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Dissipation FactorDiss ipat ion fac tor i s a measure of the amo unt of ene rgy tha t i sdissipated into a resin when subjected to an clectr ic f ield. Th ecncrgy dissipated is usually converted in to heat.Dielectr ic ConstantIn th is case mcasurcments wcrc m ade us ing a pa ral le l p la te e lec t rodeconfiguration. Parallcl plates whcn scparat cd by resin yield acapac i tance , An idcnt ica l se t u p wi thout r e s in in a vac uum yie lds asma l le r capac i tance . T hc ra t io of thcsc capac i tances is the diclcctr iccons tant .Thc tc s t ing of diss ipa t ion fac tor and d ie lec t r ic cons tant wercpe r formed s imul tancously in th is case . Th e tc s t sc t up u t i l ir c s agua rded c lcc t rode , a guard r ing e lec t rode and an unguardedc lcc t rodc . Th e unguarded e lec t rode is a d isk 2% inchcs in diameter .The gua rded c lcc t rod c is a d isk 2 inches in d iamete r . The gua rd r ingc lcc t rodc is a r ing wi th an ins idc d iamete r of 2 1/8 nchcs and outs idcdiametcr of 2% inchcs . The e lcc t rodes a re conf igured for tc s t ingsuch tha t the r e s in to bc te s ted is sandwiched be tween the unguardedc lcc t rodc and thc gua rded e lcc t rode .Thc gua rded e lcc t rodc issur rounded by the gua rd r ing c lcc t rode . Th e cente r s of thee lcc t rodcs a rc a l igned on a common axis . The re s in i s a cured shee tof uniform thickncss. Sec Figur es la and l b .Tes t ing can be conduc tcd a t va r ious tempera ture s and f rcquenc ics .In this case tcsting was conduct cd over a range of tcmpcratu res atonc kilohcr(7. Tcsting is cond ucted by attachi ng the unguardedclcctro dc to high lead of the nicasuring dcvicc, thc guardcd clcctro dcto the low lead and thc gua rd r ing clcc t rode to ground. Capac i tanceand dissipation factor rcadings ar c takcn. Since the thickness of thercsin shcct is known, the capacitance of the cxact electrodeconfiguration in vacuum can bc ca lcula tcd . The capac i tance of thcclcctrodc configuration with rcsin as the diclcctr ic is known frommeasurcmcnts . The capac i tance of thc clcctrodc configuration invacuum is de r ived f rom ca lcula t ions . There fore thc d ie lec t r icconst ant of thc resin can be ca lcula tcd .An clectr ical insulating rcsin generally serves one of two purposes 1)to ac t a s a coating that binds parts togcthcr, provides electr icalinsulat ion and environmcnta l pro tect ion or 2) to ac t a s the d ie lec t r icin a capac i tor . In th is caw thc r e s ins sc rvc thc f i r s t purposc . For th isr e ason it is desirahlc to have low diclcctr ic constant values and lowdissipation factor values. A low dissipation factor indicates lesse lec tr ica l ene rgy be ing conver ted in to hea t . A low die lec t ric cons tantindica te s less ene rgy be ing used to cause molecula r a l ignment in theresin under test.

bl 111 b

Electr ical insulation systems testing is a method of thermally ratingt h e m a j o r c o m p o n e n t s of an e lec t rica l produc t such a s a m otor or at ransformer . Major components inc lude insula ting re s in , magne twire, groun d insulation and interwinding insulation. Th e testingoffers a way to predict th e service life of electr ical prod ucts. Inaddi t ion to the rma l degrada t ion , t he te s t ing provides s t r e sses in theform of vibration, cold shock and exposure to 100% relativehumidi ty . These addi t iona l s t r e sses s imula te posss ib leenvironmenta l exposures an e lec t r ica l p roduc t may exper ience inac tua l use . The sp ec imens used in te s t ing a re usua lly non- func t iona lpro to type uni ts .

