TECHNICAL SPECIFICATION FOR OUTDOOR TYPE THREE PHASE,11/0.433 KV ALUMINIUM WOUND SEALED TYPE DISTRIBUTIONTRANSFORMER OF 25, 3 ! 100 KVA RATIN"1.0 SCOPE:Thisspecificationcoversoil immersednaturallycooledthreephase, 50Hz,double wound outdoor conventional Aluminium Wound distribution transformersof capacity 25, 6 ! "00 #$A, ""%0&' #$ for use on systems with nominalvolta(e of "" #$&2.0 APPLICABLE STANDARDS:)nless otherwise modified in this specification, the distribution transformers shallcomply with the latest versions of *+, specification ""%"-.6 and % or /01 ""20 and/012026 and latest amendments thereof&3.0 RATINGS:3.1 KVA RATINGS:The standard #$A ratin(s shall be 25, 6 ! "00 #$A&3.2 RATED FREQUENCY:The rated fre3uency shall be 50 Hz&4.0 TAPS:4o taps are to be provided in these transformers&5.0 PERMISSIBLE FLUX DENSITY AND OVER FLUXING:5lu6 density at rated volta(e and fre3uency shallnot e6ceed "&6- Tesla& The4o78oad current at rated volta(e and at ""2&59 rated volta(e shall not e6ceedvalues (iven below1 7*AT/4: ;+*,+4TA:+ $ector system =B""?, so as to produce a positive displacement of 0 =e(reefrom the primary to secondary vectors of the same phase& The neutral of secondarywindin(s shall be brou(ht out to a separate insulated neutral terminal& H&$&windin(s shall consist of ma6imum ' coils per limb e6cept for 25 #$A transformersfor which it shall be 2 only& All delta leads from H&T& coils as well as H&T& line leadsshould be ta@en out throu(h =&;&,& copper wires of sufficient C7sectionalarea toimpart desiredmechanical stren(th& Thecurrent densityintheseleadsshouldhowever not e6ceed 0&2 A%s3&mm& All the above leads should be ta@en out throu(hba@elite tubes&-&2 The windin( shall be so desi(ned as to produce minimum out of balance forces inthe transformers&-& The windin( shall be so desi(ned such that all the coil assemblies are of identicalvolta(e ratio and shallbe interchan(eable and repairin( of the windin( could bemade easily without special e3uipments&-&' The conductor used in the coil shall be best suitable to the e3uipment and all thepermanent current carryin( Doints in the windin( and leads shall be properly sleevedand crimped instead of Dointin( with solder of weldin(& All H$ ! 8$ coil ends shall beprovided with crimped lu(s&-&5 =;, insulation shall be used for wires of H$ ! 8$ windin(s& #raft paper in layer>s?of total thic@ness of not less than ' mils shall be used for interlayer insulation& =;,and #raft paper used shall be of uniform density and free from any forei(n particle&The end turn of each layer shall be properly and fully covered to avoid interlayerflashover&The#raft paperusedforthispurposeshall beinconformitywith/016-2%56>;aper for electrical purpose? andlatest amendment thereof& =ovetailedspacersshall beused between thesectionof H$windin(s&,orru(atedcylindermade from pre7compressed insulation board should preferably be used between 8$!H$Windin(s& Theinsulationof coilsshall bevacuumimpre(natedinoil todevelop the full electrical stren(th in the windin(s& All material used in the insulationandassemblyof thewindin(shall beinsoluble, noncatalytic andchemicallyinactive in the hot transformer oiland shallnot soften or otherwise be adverselyaffected under operatin( conditions&Alternatively in place of vacuum impre(nation, the core and coil assembly shall befully dried out in EAir =ryin( a? Twoearthin(terminals>studandboltsshouldbeproperly(alvanisedandconform to latest version of /01 "6 and /01 "6.?&>b? Two liftin( lu(s to lift ,ore assembly&>c? Twoliftin(lu(stolift completetransformer >not tobeprovidedonthetan@cover?>d? *atin( and terminal mar@in( plates&>e? f? ;air of arcin( horns on each H$ bushin(&>(? Air *elease ;lu( H " 4o&>h? =rain valve H 20 mm for all transformers >/t shall be covered with metallic coverby spot weldin(? H " 4o&>i? ,onservator with drain plu( and a fillin( hole with cap&>D? Thermometer poc@et to be suitably plu((ed with a threaded cap&>@? 