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1 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Frequent Questions & Answers for DuPont TM ReliatraN Global Energy Solutions Version1 dated June,2003 Slide 2 2 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n Contents n What is ReliatraN page 5 ~ 6 n ReliatraN Criteria page 7 n What is NOMEX? page 8 ~ 15 n What are the major advantages of page 16 ReliatraN Brand Transformers ? ReliatraN Brand Transformers ? n What are the benefits to the users of page 17 ReliatraN Brand Transformers ? ReliatraN Brand Transformers ? n How does DuPont maintain the high quality page 18 ~ 20 and reliability of ReliatraN transformers? and reliability of ReliatraN transformers? n How does ReliatraN perform under moisture? page 21 ~ 27 Slide 3 3 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n Contents n How does ReliatraN perform under dirty condition? page 28 ~ 29 n Whats the meaning of load loss by various insulation class? page 30 ~ 33 n How is dielectric withstand of ReliatraN ? page 34 ~ 35 n How well does ReliatraN perform during overloading? page 36 ~ 37 n How well does ReliatraN withstand short circuit ? page 38 n What is the fire behavior of ReliatraN ? page 39 ~ 45 Slide 4 4 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n Contents n How is ReliatraN environmentally friendly ? page 46 ~ 48 n What does partial discharge mean to dry type transformer ? page 49 n What is VPI process ? page 50 ~ 51 n What is the maximum rating of ReliatraN transformers? page 52 n Index page 53 Slide 5 5 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n ReliatraN is poised to be the chosen brand for value-added transformer solutions that apply to various distribution transformer applications. n What is ReliatraN ? Slide 6 6 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. DuPont TM ReliatraN Brand Transformers are manufactured with UL Certified Insulation Materials, by a global network of ISO 9001 Certified Manufacturers, meeting the highest of International Standards for Quality, Design, Construction and Performance DuPont TM ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Providing Global Energy Solutions to the Electrical Industry Slide 7 7 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n DuPont TM ReliatraN Criteria n The ReliatraN standards are continuously reviewed to incorporate new experience, materials, test procedures, etc or to adapt new requirements Slide 8 8 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n The superior electrical properties of NOMEX paper and pressboard provide unique capabilities for electrical equipment, resulting in new classes and ratings. This includes: n High Level of Safety n Increased Load Capability n Reduced Size and Weight n Long Term Reliability n What is NOMEX ? Slide 9 9 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n NOMEX Electrical Insulation has been used in the most critical applications in all types of electrical equipment. Ventilated Dry Transformers Resin Cast Transformers Liquid Immersed Transformers Generators AC/DC Motors Reactors Hermetic Motors Gas Filled Transformers Slide 10 10 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions The unique capabilities of materials made from Nomex aramid polymer are a result of its superior Thermal, Chemical, Mechanical and Electrical properties The Advantages of NOMEX Slide 11 11 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n Long Term Stability up to 220C n Short term exposures up to 350C is possible n Stable properties over a wide range of temperature and humidity conditions n Will not Melt, Flow or Support Combustion below 250C, with no toxic or corrosive Off-Gases below 750C THERMAL The Advantages of NOMEX Slide 12 12 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions n No weak C-H bonds creates a strong resistance to chemical attack by acids and alkalis n Compatible with all oils, resins, varnishes, fluorocarbons, refrigerants CHEMICAL NN C C HH OO n The Advantages of NOMEX Slide 13 13 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions MECHANICAL n High tensile strength and tear resistance prevent manufacturing problems n High abrasion and cut resistance prevent production and operational failures n Good compression resistance provides a stable and rigid structure during short circuit or other mechanical stresses The Advantages of NOMEX Slide 14 14 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions ELECTRICAL n The low Dielectric Constant enables better distribution of stresses between the insulation and the cooling medium n The low Dissipation Factor, even at high temperatures, reduces dielectric loss n High Resistivity at high temperatures up to 250C in use n Excellent Dielectric Strength under 50/60Hz and under impulse conditions The Advantages of NOMEX Slide 15 15 The Advantages of Nomex Nomex is a DuPont Registered Trademark Slide 16 16 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What are the major advantages of DuPont TM ReliatraN Brand Transformers ? n These State-of-the-Art ventilated dry type transformers provide the best solution in reliable and versatile equipment Safe equipment which can be placed close to the loadSafe equipment which can be placed close to the load Flexibility in variable load situationsFlexibility in variable load situations Increased overload emergency capabilityIncreased overload emergency capability Reduced Size and Weight for better space utilizationReduced Size and Weight for better space utilization Economical solutions for the distribution of powerEconomical solutions for the distribution of power ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 17 17 