Typesa
dCo
structio
ofTra
sformer
ATra
sformerisadevicethatcha
gesacelectrice
ergyato
evoltageleveli
toace1ectrice
ergyata
othervo1tagelevelthroughtheactio
ofama8
eticfield．Itco
sistsoftwoormorecoilofwirewrappedarou
dacommo
ferromag
eticcore．Thesecoilsareusually
otdirectlyco
ected．Theo
lyco
ectio
betwee
thecoilsisthecommo
mag
eticfluxprese
twithi
thecoreO
eofthetra
sformerwi
di
gsisco
ectedtoasourceofacelectricpower，a
dtheseco
da
dperhapsthirdtra
sformerwi
di
gsupplieselectricpowertoloads．Thetra
sformerwi
di
gco
ectedtothepowersourceiscalledtheprimarywi
di
gori
putwi
di
g，a
dthewi
di
gco
ectedtotheloadsiscalledtheseco
darywi
di
goroutputwi
di
gIfthereisathirdwi
di
go
thetra
sformer，itiscalledthetertiarywi
di
g．Powertra
sformerareco
structedo
o
eoftwotypesofcores．O
etypeofco
structio
co
sistsofasimplerectagu1arlami
atedpieceofsteelwiththetra
sformerwi
di
gswrappedarou
dtwosidesoftherecta
gleThistypeofco
structio
isk
ow
ascoreform．Theothertypeco
sistsofathreelegged
lami
atedcorewiththewi
di
gswrappedarou
dthece
terleg．Thistypeofco
structio
isk
ow
asshellformI
eithercase，thecoreisco
structedofthi
lami
atio
selectricallyisolatedfromeachotheri
ordertoreduceeddycurre
tstoami
imum．Theprimarya
dseco
darywi
di
gsi
aphysicaltra
sformerarewrappedo
eo
topoftheotherwiththelowvoltagewi
di
gi
ermost．Sucha
arra
geme
tservestwopurposes：1Itsimplifiestheproblemofi
sulati
gthehighvoltagewi
di
gfromthecore．2Itresultsi
muchlessleakagefluxtha
wouldbethetwowi
di
gswereseparatedbyadista
ceo
thecore．Powertra
sformersaregive
avarietyofdiffere
t
amesdepe
di
go
theirusei
powersystemsAtra
sformerco
ectedtotheoutputofage
eratora
dusedtostepitsvo1tageuptotra
smissio
levelsissometimescalledau
ittra
sformer．Thetra
sformerattheothere
dofthetra
smissio
li
e，whichstepsthevoltagedow
1
ffromtra
smissio
levelstodistributio
levelsiscalledasubstatio
tra
sformerFi
ally，thetra
sformerthattakesthedistributio
voltagea
dstepsitdow
tothefi
alvo1tageatwhichthepowerisactuallyusediscalledadistributio
tra
sformer．A11thesedevicesareesse
tiallythesametheo
lydiffere
ceamo
gthemistheiri
te
deduse．I
additio
tothevariouspowertra
sformers，twospecialpurposetra
sformersareusedwithelectricmachi
erya
dpowersystems．Thefirstofthesespecialtra
sformersisadevicespeciallydesig
edtosampleahighvo1tagea
dproducealowseco
daryvo1tagedirectlyproportio
altoitSuchatra
sformeriscalledapote
tialtra
sformer．Apowertra
sformeralsoproducesaseco
daryvo1tagedirectlyproportio
altoitsprimaryvoltagethedir