0ilica (el breather of approved desi(n ! should contain min& 50 (m& silica (el&>l? *adiator details shall be (iven as per drawin( and to be provided on 8$ side oftan@&>m? The inside diameter of the pipe connectin( conservator to the main tan@ shallbe within 20 to 50 mm and it should proDect into the conservator in such a waythat its end is appro6imately 20 mm above the bottom of the conservator&11.0 RATING AND TERMINAL MARKING PLATE%S&:11.1 RATING PLATE:+achtransformer shall beprovidedwithanondetachableratin(andterminalmar@in(plate>s? of weather proof material, fittedinvisibleposition, mentionin(completeinformationas(ivenin,lauseH"5&"and"5&2of latest versionof/012026 >;art7/?& /n place of 0erial4umber of Transformer, )4/I)+ 4o& shallbepunched on ratin( plate& )ni3ue number has been allotted indicatin( the name ofthe firm, capacity, specification and serial number of the transformers& 4o78oad%8oad losses must also be en(raved on the dia(ram plate& The entries on theratin( plate shallbe invariably mar@ed >by etchin(, en(ravin( or stampin(?& ;lateshould be firmly riveted with tan@ so that it may not be detached afterwards&""&2 )ni3ue number has to be punched on the top cover and sidewall of transformer invisible condition& J=$$48 ;*"-2"? or anyamendments thereof&14.0 INSULATION LEVEL:Thetransformershall becapableofwithstandingthepowerfre-uencyandimpulsetest)oltage as gi)en in "#$ %0%& ('art(""")/*01* and latest )ersion thereof.15.0 CONSTURCTIONAL FEATURES:"5&" B'()*+, -..-+,/0/+11 A The transformer shall be fitted with three hi(h volta(eand four low volta(e outdoor type bushin( of appropriate volta(e and current ratin(and shall be mounted on side of the tan@ and not on the top cover& The electricalcharacteristics of hi(h volta(e bushin( shall conform to latest version of /0120--&The low volta(e bushin( shall conform to latest version of /01.'2"&"5&2 The dimensions of bushin( shall conform to latest version of /0 mentioned a(ainstthem 178&$& Kushin( 1 /01 '. >;art7/? 0ection " ! 2H&$& Kushin( 1 /01 '. >;art7///? 0ection " ! 2"5& B'()*+, T/.0*+-2(:H To avoid bimetallic action at the point of connection to thealuminium windin(s and to thee6ternal aluminiumcables % conductors,both H$and 8$bushin( stems shall be made of Aluminiumalloy conformin( to there3uirements of /01 '.&"5&' The bushin( terminals shall be clamp type to directly receive aluminiumconductors% cableswithout re3uirin(useof lu(s& Theterminalsshall bedirectlyscrewedontothestemtosecureeffectivesealin(of thebushin(& =etailsofterminals are (iven in 5i(& 4o& ' ! 5&1.0TANK CONSTRUCTION:*&.* The tan2 shall be of rectangular shape with round edges and be fabricated from tested-uality of mild steel of ade-uate thic2ness i.e. minimum 3.*5 mm (for side walls) and5.00 mm (for top and bottom plates).*&.% To meet the )ariation of pressure inside the tan2! due to )ariation in temperature andshort circuit current the tan2 shall be suitably stiffened. The stiffeners shall be pro)idedon all the four side walls of the tan2.*&.3 The transformers tan2 shall be fitted with 45, elliptical tube/pressed steel radiators.6eat dissipation calculation in respect of number! si7e 8 length of radiators are to bepro)ed by design calculation.*&. The tan2 co)er shall be slightly sloping towards 6.9. bushing and shall be thoroughlywelded with the tan2 so that there are no chances of any lea2age.*&.5 The transformer tan2 shall be complete with all accessories and lifting lugs and shall bedesigned so as to allow the complete transformer tan2!filled with oil to be lifted bycraneor:ac2setc. transportedby5ail/5oadwithout strainingany:oint andwithoutcausing lea2age of oil.*&.& The transformer tan2 shall be fitted with s2ids. ;ll s2ids shall be pro)ided with four axleholes of 0 mm diameter (for shaft of 31 mm plain roller).1.