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What are the benefits to the users of DuPont TM ReliatraN Brand Transformers ? n Highest Quality Standards DuPont standards for design and manufacture exceed the local and global standards to ensure high quality and reliability / long lifeDuPont standards for design and manufacture exceed the local and global standards to ensure high quality and reliability / long life n Longest Warranty DuPonts network of qualified manufacturers of ReliatraN transformers offer unprecedented five (5) years warrantyDuPonts network of qualified manufacturers of ReliatraN transformers offer unprecedented five (5) years warranty n Cost Savings Lowest total owning cost from purchase to disposal over the lifetime of the equipmentLowest total owning cost from purchase to disposal over the lifetime of the equipment ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 18 18 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How does DuPont maintain the high quality and reliability of DuPont TM ReliatraN transformers? n DuPont provides the most updated technology on design,manufacturing and testing to partners and continuously monitors and audits all aspects of production to deliver quality without any failure. n Simple processing enables OEMs to produce constant quality and reliability. All processes are visible to detect any potential defect of transformer. constant quality and reliability. All processes are visible to detect any potential defect of transformer. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 19 19 Coil Manufacturing Process Cast coil VDT Preheat resin Weigh resin Mix resin pouring Assemble mold curing Disassemble mold - - Impregnation(VPI) Impregnation(VPI) drying drying Sophisticated process/ many parameters to quality impact Simple process/ less parameters to quality impact - - - Slide 20 20 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n One of the special requirements for the transformer installed at Nuclear Power Plant is longer life installed at Nuclear Power Plant is longer life ( 40 years). ( 40 years). VDT had been used in many Nuclear Power Plants in US VDT had been used in many Nuclear Power Plants in US due to reliable long life due to reliable long life n Failure rate of VDT at field is less than half of that of other dry transformers in US. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 21 21 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How does DuPont TM ReliatraN perform under moisture ? n NOMEX itself has high resistance under high humidity. n VPI processing assure that windings are well protected against harsh environment such as moisture and dust. n Many tests and historical cases at operation sites have proved that VDTs were safe to operate without outage at high humid conditions. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 22 22 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n If a dry type transformer is energized after long storage period under high humidity,it is recommended either to wipe dirt and moisture or to energize without loading before placing a load on transformer. n We do not recommend starting or operating a transformer with free moisture on the coils as there may be surface deposits that are conductive when wet. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 23 23 Relative Volume Resistivity of Materials (ohm - cm) Nomex is a DuPont Registered Trademark 10 20 10 16 10 12 10 8 10 0 10 -6 10 -10 } } } } Insulators Semiconductors Conductors Superconductors Nomex 50C 220C { Nomex is a DuPont Registered Trademark Slide 24 24 Relative Volume Resistivity of Materials (ohm - cm) Nomex is a DuPont Registered Trademark 10 20 10 16 10 12 10 8 10 0 10 -6 10 -10 } } } } Insulators Semiconductors Conductors Superconductors Epoxy Resin 50C 100C 150C { Slide 25 25 Superior Humidity Resistance * RelativeDielectric Dissipation Volume HumidityConstant FactorResistivity (%) (60 Hz) (60 Hz)(ohm- cm) _____________________________________________________ Dry 2.5 0.006 10 16 50 2.7 0.006 10 16 95 3.2 0.011 10 14 * Properties for Nomex10 mil (0.25 mm) T-410 Nomex is a DuPont Registered Trademark Slide 26 26 Moisture resistance of VDT insulated with NOMEX A 1000KVA ventilated dry type transformer with NOMEX insulation was used in a special moisture demonstration by exciting the transformer at full voltage immediately after being in a thunderstorm. Nomex is a DuPont Registered Trademark Transformer description It is 1000KVA rated 13800 volts primary and 480Y volts secondary. The temperature rating is 150C rise at a max. ambient of 40C. The BIL rating of the high voltage is 95KV. The prior history of the transformer includes a short circuit test and impulse test following the short circuit test. The transformer was then subjected to higher impulses and subsequently flashed over at 138 KV. The partial discharge inception voltage when tested as individual coils was 1.9 times rated voltage at 400 Hertz excitation. The Demonstration The transformer was placed outdoors during an extremely severe thunderstorm. The thunderstorm lasted about one hour and 1.5 inches of rain fell. Immediately there after, the transformer was brought to the testing area and excitation was applied. The transformer withstood its full operating voltage with no sign of imminent flashover. Slide 27 27 Nomex is a DuPont Registered Trademark Conclusion The NOMEX insulated ventilated dry type transformer with VPI treatment exhibits superior moisture resistance and can be used in outdoor locations in a properly designed outdoor enclosure. The thunderstorm demonstration was performed to show the superior moisture resistance of coil construction. Moisture resistance of VDT insulated with NOMEX Case study by Southern Transformer Co. Alexander D.Kline,President Slide 28 28 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How does DuPont TM ReliatraN perform under dirty condition? n Coil structure is well constructed to separate each disk, which will not allow cumulative dust collection between disks. n Enough cooling space in LV, gap between LV/HV and HV ensure effective cooling even at harsh environment such as cement plants and mines n One ASEAN power utility has operated several VDTs for more than 15 years without any maintenance at all, though a thick layer of dust covered windings. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 29 29 Slide 30 30 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n Whats the meaning of load loss by various insulation class? n The higher insulation class makes it possible to build smaller size of coils, eventually leading to smaller transformer size. n The one of the advantages of H class dry type transformer is compactness and lower no load loss with more load loss compared with other transformers below H class. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 31 31 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n Most of transformers operate at significantly below the full rated load(average 60%) which benefits lower no load loss in terms of economic view. n Therefore, higher temperature designs more fully utilize the raw materials and optimize losses, which is the growing trend in the West. n Reliatran can be built for specific load loss, lower than class H transformer by request. standard class H transformer by request. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 32 32 0.94 Slide 33 33 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Temp. Coil Size Comparison Class (% of Class H) Class (% of Class H) Class B130 Class F115 Class H100 Class C 90 gher winding temperatures allow smaller coils and smaller magnetic cores, saving cost, space and weight. n Higher winding temperatures allow smaller coils and smaller magnetic cores, saving cost, space and weight. Slide 34 34 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How is dielectric withstand of DuPont TM ReliatraN ? n Due to lower dielectric constant of NOMEX than other insulation materials, It has better distribution of stresses throughout transformer n There is no thick layer of Epoxy resin which means No cracking on coils. One of the common problems with cast coil is cracking to cause failure. n Disk winding structure distributes the voltage stress evenly and efficiently to meet BIL requirement of all standards. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 35 35 NOMEX Brand Paper & Pressboard The Dielectric Constant of NOMEX sheet insulation is very low compared to most insulating materials. Nomex 1.5-2.5Air 1.0 Inorganics 3.0-5.0Mineral Oil 2.2 Glass 5.0-6.0Silicone 2.7 Epoxy4.0-6.0 Cellulose 4.5 The closer to the cooling medium(air), the better the distribution of stresses throughout the transformer. Nomex is a DuPont Registered Trademark Slide 36 36 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How well does DuPont TM ReliatraN perform during overloading? n Based on GB standard, the average winding rise is 125C and max. hottest temperature is 180C. n In this case there is temperature margin which is 40C differential between thermal capability of Nomex(220C) and max. hottest temperature(180C). This contributes to higher overloading capability. n For certain cases, one can put dual ratings on the name plate for flexible operation either with lower load loss or higher capacity. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 37 37 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Steady State Loading on the Basis of test temperature riseSteady State Loading on the Basis of test temperature rise (Quoted from ANSI C59.96-IEEE Guide for Loading Dry type distribution and power transformer) (Quoted from ANSI C59.96-IEEE Guide for Loading Dry type distribution and power transformer) ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Rated average winding temperature rise For each degree C below the rated temperature rise, increase rated load by 80C 115C 150C 0.57% 0.43% 0.35% If a 1000KVA is 100C average winding temperature rise, the additional rating for over loading can be calculated. (115C - 100C) x 0.43% + (150C - 115C) x 0.35% = 18.7% ===> 1000KVA x 1.187 = 1187KVA * Note: In general, ReliatraN provides about 30% additional capability for overloading based on practical design. Slide 38 38 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n How well does DuPont TM ReliatraN withstand short circuit ? n Design principles utilized for these transformers minimize axial and radial mechanical forces in case of short circuit accident. n Transformers using this design have passed short circuit tests mechanically and thermally for more than 30 years (in the US). n VPI process with varnish enhances mechanical strength of coils to prevent failure by short circuit accident. n In addition, the disk structure in HV coil can hold winding robustly. