Amorphous Core Distribution Transformers: Challenges,
Opportunity and Loss Capitalization for Power Applications in India
GAYATRI AGNIHOTRI, SAVITA NEMA, R. K. NEMADepartment of Electrical
Engineering Maulana Azad National Institute of Technology, Bhopal
(M.P.) INDIA [email protected], [email protected],
[email protected],
Abstract:-Distributiontransformerisaninternallinkbetweenthedistributionnetworkandcustomers.
Keeping in view the frequent failure of distribution transformer,
power utilities in the world are now producing
distributiontransformersonthebasisoflossevaluatingfactors.Asthecostofelectricalenergyhasbeen
rapidly rising rural electricity board has introduced amorphous
metal core transformer to overcome shortage of
electricity.Iron-basedamorphousribbonhasbeenconsideredasahighefficiencyoptionfordistribution
transformercorematerialbutonlyasmallpenetrationintothemarkethasoccurred.Thispaperreviewsthe
presentstatusofamorphousmaterialindistributiontransformersandshowsthatinmanysituationsitisthe
bestoptionwheretrueenergylossesoperatingconditionsareconsideredfully.Performanceofdistribution
transformer with CRGO and with Amorphous core including losses and
improvement in efficiency is discussed in this paper. A case study
of Amorphous core transformer of 63 KVA is presented and losses are
capitalized and the payback period over the replacement of CRGO
transformer of the same capacity is evaluated. Key-Words:-
Distribution transformers, CRGO,AMDT, Load losses, Capitalisation
of losses, efficiency 1Introduction
Recentyearshavebroughtmajorchangesinthe
globalelectricpowerindustry.Shortageof
electricityishavingcascadingeffectonindustry
productionandeconomicdevelopment,whichcan
bemetbyadditiontoexistinggenerationcapacity or by more efficient
utilization of existing capacity. Duringthisera highly efficient
transformers caught the interest of electric utilities. It has been
estimated that switchover from silicon
steeltoAmorphousmetalcorewillsaveabout200
millionkWhelectricalenergyinayear.Currently
over1,250,000amorphousmetaldistribution
transformershavebeeninstalledworldwide,
helpingelectricpowerutilitiestoimprovethe
efficiencyoftheirtransmissionanddistribution system. In India
generating capacity is 130730 MW.
Even1%reductionoflossesisequivalenttoan
additionof1300MWgenerationcapacitywhich saves 5200 crores in
capital investment.
2Sources Of Losses Outoftotalpowergenerated10%aregeneration
losses,10%arecopperlossesand20%areNon
technicallosses.Inaddition20%lossesaredueto
inefficientenduse.Henceinallthereare60% losses. One of the major
sources of T & D losses in India is transformer. These losses
can be minimized byusingenergyefficienttransformerreducingno load
losses to practically one
third.Amorphousmetalcoreisbasicallyboronmixed
materialwithnon-crystallineatomicstructure. Amorphous is having
very low specific core loss but getssaturatedat1.57tesla.Lowvalueof
magnetizingcurrentandlowcorelossesmakesit
muchmoreefficient.Howeverthecostofthe
Amorphouscorematerialishigherwhichis compensated over the payback
period on account of savings due to reduced losses. 3Amorphous Core
Transformers: Some Facts And
FiguresVariousfactsabouttheamourphouscore
transformeraretabulatedinTable1-4,whichare self explanatory. Recent
Researches in Circuits, Systems, Mechanics and Transportation
SystemsISBN: 978-1-61804-062-6 172 TABLE 1: No Load Loss Comparison
Ratings (KVA) Loss FactorNo load losses (Watts) CRGOAMDTCRGOAMDT
636.8627.4418045 1006.77 29.9226060 2007.1624.51500160
31510.0831.14580200 50011.0039.81900250 Table 2: CostComparison
(Rs) KVA RatingCRGOAMDT 25 KVA2000028000 63 KVA3800052000 100
KVA4600063000 Table 3 : Comparison Of Efficiency Rating (kVA)No
Load LossesLoad LossesEfficiency (%) CRGOAMDTCRGOAMDTCRGOAMDT
2505701804000320098.298.7 5009002506550480098.5399
63010002008000520098.5499.1 73012503659000605098.6599.2
1000150045011800765098.6899.2 Table 4: Environmental Impact of
Amorphous Metal Transformers BenifitUSAEuropeJapanChinaIndia Energy
Savings(billion kWh)40251192 Oil (million barrels)704520154
(million tons)352010123 (thousand tons)11070309022 (thousand
tons)2601607521052 Recent Researches in Circuits, Systems,
Mechanics and Transportation SystemsISBN: 978-1-61804-062-6 173
4Capitalization of Losses
Distributiontransformeristhemostwidelyused
equipmentinthepowerdistributionnetwork.Dueto
poorperformanceofthousandoftransformersload
andnoloadlossesoccurthroughoutthelifeofthe
systemcausingrevenuedegenerationyearafteryear. Toillustratethe
effect of these losses, the capitalized
costfordistributiontransformerinIndianPower System is worked out in
the present paper. Tocalculatethecapitalizedcostofnoloadlosses,
theguidelinessuggestedbyanexpertcommittee
consistingofrepresentativesfromvariousState Electricity Boards
(SEBs), Central Board of Irrigation
andPower(CBIP),IEEMAandRuralElectrification
Corporation(REC)areusedhere.Themethodand
formulaasdecideduponbytheworkingcommittee follows.
