edwin beee unit 2

8/20/2019 Edwin Beee Unit 2

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UNIT II

Electrical Mechanics

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CONTENTS

Construction of DC machine

Working principle of DC generator

2EE 6!1 Electrical machines "Iunit # DC motors


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DC Machine Construction

$EE 6!1 Electrical machines "Iunit # DC motors


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DC machine stator with poles visible.

EE 6!1 Electrical machines "Iunit # DC motors


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Rotor of a dc machine

%EE 6!1 Electrical machines "Iunit # DC motors


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Cutaway view of a dc machine

6EE 6!1 Electrical machines "Iunit # DC motors


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Working principle of DC generator

&EE 6!1 Electrical machines "Iunit # DC motors


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Con'ersion of (C to DC

)EE 6!1 Electrical machines "Iunit # DC motors


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Construction of DCgenerator

• ( DC generator has the follo*ingparts

• 1+ ,oke

• 2+ -el. s/stem

• $+ (rmature

•

+Commutator• %+ 0rushes



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,oke

• ,oke of DC generator ser'es t*o purposes

• 3i+ It hol.s the magnetic pole cores of thegenerator an. acts as co'er of the

generator4 3ii+ It carries the magnetic -el.5u4

• In small generator /oke are ma.e of castiron4 Cast iron is cheaper in cost

• lighter cast steel or rolle. steel isprefera7le for constructing /oke of largesi8e DC generator4


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9iel. s/stem

• The pole core is -e. to the inner peripher/ ofthe /oke 7/ means of 7olts through the /oke an.into the pole 7o./4

• The pole shoes are so t/picall/ shape. thatthe/ sprea. out the magnetic 5u in the air gapan. re.uce the reluctance of the magnetic path4

• The -el. coils or pole coils are *oun. aroun. thepole core4 These are a simple coil of insulate.copper *ire or strip *hich place. on the pole*hich place. 7et*een /oke an. pole shoes


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• The purpose of armature core is tohol. the armature *in.ing

• (rmature *in.ing are generall/forme. *oun.4 The con.uctors areplace. in the armature slots *hichare line. *ith tough insulating

material4


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Commutator

• It collects current from armature an.sen.s it to the loa. as .irect current4It actuall/ takes alternating current

from armature an. con'erts it to.irect current an. then sen. it toeternal loa.4


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http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/


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0rushes

• The 7rushes are ma.e of car7on4 These are rectangular 7lock shape.4 The onl/ function of these car7on

7rushes of DC generator is to collectcurrent from commutator segments4

The 7rushes are house. in the

rectangular 7o shape. 7rush hol.er


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http://www.electrical4u.com/principle-of-dc-generator/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/electric-current-and-theory-of-electricity/http://www.electrical4u.com/principle-of-dc-generator/

edwin beee unit 2

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