ventilation.(Provide optional copper windings whenspecified). Cores shall be constructed ofnon-aging electrical grade steel withhigh magnetic permeability and low losscharacteristics.Core laminations shall be tightly assembled.The complete core and coilassembly shall be impregnated withnon-hydroscopic thermo-setting varnishto provide a high dielectric, moistureresistant,and flame retardant seal.SpecificationsCore and coil assemblies shall be constructedto provide short circuit withstand capability as defined by ANSI andNEMA standards. The complete assemblyshall be installed on vibration dampeningpads to reduce noise and securelybolted to the enclosure base. A flexiblegrounding conductor shall be installedbetween the core and coil assemblyand the transformer enclosure.Enclosures shall be ventilated, heavygauge steel construction finished withlight gray paint. Front and rear coversshall be removable to provide access tothe terminal compartment. Terminalsshall be fully sized to carry the transformerfull load current and shall bearranged to accept required UL-Listedcable connectors. Units installed outdoorsshall have a UL-Listed type 3Routdoor enclosure, or shall be UL Listedwith optional weathershields installed.Standard voltage ratings shall be suppliedwith NEMA standard taps for thehigh voltage windings.Unless specified otherwise, averagesound levels (150°C rise) shall meet thefollowing ANSI/ NEMA standards:0 to 9 kVA 40 dB10 to 50 kVA 45 dB51 to 150 kVA 50 dB151 to 300 kVA 55 dB301 to 500 kVA 60 dB501 to 700 kVA 62 dB701 to 1000 kVA 64 dBEach transformer shall have a securelyattached nameplate providing completeelectrical ratings, wiring diagram, tapconnections, and catalog number, asapplicable.7-4Siemens Power Distribution & Control, SPEEDFAX 2007-2008 Product Catalog