Fromtherecommendationofthecommittee,the
CapitalizedcostoftransformernoloadlossesinR /Kw is given by ( )( )
+ +=nnr rrE H A1 *1 1* ...(1) Where,
H=No.ofservicehoursperyearofthedistribution transformer r = Rate of
interest n =Life of transformer in a year
E=EnergyCost,i.e.thecostofelectricalenergyat
thebustowhichtransformeristobeconnected (Rs/KWh).
SimilarlytheCapitalizedcostof loadlossesinRs/ kW (B) may be given
in terms of the cost of no load losses (A) by defining a loss load
factor(L.S.), B =A* L.S....(2)
WiththisinterpretationofAandBthecapitalized cost of the transformer
(TOC) may be given byTOC=InitialCostofTransformer + Cost of the
No-load Losses + Cost of the Load Losses= IC + (A*Wi) + (B*Wc)
...(3) Where, IC=Initialcostoftransformerasquotedbythe manufacturer
(Rs)Wi = No load losses of the transformer Wc = Load losses of the
transformer According to REC the values described for various
parametersofequations[1-3]are:(Assumingthat transformer is not in
service for 15 days in a year due to repair and maintenance) 1.No.
of service hours: H = 350 * 24 = 8400 hrs 2.Life of transformer:n =
25 years 3.Rateofinterest:Aftertakingintoaccount
variousfactorstherateofdiscountforthe
investmentinthecapitalizationformulais decided as 12 % i.e.r = 12%
4.Loss load factor (LS): This is given in terms of the load factor
(LF) as per the recommendation of the working committee LS =0.2 LF
+ 0.8 LF2= 0.132 ...(4) AssumingenergychargesasRs2.70perunitat11 KV
terminal distribution transformer values of A and B factor can be
worked out. Fromeq.(1);Capitalizedcostofnoloadlosses A= 177,882
Rs/kW From eq. (2) & (4); Capitalized cost of load losses B=
23,480 Rs/kWFrom eq. (3) Capitalised cost of the transformer =
IC+177882*Wi+23480*Wc. .(5) 5Comparison of Capitalised Cost
TheTable1Comparesthetwotypesofthe transformer w.r.t. to no load and
load losses. For a 63 KVA transformer load losses as per the Table
is 1235 watts. Initial cost of CRGO transformer = Rs 38000/
Capitalized cost ofCRGO transformer (from eq. 3) = Rs 99016/
Initial cost ofAmorphous core transformer= Rs 48000/ Capitalized
cost of Amorphous core transformer= Rs 85002/-
ThoughtheinitialcostofAmorphouscore
transformerishighbutoveraperiodofoneyearthe
Amorphouscoretransformerisdefinitelycheaperas
itscapitalizedcostisapprox.85,000/-againstthe
capitalizedcostofRs.99,016/-forCRGOandalso saves the considerable
amount of energy. The losses of the 63 KVA Distribution Transformer
inIndianPowerSystemarecapitalizedovera period of 1 year.Generated
capacity committed to feed these losses shall include the losses in
the system and shall takeintoaccounttheplantloadfactor.Plantload
factor is assumedas 60 % and minimum losses up to
thedistributiontransformeris10%.Assuming50%
ofthedistributiontransformeroperatesunderfull
loadduringpeakhoursthecapitalizedsystemlosses
withCRGOandAmorphoustransformersare calculated, capitalized and are
tabulated in Table 5. A
comparativestudyofdesignparametersfordifferent
ratingiscarriedoutanditisfoundthatthoughthe Recent Researches in
Circuits, Systems, Mechanics and Transportation SystemsISBN:
978-1-61804-062-6 174 initialcostof63KVAtransformersisonhigherside
but when the losses are capitalized it is found to be on lower