In th is case a t r ansform ere t te spec imen was used . A t r ansformere t teis cons t ruc ted by winding a b i f i la r magn e t wire co i l onto a groundinsulat ion which is a t tached to a me ta l core . Th e ground insula t ion ishe ld in in t ima te contac t wi th th e core . An interwinding insulation isp laced ove r th is co i l and anothe r b i f i la r co i l i s wound on to thein te rwinding insula t ion . F inal ly , the uni ts a re t r ea ted wi th the r e s into be te s ted . Normal ly , ten uni ts a re buil t pe r te s t tempera ture . Inth is case , however , f ive uni ts were te s ted per tempera ture .Spec imens a re p laced in an oven a t an aging tempera ture andperiodically removed for test. A test cycle consists of one hour ofv ibra t ion , a two hour co ld shock and a 48 h o u r e x p o s u r e t o 100%Rela t ive Humidi ty . At th e end of th is t ime three e lec t r ica l te s ts a repe r formed. Each te s t i s for ten minutes . l h e f i r s t te s t i s 120 voltsappl ied ac ross th e indiv idua l wires of the b i f ila r co i ls. Th e secondtest is 600 vol ts appl ied ac ross the two coils . Th e th ird te s t i s 600vol ts appl ied ac ross the coi ls and the me ta l core . Fa i lure on each te s ti s when a .75 ampe re cur rent i s de tec ted . When fa i lure of any ofthese te s ts occurs a f a i lure t ime is a ss igned to tha t uni t . The fa i luret ime is the midpoin t of the hours of th e la s t ag ing cyc le tha t the u ni tpassed and the cyc le tha t thc uni t f a i led . Tes t ing is conduc tcd a tthree or more tempera tures . In th is way a t ime- tempera turere la t ionship can be deve loped and a temp era ture index can beextrapola ted a t a spec i fic t ime . S imilar , to the the rma l endurancewith f i lm- insula ted magne t wire the indices a re grouped in to c la sses .In th is case two groups of insula tion sys tems were te s ted . The f i r s tgroup employed bas ic components which cons is ted of MW 35magne twire (modif ied polyes te r basecoa t wi th polyamide - imide topcoa tra ted c la ss 200) and a ramid p ape r for both ground and in te rwindinginsulat ion . The grou p was te s ted u t i l izing these basic componentswi th each indiv idua l sys tem be ing d i f f e rent ia ted only by theinsulat ing res in used . Th e second group employed bas ic componentswhich consisted of MW 8 magne t wire (polyure thane basecoa t wi tha polyamide topcoa t r a ted c la ss 130) and a ramid pape r for bothground and in te rwinding insulat ion . Aga in the sys tems in th is groupwere d i f f e rent ia ted by the insula t ing re s in used to t r ea t them.

Th e majo r purpo se of electr ical insulation systems testing is tothe rma lly r a te a group of components ac t ing toge the r . This te s t inga lso ident i f ie s any incompa t ib i li t ie s be tween ma jor componen ts .Examining the te s t procedure , the f i r s t e lect r ical te s t s t r e sses themagne t wire insula t ion and insula t ing re s in . Th e second te st s t r e ssesthe magnet wire insulation, insulating resin and interwindinginsulation. Finally, the third test stresses the magn et wire insulation,insula ting re s in and the ground insula t ion . Thes e te s ts he lp i so la teany weak components or incompatibilities between specif iccomp onen ts. The overall testing is a useful tool in predicting longte rm pe r formance of e lec tr ica l appa r a tus cons t ruc ted wi th the ma jorcomponents te s ted .Figure l a: Face View of Parallel Platc Elcc trodes \

S U M M A R Y OF R E S U L T S. .Vlscositv and Thixotropic IndexTable 1 lists the Brookfield viscosities of the resin and f illercombina t ions and the i r th ixotropic indiccs . Viscos ity va lues a r c incentipoise.

