Electrical Machine Design: The Design and Specification of Direct and Alternating Current Machinery

548 Pages·35.929 MB·English

by  Gray A., Lincoln P.M.

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ELECTRICAL MACHINE DESIGN
PUBLISHERS OF &OQK.S
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ELECTRICAL MACHINE
DESIGN
THE DESIGN AND SPECIFICATION OF
DIRECT AND ALTERNATING CURRENT MACHINERY
BY
ALEXANDER GRAY
WHIT Sen M He,
,
I'ltOKUHHOU()li%HWM'TllirU^KNUINKKIUNU
COUNliUj UXIUittHn'Y
MITHOItOKIMtlNCU'LKH ANDI'KAC'TU'WOK
CTJ'X!T1U('A,LKN(UN15KKIN(1
FIHBTEDITION
McGRAW-HILL BOOK COMPANY, INC.
NEW YORK; 370 SEVENTH AVENUE
LONDON:6<feHBOIIVKIUKHT.tE.0,4
1913
COPYRIGHT, 1913, niTUB
BOOKCOMIW
PREFACE
The following work was compiled as a course of lectures on
Electrical Machine Design delivered at MoGill University. Since
the design of electrical machinery is us much an art as ii science
no list of formula or collection of data is sufficient to enable one
to become a successful designer. There is a certain amount of
data, however, sifted from the mass of material on the subject,
which every designer finds convenient to compile for ready
reference. This work contains data that the author found
necessary to tabulate during several years of experience as a
designer of electrical apparatus.
A study of design Is of the utmost importance to all students,
because only by such astudy can a knowledge of the limitations
of machines be acquired. The machines discussed are those
which have become more or less standard, namely, direct-cur-
rent generators and motors, alternating current generators, syn-
chronous motors, polyphase induction motors, and transformers;
other apparatus seldom offers an electrical problem that is not
discussed under one or more of the above headings.
The principle followed throughout the work is to build up the
design for the given rating by the use of a few fundamental
formula*, and design constants, the meaning and limits of which
are discussed thoroughly, and the same procedure has been
followed for the several pieces of apparatus.
The author wishes to acknowledge his indebtedness to Mr.
B. A. Behrond, under whom he learned the first principles of
eleetiical design and whoso influence will be seen throughout the
work; to the engineers of the Allls-(Chalmers-Bullock Company
of Montreal, Canada, and particularly to Mr. Bradley T. M,c-
Cormirk, Mr. U. P. Cole and Mr. II. P. Kilers; to Mr. A. Me-
Naughton of MeOill University for criticism of the arrangement
of the work and to Mr, A, ML B Boycl for awsinUwicointhe proof-
reading,
UNIVKIWITY,
S3,
CONTENTS
SIOOTION 1
BDRECT-CURRENT MACHINERY
CHAPTER
1
PAUM
MAGNETIC INDXIVTJON , 1
Lines of Koree--Direction of tin Klectiio Current -Magnetic Field
Surrounding a (\Kmduotor-"-Magneto Induciion Direction ofthe
Generated K. M. -Magnetomotive Force.
(CHAPTER II
ARMATUUK WINDING 7
,
Gramme Winding H<*-ontnincy Objections to the Gramme
-Drum Wltuling 10.AI.F. J0(j[uai.i()n Multipolar Ma-
H !0<iuulissor (\>nn(H'tionK ~Sliori Piteli WinilingK Mul-
tiple Windin^K -S(vri<kH Windings -Lap and Wave Windings
Shop Instructions -Several Coils in a Slot- -Number of Hlots-
l)dd Windings.
CHAPTER HI
HTUTHT'rroN OF 'MACIUNKH 124
Armature Poles w"Yolu%- (\>tninutator ~Hearings- Slide Itaily
Larg<v Machines.
CHAPTER IV
.*.,.
30
Materials"'-Thickness- -"Heat and Vibration - Grounds and Short-
oireuits--Slot Insulation - 'l*unctur<tTest Mnd(1onn(H",tion Insula-
tion '"Surface Leakage Several Coils in, a Slot -JlOxaiuples of
Armature ami Field Coil Insulation.
CHAPTER V
Tut; MACINKTKI COUHUT, 42
Lea,k,g<s Factor Magnetic Areas ~-Krinjj;injjj CoiwUiut Khix
,I)enHttic*H -'Culeulatioutfthe N(>Mloa<l SaturationCurve andof the
Leakage Factor,
CHAPTER VI
.**,..........
AHMA.TUUK KKA*TION 54
.
Armuturt) Iteuctiou Flux Dintribtition in th Air (Sap " Arnmturo
Kmellon when the Bruwhen are ShiftedFull Load Saturation
*" lielatlve Strungth of l'l<jld and Armature.
vii
CONTENTS
vili
CHAPTER VII
FAIM
DESIGN OP THE MAGNETIC CIBCUIT <>2
Field Coil Heating Size of Field Wire Length of .Field Coils-
Weight of Field Coils Design of the Field System for a Given
Armature.
CHAPTER VIII
COMMUTATION 72
Resistance Commutation Effect of the Self-induction of the Coils
Current Density in the Brush Reactance Voltage Brush Con-
tact Resistance- Energy at the Brush Contact - Reactance
Voltage for Full Pitch Multiple, Short Pitch Multiple and Series
Windings.
CHAPTER IX
COMMUTATION (Continued) 85
Sparking Voltage Minimum Number of Slots per Pole - Brush
Arc Limits of Reactance Voltage Limit ofArmature Loading-
Interpole Machines Interpole Dimensions- Flashing Over,
CHAPTER X
EFFICIENCY AND LOSSES 1)7
Efficiency -Bearing FrictionBrush Friction Windage LOHK-
Iron Losses Armature Copper LossField Copper LOHS Brush
Contact Resistance Loss.
CHAPTER XI
HEATING 104
Temperature Rise Maximum Safe Temperature--Temperature
Gradient in the Core Limiting Values of Flux Density Heating
of Winding Temperature Gradient in the Conductors Commu-
tatorHeating Application of the Heating Constants,
CHAPTER XII
PROCEDURE INARMATURE DJQBIGN ... 114
The OutputEquation- -Relation Between Diameterand Lengthof
the Armature Magnetic and Electric Loading Formulas for
Armature Design Examples of Armature Design,
CHAPTER XIII
MOTOR DESIGNAND RATINGS 127
, . . . ,
Procedurein Design- Ratingsfor DifferentVoltagesand SpoedH
Enclosed Motor Possible Ratingsfora Given Armature.
CHAPTER XIV
LIMITATIONS IN DESIGN 13H
Reactance VoltageandAverage VoltageperBarHighVoltage