# SEALIN" "ASKETS$*&...* ;ll sealing washers/gas2ets shall be made of oil and heat resistant ?# ,>5@"+A of the transformers. The )alue of the flux density allowed inthe design and grade of lamination used shall be clearly stated in the offer.*... ;ll parts of the core shall be of robust design! capable of withstanding any shoc2s to whichtheymaybe sub:ectedduringhandling! lifting! transportationinstallationandser)ice.Clamping of core and winding assembly with tan2 should be done by angle iron pieces!welded to tan2 walls and not to be done with flat iron pieces.*..1 ;de-uate fitments shall be pro)ided to enable the core and winding to be lifted.*..0 Bor the core design! certain details are gi)en below for transformers of rating %5 @9;.Those are the minimum )alues$ C#l. +o. ';5T"C?D;5#D4T;"D# B>5%5 @9; &3 @9; *00 @9;* % 35*. ,eight of core lamination in 2g.&1 *%5 *.0%. Core Clamping(a) Channel si7e(b) Eolt diamm/+os.(c) Tie Eolts.5 x 0 mm*% mm/ %+os.(6igh tensile boltsshall be used inparallel at each end) +os.of *% mmdia M.#. 5od Eoltsto be effecti)elyinsulated.5 x 0 mm*% mm/ %+os.(6igh tensile boltsshall be used inparallel at each end) +os.of *% mmdia M.#. 5od Eoltsto be effecti)elyinsulated.5 x 0 mm*% mm/ %+os.(6igh tensile boltsshall be used inparallel at each end) +os.of *% mmdia M.#. 5od Eoltsto be effecti)elyinsulated(d) Top Fo2e channels to be reinforced by M.#. Blat of 50 mm at e-ual distance! ifholes cutting are done for D.T. leads so as to a)oid bending of channels.(e) CoreEaseandbottomyo2eshall besupportedwith.5mmx0mmM.#.channel properly bolted together. "n no case! Blat or cut channels shall beaccepted.1%.0 BASE MOUNTIN" ARRAN"EMENT$The under base of all transformers shall be pro)ided with two .5x0x& mm! channels withholes (at a center to center distance of *5 mm) to ma2e them suitable for mounting onplatform or plinth (fig. 3).1&.0 CLEARANCES$*0.* 4xternal$ ( The external electrical clearance between phase to phase and phase to earth topro)ide ade-uate creepage distance in accordance with Clause C ..* of "#$ %000 shall not beless than the )alues gi)en below$(9oltage Medium 'hase to 'hase 'hase to 4arth** @933 9olts;ir;ir%55 mm.5 mm%05 mm55 mm*0.% "nternal$( ". Minimum internal clearance between inner walls of tan2 and core coil assembly unitshall be as under$ ((a) >n length side G 0 mm(b) >n width side G %5 mm"". 5adial clearance between 69 8 D9 winding G ** mm. (Eare conductor clearance)""" 'hase to phase clearanceG *0 mm.between 6.9. limbs (Di)e 'art)"9. Minimum clearance from top of yo2e to the inside ofThe top co)er of tan2. G *%0 mm9. Minimum clearance of D9 coil to core (mm) G 5.0 mm.9". Minimum gap between 69 coils (6ori7ontal duct) G 1.0 mm9"". Minimum clearance for 69 coil to lower and upper yo2e G %5 mm.9""". Minimum clearance between core and tan2 bottomG 0 mm.Theaforesaidexternal andinternal clearancesareminimumclearancesandnonegati)etolerance on these clearances shall be allowed.20.0 TEST AND INSPECTION$20.1 ROUTINE TEST$;ll transformers shall be sub:ectedtoroutine tests at the manufacturerHs wor2s. Thefollowing routine tests shall be carried out in accordance with the details specified in thelatest )ersion of "##$ **10/'art("" and "#$%0%& $((a)Measurement of winding resistance(b) Measurement of )oltage ratio! polarity and chec2 of )oltage )ector relationship.(c) Measurement of impedance )oltage / short circuit impedance 8 load loss.