F igure lb : Sidc View of Parallcl Platc Electro dcs252

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RESIN A RESIN B RESIN CII VISCOSITY AT I T H I X O - I VISCOSITY AT I T H I X O - I VISCOSITY AT I T H I X O -I IT R O P l C I ] T R O P I C I ~vTROPIC1 6 r p m I 6 0 r p m I IN D E X I 6 rp m I60 rp m I IN D E X I6 r pm I 6 0 r p m I IN D E XFILLER I @ 25 C I @ 25 C I I @ 2 5 " C I @25'C I 1 @25'C I @ 2 5 " C In o n e

10 % s20 % s30% s4 0 4 s40 % SF4 0 % S H A30 % T

30 036 542 580 0i s o n3800270057600

34 038 042 374 014163450304016640

0.900.961.011.081.101.100.893.50

IIIII1III

21 0 I 23 830 5 I 32 240 0 I 35 545 0 I 45 31200 I 11801400 I 12081100 I 91 838400 I 10240

Table 1 : Viscosities at 25 C in centipciise and thixotrop ic indices.

Ge l TimeTable 2 l i s t the ge l t imes for t h e var ious r e s in under test .

G el T i m e in MinutesTested a t 1 0 0 C

0.880.951.130.991.021.161.203.75

III50 0 1 50 0III3200 I 2656II148110 I 13440I

37 5 1 39 047 5 I 46 0

90 0 I 8101200 I 1154

88 0 I 86 0

0.961.031.001.111.041.201.023.33

FILLER RESIN A RESIN B RESIN CU N F IL L E D I 51.4 I 54.1 1 47.610 % s I1 46.4 II 52.5 II 38.8

I I iI I II I II I I

III I I

20 % s 1 59.8 I 61.1 1 39.630 % s I 60.8 I 52.7 I 39.440 % S I 45.0 I 52.7 I 34.440 % SF 1 57.3 I 49.4 I 23.2

1 25.930 % T I 33.6 I 32.4 I 20.74 0 7 6 S H A 1 40.9 I 59.0

Table 2: Ge l t imes

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T ~ e'rTable 3 lists th e the rma l indices of the various resins testedclcctr ically with MW 35 and MW 80.

Temperature Indices(OC) at 20,000 hoursof Resin and Magne t Wire Combina t ions

T E S T W I T H M W 3 5 T E S T E D W I T H M W 8 0I R E S I N A I R E S I N B 1 R E S I N C I 1 R E S I N A I R E S I N B 1 R E S I N C

F I L L E R 1 I I I 1 I 1n o n cln'% s20 % s30 % s4 0 4 S40% SF4O%,SHA30% T

183.1186.8186.5187.9185.3187.4181.51X4.4

180.8195.1192.8183.9185.3191.3181.2188.0

187.0190.2189.8189.0185.9183.9188.1188.7

156.2163.5155.9160.9165.6159.6158.1156.

Tahlc 3: Therm al Indices at 20,000 hours.

Helical Coil Bond SlrenethgTable 4 lists th e helical coil bond strengths of the va r ious r e s instcsted at 25-C an d 15O0'C.

164.2156.2161.7158.2159.4103.8156.3155.2

150.3157.7156.3159.0152.0149.8144.7144.5

F I L L E R

none10 % s207T s3 0% s40 % s40 % SF40%SHA30 % T

H E L I C A L COIL B O N D S T R E N G T H Sin poundsM A G N E T W I R E - M W 3 5 C U R E D O N E H O U R AT 200'C

I 25OC I I 1 5 0 ~ ~1 R E S I N A . 1 R E S I N B 1 R E S I N C 1 1 R E S I N A I R E S I N B I R E S l N C

II1 3 1 . 0I 22.4I1 35.9

II 33.5I1 35.0II 48.7IIII1 34.3

1 51.4I 42.8I 54.1

32.532.741.5

34 . I27.433.1

31.935.633.137.941.0

43.544.8

I38.9 I

2.62. 22. 13. 33.73.03.43. 5

1. 83.22. 6

5.96. 26.4

IIIII

3. 1 1 6.94. 2 1 7.83.4 1 6. 32. 5 1 6.83.0 1 5.4

Tahlc 4: Helical coil hood s t r cnglhs in pounds .

