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DC MOTOR
Soedibyo
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References
1. Theraja, B. L., Elecrical Technolo!y", S.
Chand # Co$%any Ld., 1&'(.
2. Sch$id)*aler, +., ories, R., Elecrical
En!ineerin!- /oc0e Reference", rech+ose nc., 233'.
4. Cha%$an, S. 5., Elecric Machinery
6nda$enals", Mc7ra8)+ill, 2339.
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DC Moors Olines
13- .Dc $oor-
..dc $oor %ars # 8or0s
..bac0 e$f
..$oor e:i;alen circi
..characerisics of dc $oor- Ta~Ia and n~E/
.Dc shn $oor-..characerisics of dc shn $oor..s%eed conrol of dc shn $oor- n < => ? aRa@A
11- .Dc series # co$%ond $oor
..characerisics of dc series # co$%ond $oor-
Ta~Ia and n~E/..s%eed conrol of dc shn $oor- n < => ? aRa@A
12- .Bra0in! # sarin! of dc $oor
.Dc $oor %o8er sa!es
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dc series motor
V
s
Ta/Iacharacteristic
Ia
Ta
n/IacharacteristicIa
n
Starting point
Nominal point
nn
In
n/Tacharacteristic
n
Ta
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Shn ;s series ;s co$%ond
C$lai;ely co$%ond-
.li0e series $oor- i has
era or:e for sarin!.
.li0e shn $oor- i
doesn" o;ers%eed a no
load
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Re;isions # Las Tas0s
Moor in a car oy )F dc shn $oor
2)24
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Toal Loss in a DC $achine =1@
Toal Losses
Co%%er Losses
ronAMa!neicLosses
Mechanical
Losses
r$are C
Loss
6ield C Loss
hyseresis
Eddy crren
fricion
8inda!e
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Toal Loss in a DC $achine =2@
The losses in a dc $oor are he sa$e as in !eneraor.
a. Co%%er losses =C losses@
.r$are co%%er loss G a2Ra
.6ield co%%er loss G f2Rf
.Loss de o brsh conac resisanceH sally inclded in
he ar$are co%%er loss.
b. ronAMa!neic losses
.+yseresis loss
.Eddy crren loss
c. Mechanical losses
.6ricion loss a bearin!s and co$$aor
.ir)fricion or 8inda!e loss of roain! ar$are
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&
ronAMa!neic Losses
Ener!y Con;ersion
Elecrical
Ener!y
Mechanical
Ener!yElecro$a!neis$
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Toal Loss in a DC $achine =1@-
ron Loss in r$are
De o he roaion of he iron core of he ar$are in he $a!neic
fl, here are so$e losses a0in! %lace coninosly in hecore- Iron Losses or Core Losses.
1. Hysteresis Loss
2. Eddy Current Loss
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+yseresis Loss =1@
..
.
Ma!neic do$ains oriened rando$ly Ma!neic do$ains lined % in he
%resence of an eernal $a!neic field
.*hen he eernal $a!neic field is re$o;ed, he do$ains don" co$%leely
rando$iIe a!ain.
Becase rnin! he$ bac0 requires energy.
.The fac ha rnin! do$ains in he iron re:ires ener!y leads o a co$$on
ener!y loss in all $achines and ransfor$ers )F hyseresis loss.
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+yseresis Loss =2@. /1-boh field sren!h and fl densiy are
Iero.
.The field sren!h is increased in he%osii;e direcion and he fl be!ins o !ro8
alon! he doed %ah nil 8e reach /2.
This is called he initial magnetization curve.
.*hen he a%%lied field is rerned o Iero
here 8ill sill be a re$ainin! =remnant or
remanent@ fl densiy a /4.
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+yseresis Loss =4@
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+yseresis Loss =4@
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Eddy Crren Loss
.The core $aerial is elecrically condci;e.
.*hen i roaes, i also cs he fl.
.+ence, an e$f is indced in he body of he core.
.This e$f ses % crren in he body of he core..
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1
Eddy Crren Loss
.The core $aerial is elecrically condci;e.
.*hen i roaes, i also cs he fl.
.+ence, an e$f is indced in he body of he core.
.This e$f ses % crren in he body of he core..
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1'
Mechanical Loss
.6ricion loss a bearin!s and co$$aor
.ir)fricion or 8inda!e loss of roain! ar$are
Commutator
Poles
Rotor winding
Fan
Bearing
Brushes
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1(
Toal Loss in a DC $achine
Toal Losses
Co%%er Losses
ronAMa!neic
Losses
Mechanical
Losses
r$are C
Loss
6ield C Loss
hyseresis
Eddy crren
fricion
8inda!e
Stray Losses: sally $a!neic and $echanical losses are
colleci;ely 0no8n as Sray Losses.
Constant Losses: *c, consiss of sray losses and shn C
losses.
Variable Loss: ;aried 8ih he load crren )F ar$are C loss.
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1&
DC $achine Consan Losses
.f a $oor rns on no)load a raed s%eed, hen here is no
o% %o8er.
.f he C losses are sbraced fro$ he in% %o8er of he
$oor,
.The re$ainin! in% %o8er $s consis of he $echanical
and core losses.
.These losses are ass$ed consan nder load condiion.
Constant Losses =
Noload In!ut " Cu Losses
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Moor /o8er Sa!es
Motor Input
VI Watt
CopperLosses
Driing po!erin armature
EIaWatt
Iron and "rictionLosses
#utput
$%
#otal Losses = Constant Losses $ Variable Losses
Constant Losses = Noload In!ut " Cu Losses
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)Ende)
2)(
2)21
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2)22.
The in% o a 223)> dc shn $oor is 11 0*.
The no)load crren G 9 H no)load s%eed G 1193 r%$H
RaG 3.9 H RfG 113 H
Calclae-
a. Tor:e de;elo%ed
b. Efficiency
c. S%eed a his load
Solution
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2)4.
Solution
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)EJDE)
6i!res-
ron core
La$inaed iron core
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ndced e.$.f
i. Dyna$ically indced- field issaionary # condcors c across i)F dc !eneraors
ii. Saically indced- condcorAcoilre$ains saionary # fl lin0ed 8ih
i is chan!ed by chan!in! hecrren %rodcin! his fl )Fransfor$ers
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2
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2'
Elecric Bra0in!RheosaicADyna$ic Bra0in!
/l!!in!AConer)crren bra0in!
Re!enerai;e bra0in!
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2(
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2&
Elecric Bra0in! of Shn Moors
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