(d) Measurement of +o(load loss and +o(load current (e) Measurement of insulation resistance $("nsulationresistance)alueshall bemeasuredwith%5009.Motori7edmeggar)minimumacceptable )alues for insulation resistance D.9. to 4arth at differenttemperature shall be as follows$(T4M'45;T?54M"+"M?M ;CC4'T;ED4 9;D?4%0 Dec.C. *000 M. >hms30 Deg.C. 500 M. >hms."nduced o)er )oltage withstand test(f) #eparate source )oltage withstand test(g) "n addition to abo)e! oil sample drawn from one transformer out of the offered atsupplierHs wor2s shall be tested for following$ ((i) ED9 of oil (fresh from storage of tan2 as well as from transformers)(ii) 5esisti)ity(iii) ;cidity (i)) Tan(DeltaThepurchaser reser)es theright tota2esampleof transformer oil! filedinthetransformer and send them for testing to an institution of repute at the purchaserHscost. The test result shall be binding on the contractor.%0.% The following additional tests shall be performed on one transformer in e)ery offered lot$ ((i)OIL LEAKA"E TEST$Thetransformer withweldedlidandwithall thefittings includingbushinginposition shall be tested for lea2age at a pressure of 10 2pa (0.1 2g/s-.cm.) abo)eatmospheric pressure maintained inside the tan2 for *0 minutes measured at the baseof the tan2. There should be no lea2age at any :oint.NOTE$ ';s the abo)e test is re-uiredtobe carriedout before final sealingof thetransformer the inspection authority would ensure to be present at the time of final sealingto witness this test. The test can be demonstrated on a completed transformer.%0.3 TYPE TESTS$ Theofferede-uipment orthee-uipment ofhighersi7emust bepro)endesignthroughsuccessful type testing as per "#$%0%&/1* or latest amendment thereof during last fi)e yearscountedfromthedateof openingof tender at C'5"! Ehopal or Eangaloreor +.T.6.!Aha7iabad or 45D;! 9adodara in respect of following tests $(>i? All *outine tests as per para 20&" >a? to >h?>ii? )47KA8A4,+= ,)**+4T T+0TThevalueof un7balancedcurrent indicatedbytheammetercorrespondin(tofull loadcurrent onsecondaryshowninthetest arran(ement in5i(& >5?shall not bemore than 29 of the full load current&>iii? /G;)80+ $iv? T+G;+*AT)*+ */0+ T+0TAs per /01 2026%2" >;art7//? and latest amendment thereof at (uaranteed noload plus load losses at "00 =e(&,&>v? 0H4o8oad8osses?50000 >8oad8osses?2&6 2&6 2&6 "&6-SCHEDULE OF "UARANTEED TECHNICAL PARTICULARS A"AINST TENDERSPECIFICATION NO. DVVNL'MM/33'2013 FOR SUPPLY OF THREE PHASEOUTDOORTYPE11/0.433KV40.25KV,25, 3!100KVA ALUMINIUMWOUNDSEALED TYPE DISTRIBUTION TRANSFORMERS$S,.N5.P+*1/6.,+*2*. N+0( 57 M+).7+61.*(*$$%. T89( $3. R+1/):$a) 5ated output (@9;) $b) 5ated 9oltage C 69 (9olts)$$c) 5ated 9oltage ( D9 (9olts) $d) +o load )oltage ratio.$e) +umber of phases $f) Bre-uency (c/s)$. C5))(61/5)2$ a) 6igh )oltage.$$b) Dow )oltage.$$c) 9ector group symbol $5. M(1;5< 57 C55,/):$ a) 'ressed #teel 5adiator ha)ingconnections with tan2 through header.$b) 4lliptical tubes ha)ing connectionswith tan2 through header.$&. I)1(*)+, D/0()2/5)2 57 T+)=$a) Dength (mm.)$b) Ereadth (mm.) $c) 6eight (mm.) $d) Thic2ness of tan2 sheet (mm.) $i)#ide (mm.) $ii) Top 8 Eottom (mm.) $.. D(1+/,2 57 65*($a) Diameter (mm.)$b) Cross #ectional ;rea (mm%)$i) Aross.$ii)+et$c),indow 6eight (mm.)$d)Dimb Centre (mm.)$e) Max. flux density at rated )oltageand fre-uency (Tesla).$f)Material 8 Thic2ness of lamination(mm.)$g) ,eight ofstampingincoreandyo2e separately in 2g.$i)Core (@g.)$ii)Fo2e (@g.) $iii)Total (@g.)$1. HV C5/, C5)21*.61/5) uter Diameter of Coil (mm.) $f) "nner Diameter of Coil (mm.) $g) Mean Diameter of Coil (mm.) $h) "nsulation of conductor. $i) "nter layer reinforcement details $:) Current full load (;mp.) $2) +ormal wor2ing current density (;mp/mm%).$l) 4nd turn insulation $m) ,eight ofbare conductor used in one leg of 69 (@g.)$n) ,eight of insulated conductor used in one leg of 69 (@g.)$o) +o. of turns per leg$p) Dength of mean turns (mm.) $-) *%5 at .50C $r) ;xial Dength (mm.) $s) 5esistance per phase at .5oC (ohms) Maximum.$t) ,t. of winding with insulation in one leg of 69 (@g.)$0. LV C5/, C5)21*.61/5) )$(b) "f Fes! where 8 when was it type testedQ$(i) "mpulse $(ii) #hort Circuit $(c ) "s there any de)iation in the technicalspecification of offered distributiontransformerQ "f yes gi)e details.$