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Diss ina tion Fac tor and Die lec t ric Co nstantTabld 5 l i s t s d issipa t ion fac tor s and d ie lec t r ic cons tants a t 50 'C ,100OC an d 150'C. Test ing was conduc ted a t 1 ki lohe r tz ove r a r angeof tempera tures but these were se lec ted a s examples .

D I S S I PA T I O N F A C T O R A N D D I E L E C T R I C C O N S T A N T SR E S I N AI D I S SI P AT I O N F A C T O R D I E L E C T R I C C O N S T A N T

IIIIIIIII

n o n e ,0631 0 % , S I ,04420 % s 1 .06630%s I ,0484 0 % S 1 ,04040 % S F I ,03640%SHA 1 ,06030 % T I ,046

,159,164,106.I05. I09,018.135.091

,577.535,405,456,399,062,591,255

3.012.663.102.643.163.582.652.72

3.312.783.422.883.363.712.912 .83

3.833.303.863.104.003.783.453.11

T a b l e 5 : Diss ipa tion fac t or s and d ie lect r ic cons tan ts a t se lec tedt em p er at ur es . p 1 s c u s s O NViscosityAs would be expec ted the addi t ion of inoraganic f i lle r to aninsula ting re s in causes the v iscos i ty to inc rease . Fac tor s such a s eas eof handl ing , pene tra t ion in to windings and bui ld on and electr icalpa r t a f te r d ipping in to a r e s in must be a ssessed . Inc reased v iscos itywil l r educe a r e s ins ab i l i ty t o pene tra te in to a winding whi leinc reas ing the r e s in bui ld on pa r ts tha t a re d ipped in a r e s in . Ease ofhandl ing inc ludes i tems such a s pour ing a r e s in f rom a conta ine r in todipping tank or pumping a r e s in f rom hold ing tanks in to a d ippingtank.Anothe r poin t to note i s the e f fec ts d i f f e rent f i l le r s have on theviscosity of a resin. Th e talc f iller causes a dram atic increa se inviscos i ty . Also , d i f f e rent r e s ins r e spond d i f f e rently t o the samef i l le r . This i s bes t exempl i fied wi th the s la te f lour and the s i l ica andhydra ted a lumina mixture . Th e unf i l led r e s ins have s imi la r v iscos tie sbut when f i l led wi th s la te f lour or s i l ica and hydra ted a lumina theviscos it ie s a re qui te d i f f e rent .

m ginThe combina t ion of r e s in AUF , MW35 and Aramid pap e r i s known top e r f o rm a s a 18 0 class system. Similarly, the combin ation of resinA U F , MW28 and Aramid pape r i s known to pe r form as a 13 0 classsys tem. For r e fe rcnce purposes the tempera ture indices of thesesys tems were de f ined a s 180'C and 130C respec t ively . Tha t i s tosa y t h e h o u r s a t 180OC were de te rmined f rom the t ime- tempera turerelationship of the sys tem with r e s in AU F and MW 35. These hourswere the poin t a t which the tempera ture indices of the r ema iningsys tems wi th MW 35 were de te rmined. In the Same way the hours a t130OC were de te rmined for the sys tem with r e s in A UF and MW 28and these hours w ere the poin t a t which the temp era ture indices ofthe r ema ining sys tems wi th MW 28 were de te rmined. The indices a relisted in Table 6.