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 39 39 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What is the fire behavior of DuPont TM ReliatraN ? n Aramids do not melt (hence it will not help the fire to spread) and generate little or no smoke and emit no toxic gas. n Epoxy resin may emit some toxic gases when decomposed by fire such as SO2, hydrogen sulfides and halides [Ref.1] n Specialty tests like CENELEC HD-464 indicate that VDT had less smoke, less weight loss, quicker self extinguishment, less support to combustion than cast coil that VDT had less smoke, less weight loss, quicker self extinguishment, less support to combustion than cast coil n Nomex does not support combustion and can only be burned with difficulty - even at elevated temperature (LOI >> 21%) ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 40 40 Quoted from Development of Insulating Systems in Distribution Transformers - Improvement of Fire Resistant Characteristic by G.LE ROY and F.SANDOZ n Full size testing of distribution transformer behavior under fire has been possible thanks to the building by the French Coal Board Research Center (CERCHAR) of a fire gallery guaranteeing against all environment pollution risks nClass H VDT: only slight effects occurred after some times - pyrolysis of the superficial varnishes and metal frame paints ---. Let us note that this good behavior is a consequence of the choice of materials done on this equipment, on the basis of systematic fire test on samples(oxygen index at various temperatures, combustion gas analysis). Class B cast coil: Contrary to class H VDT, this equipment behavior was rather disappointing and even, in some way, surprising. About 3 minutes after being exposed to fire, whilest temperature reached only about 150C, the transformer went into flames. In spite of the radiating panels being switched off, combustion self supported itself until insulating matters complete destruction. n Conclusion: Especially the class H VDT, the only one having shown a completely satisfactory behavior during the full size fire test. Slide 41 41 Transformer typeVDTCast coilSiliconUgilec T Class H(Aramid)Class B Rating(KVA): mass tank/vessel (kg): 630 400250 250 Liquid --190/40 338/60 First fire occurrence (min): Fire end (min): 303 20 407011055 Total energy measured at 12 m from the fire (MJ after 40/60 min): Energy emitted by radiating panels (MJ): Transformer part in total energy (%): Combustible destruction part (%) Released carbon dioxide mass(kg): Released HC1 mass(kg): Released soot And dust mass (kg): 225/225600/640700/4900400/500 336 143 ** 336 48 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n There are no materials in VDT coils causing allergy and itch to human body n The quantity of materials requiring disposal is significantly less than with cast resin coils (> 4 times) n Compact size with lighter weight require less active parts,which contributes for energy saving and green environment. (Production of silicon steel/copper wire entails fossil fuel consumption resulting in air/water pollution.) (Production of silicon steel/copper wire entails fossil fuel consumption resulting in air/water pollution.) ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 49 49 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What does partial discharge mean to dry type transformer ? n Reliatran has a thinner layer of varnish without any possible air bubble inside and is designed to have low voltage stress far below corona inception voltage. n Cast coil transformers assume the epoxy resin fill the gaps and therefore design for epoxy dielectric, assuming no air - if any air bubbles appear, there will be high stress on the air and partial discharge will develop. It may cause insulation breakdown resulting in transformer failure. if any air bubbles appear, there will be high stress on the air and partial discharge will develop. It may cause insulation breakdown resulting in transformer failure. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 50 50 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What is VPI process ? n This is the most evolved technology to produce high quality coils with advanced equipment and material. n Impregnation is done inside tank under vacuum/pressure condition and there are no varnish drops outside tank. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 51 51 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n During curing, there is some evaporation of solventless varnish due to cross linking process between monomers and resin. The vapor is not toxic and is exhausted out by oven chimney. Varnish does not cause skin irritation or allergic reaction to people. n Excess varnish can be returned to storage the tank after impregnation process without any waste. ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 52 52 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n What is the maximum rating of DuPont TM ReliatraN transformers? n VDT transformers have been produced up to 15MVA and 35KV voltage class. Most popular range of product is up to 3000KVA. In general, Power Utilities limit electricity supply to users below 10 MVA as max. due to distribution reliability and economic reasons. In general, Power Utilities limit electricity supply to users below 10 MVA as max. due to distribution reliability and economic reasons. DuPont TM ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 53 53 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. n Index n 1.Safety Aspects of Using Aramid and Paper and Pressboard in Dry Type Transformer Dr.J.W.Rothuizen/ Switzerand Dr.J.W.Rothuizen/ Switzerand n 2.Development of Insulating Systems in Distribution Transformers - Improvement of Fire Resistant Characteristics G.LE Roy/ F.Sandoz/France G.LE Roy/ F.Sandoz/France n 3. Moisture Resistance of Nomex - Insulated Glazed Coils Alexander D.Kline/USA Alexander D.Kline/USA n 4.ANSI C59.96 - IEEE Guide for Loading Dry Type Distribution and Power Transformer n 5. CENELEC Norm HD 464 - Specialty test for Severe Environments,Thermic Impulse and Fire ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide 54 54 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co. Global Energy Solutions PAPER AND PRESSBOARD UL RECOGNIZED DuPont TM ReliatraN is a Trademark of E. I. DuPont de Nemours and Co.