side. 6Challenges and Opportunities
Whenswitchingfromastandardtoahigh
efficiencytransformer,oneshouldinvestigateif
thereisenoughspaceandwhetherthefoundation
cansupporttheadditionalweight.Amorphous transformers have about 50%
bigger cores. OtherfielddataindicatesthatforTotalHarmonic
Distortion level of 75% the increase in no load loss
inamorphouscoresisaround60%whereasitis 300% in transformers with
silicon-iron cores. Replacingalldistributiontransformersbyenergy
efficienttypescouldsave200TWhayear, equivalent to 130 million
tonnes of CO2 emissions (table1.4).Anadvantagelargeenoughtojustify
the effort.Introduction to Amorphous core can brought about
adramaticchangeintheperformanceof
distributiontransformer,whichreducestheNo-loadlossto70%and60%lowerexcitingcurrent
andasmallertemperatureriseascomparedto CRGO steel core
transformer[11]. 7CONCLUSION High-efficiencytransformersareamature
technologywiththeireconomicandenvironmental
benefitsclearlydemonstrated.AlthoughAmorphous
metaltransformersareoftenmoreexpensivethan
siliconsteelunitstheycanbemorecosteffectivein many electric power
systems. Where energy costs are sufficiently high, amorphous metal
transformers make economic as well as environmental senses.
References: [1]REC (Rural electrification corporation) 70 / 1994
specification for distribution transformers
[2]IS2026(P-ItoIV)specificationforpower
transformersupto100KVAJ&PTransformers handbook.
[3]LossesindistributiontransformersbyS.V.Deo, R.B. Joshi &
S.P.Nophade MSEB Bombay. [4]Design of Transformers by Dimkov.
[5]Energy Scene in India by G. Srivamamurthy.
[6]LossesindistributiontransformersbyMr.R.S. Shah. Emco
Transformers Ltd. [7]PerformanceofDistributionTransformersby V.N.
Prahlad Indo-Tech Transformers Ltd.
[8]ElectricalEnergyEfficiency,Copper Development Ass. p. 116, 1997.
[9]A.J.Moses,J.Leicht,IEEETrans.Magn.37, 2737 (2001). [10]
L.LowdermilkandA.C.Lee,FiveYears OperatingExperienceWithAmorphous
Transformers, Hard And Soft Magnetic Material ASM(1998) [11]
Electricitydistributionlosses-aconsultation
document.Technicalreport,OffceofGasand Electricity Markets, 2003.
[12]InternationalEnergyOutlook.Energy Information Administration,
2003. [13]World Energy Investment Outlook. International Energy
Agency, 2003 Recent Researches in Circuits, Systems, Mechanics and
Transportation SystemsISBN: 978-1-61804-062-6 175 Table 5
S.noParametersCRGOAMDT 1.No. of distribution
transformers15,00,00015,00,000 2.No load loss=No. of transformer*No
load losses/transformer/106 270MW67.5MW 3.Cost of no load losses
per year in Rs408.24 Crores102.06 Crores 4.Load
losses1852.5MW1852.5MW 5.Cost ofload losses per year in Rs2800.9
Crores2800.9 Crores 6.Generated capacityrequired to feed no load
losses495 MW123.75 MW 7.Generated capacityrequired to feed load
losses1698 MW1698 MW 8.Total generation capacity required to feed
losses495+1698= 2193 MW 1821.75 MW 9.Investment cost for generation
and T & D to feed losses(Rs 5crores/MW) 10965 Crores9108.75
Crores 10.Investment cost of distribution transformer in Rs5700
Crores7200 Crores 11.Total capital Investment in Rs16665
Crores16308.75 Crores Recent Researches in Circuits, Systems,
Mechanics and Transportation SystemsISBN: 978-1-61804-062-6 176