Tem pera tu re Indices (OC)of Insula t ion Sys tems Tes tedF I L L E R I Systems wi th I Systems wi thI M W 3 5 I M W 2 8U N F I L L E D 1 180 I 13 0

II

10% s I 182.940 % S I 185.6

130.1142.9

I I40 % S F I 191.2 I 142.940 % S H A I

II 182.9 II 132.8I

30% T I 191.9 I 143.3T a b l e 6: Insulation system temperature indices

Thixotrooic IndexSimilar to the viscosity the thixotrop ic index is heavily effected by thetype of f iller used in a resin. Again the talc shows a dram aticincrease. A s reviewed previously the thixotropic index provides anindication of the draina ge characte ristics of a resin.G e l T i m eA clear patt ern of th e effect of a f iller on an insulating resin's gelt ime cannot be e s tabl ished . Howev er , some obse rva t ions can bem a d e . Inversely, talcexhib i ts the most not icable e f fec t . Th e ge l time of the r e s ins wi th theta lc f i l le r a re r educed s ignif icant ly . Th e e f fec ts also a p p e a r t o b ere la ted to the base r e s in . Any e f fec t of ge l t ime should be ca re fu llyreviewed s ince ge l t ime is an indica tor of pot l i f e and s torage l i f e .Th e e f fec t a f i l le r has on the ge l t ime can be ba lanced by th e addi t ionor subtrac t ion of inhib i tor s tha t he lp contro l ge l t ime and the re forepot life .-Enduaaceed r - M a g n e t W ireIn orde r t o e f fect ive ly eva lua te the impac t of f i l le r s on the th e rma lendurance of a r e s in the d i f f e rences in the tempe r ture indices of th ef i l led r e s ins minus the unfi l led r e s in should be r eviewed. Table 7lists these differences.

It appea r s tha t s i l ica has the leas t e f fec t .

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Dif fe rence in T empe ra ture Indices( OC) a t 20 ,000 hoursof F i l led Res in a s Com pared to Unf i l led Res in~~~

I T E S T W I T H M W 35 1 I T E S T E D W l T H M W 8 0I R E S I N A I R E S I N B I R E S I N C I 1 R E S I N A I R E S I N B I R E S I N C

F I L L E R I I I I 1 I I

10 % s20 % s3w%s40 % s40% SF4 0 % S H A30% T

3.73.44 82. 24 .3-1.61. 3

8. 36. 0-2.9-1 .54. 5-5.61. 2

3. 22. 8

I7.5 I

IIIIIIII

7.3 1 -8.0-0.3 I -2.54. 7 1 -6 .09.4 I -4.83.4 I -0.41.9 I -7.9

-0.1 1 -9.0

7. 46.08.7I .7

-0.5-5.6-5.8

T a b l e 7: Dif fe rences of Temp era ture Indices a t 20,000 hours .Anothe r impor tant a spec t of the rma l endurance te s t ing is the ac tua lthe rma l c la ss of a tempera ture index.

Thermal C lass of Tem pera tu re Indices( "C) a t 20,000hoursof Resin and Magnc t Wirc Combina t ionsI T E S T W I T H M W 3 5 I I T E S T E D W l T H M W 8 0

~~ ~~ ____I RESJN A I R E S I N B I R E S I N C I I R E S I N A I RESIN B 1 RESIN CF I L L E R I I I I I I IN O N E10 % s20 % s30 % s40 % s

4 0 % S F40 % SH A3 0 % T

18018 018 0180180

180180180

I8 0 I 18 0 I I 155I I I18 0

18 0180180

18 018 018 0

18 0 II

180 II18 0 II180 II

180 I18 018 0

15 5155155155155155155

155 I 13 0155 I 15 5I

IIIIII

155 1 155155 I 155155 1 13 0155 I 13 015 5 I 130155 I 13 0

T a b l e 8: Thermal C lass of Te mpera ture Indices a t 20 ,000 hours .

