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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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4

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'

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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