F rom the d i f f e rences of the of the temp era tur e indices a c lea rpa t te rn i s not ev ident. However , the ac tua l tempera tu re indices a rera rely comp ared . In prac t ice the the rma l c la sses a re compared . Inexamining the the rma l c la ss i t i s seen tha t the add i t ion f i l le r in thesecases does not change and in three cases ac tua l ly r a ise s the the rma lclass as compared to the resin with no f illcr .f I el i ca l C o i l B o n d S t r e n e hIn reviewing the helical coil bond strength results it i s seen tha t thebond s t r ength of resins with f iller excede that of the resin with nof iller in 36 of the 42 cases . In the r ema ining s ix cases the la rges td i f f e ren ce s 2 .4 poun ds which fgl ls wi th in the va r ia t ion seen be tweentest of the same re s in . This seems to indica te tha t the addi t ion off i l le r to a r e s in a t the ve ry leas t does not d iminish the cured re s insphysica l in tegr i ty . in most cases th e f i l le r ac tua l ly augmen ts theresins bonding ability.

Diss ipa tion Fac tor and Die lec t ric Con stantThe va r ia t ions of diss ipat ion fac to r and d ie lec t r ic cons tant be tweenthe d i f f e rent resins tested is clearly illustrated by the plots of t h ediss ipa t ion fac tor and d ic lec t r ic cons tant ve r sus tempera ture .F igures 2 and 3 a re d iss ipa t ion fac tor ve r sus tempera ture whi lef igures 4 an d 5 a re d ie lec t ric cons tant ve r sus tempcra turc .

I n genera l , a s seen f rom f igures 2 and 3 a drop in the d iss ipa t ionfactor is evident. T h e s l a t e f lour has the most noticable e ffec t . Thehas a s ignif icant e f fec t and s i l ica has some e f fec t . The silica andhydra ted a lumina combina t ion has the leas t e f fec t .Th e d ie lec t r ic cons tant r e su l ts d o not present a s c lear a pa t te rn .However , i t i s in te re s t ing to note the cons is tency of the dielectr iccons tant of the s la te f lour f i l led r e s in ove r the en t i r e tempera turerange te s ted . Examining the r e sul ts the re i s l i tt le va ria t ion be tweenthe unfilled resins and the silca f illed resins. The talc and the silicaand hydra ted a lumina seem to cause a s l ight dro p in the d ie lect r iccons tant f rom the unf i l led r es in . Th e re s in wi th s la te flour is highera t the lower tempera tures but lower a t the h ighe r tempera tures .

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D I S S I P A T I O N F AC TO R v a . T E M P E R A T U R E.-AUF a t i knz- A 2 0 9- A 3 0 S--.-A A 0 8

Figure 2: Diss ipa tion Fac tor ve r sus Tcmp cra turc ( "C)

LOlo D I E L E C T R I C C O NS T AN T v u . T E M P E R A T U R E-WF at I kH z- A40SF- A 4 0 S H A--A 3 0 TFigure 5: Die lect r ic Con stant ve r sus Tempera ture ( 'C )

D I S S I P A T I O N F AC TO R v a . T E M P E R A T E

PAU F a t 1 kHZ- - AAOSF

--A A 0 SHA- - - A30T

.lY

. 4I e m t i o nFrom a brief review of the insula t ing sys tems re sul ts i t can be seentha t the sys tems wi th f i l led r es ins pe r form be t te r than than th esys tems wi th the unf i l led r e s in . I t should be noted tha t in each groupof sys tems a l l sys tems would be grouped in the s ame the rma l c la ss .Th e ta lc and s la te f lour f i l led ve r s ions pe r form s ignificant ly be t te rthan th e unf il lcd ve r sion in both g roup of systems.,,/,/CONCLUSIONSInorganic f i l le r s a re known to enhan ce the the rma l conduc t iv i ty of anelectr ical insulating resin which will a id the resins ability to dissipatehea t away f rom an e lec t r ica l produc t. Var ious f i l le rs may provideothe r advantages . For example ta lc inc reases th e th ixotropoc indexof resins which may provi de an advantage in certain circumstances.Hydra ted a lumina provides r e s ins wi th f lame re ta rda nt qua l i t i te s

which may be use lu l . A poss ib le d isadvantage of f i l le r s i s tha t thef i l le r s may se t t le out of the r e s in and require ag i ta t ion t o r ema insuspended.

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