The magnetic circuit
By: by V. Karapetoff.
Publisher: McGraw-Hill Book Company
Published: 1911
Place of publication: New York; London
Language: eng
Number of pages: 283
Subjects: Electric machinery.; Electrodynamics.; Electromagnetism.
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CONTENTS 

PAGE 

Preface v 

Suggestions To Teachers xi 

Chapter I. The Fundamental Relation Between Flux And Mag- 

Netomotive Force 1 

A simple magnetic circuit. Magnetomotive force. Magnetic flux. 

The reluctance of a magnetic path. The permeance of a magnetic 

path. Reluctivity and permeability. Magnetic intensity. Flux 

density. Reluctances and permeances in series and in parallel. 

Chapter II. The Magnetic Circuit With Iron 20 

The difference between iron and non-magnetic materials. Mag- 

netization curves. Permeability and saturation. Problems involv- 

ing the use of magnetization curves. 

Chapter III. Hysteresis And Eddy Currents In Iron 32 

The hysteresis loop. An explanation of saturation and hysteresis 

in iron. The loss of energy per cycle of magnetization. Eddy cur- 
rents in iron. The significance of iron loss in electrical machinery. 
The total core loss. Practical data on hysteresis loss. Eddy cur- 
rent loss in iron. The separation of hysteresis from eddy currents. 

Chapter IV. Induced E.M.F. In Electrical Machinery 55 

Methods of inducing e.m.f. The formulae for induced e.m.f. 

The induced e.m.f. in a transformer. The induced e.m.f. in an 
alternator and in an induction motor. The breadth factor. The 
slot factor ks. The winding-pitch factor kw. Non-sinusoidal vol- 
tages. The induced e.m.f. in a direct-current machine. The ratio 
of A.C. to D.C. voltage in a rotary converter. 

Chapter V. Exciting Ampere-turns In Electrical Machinery .... 80 

The exciting current in a transformer. The exciting current in a 

transformer with a saturated core. The types of magnetic circuit 

occurring in revolving machinery. The air-gap ampere-turns. The 

method of equivalent permeances for the calculation of air-gap 

ampere-turns. 

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Chapter VI. Exciting Ampere-turns In Electrical Machinery. 

(Continued) 100 

The ampere-turns required for saturated teeth. The ampere- 

turns for the armature core and for the field frame. Magnetic 

leakage between field poles. The permeance and reluctance of irreg- 
ular paths. The law of flux refraction. 

Chapter VII. Magnetomotive Force Of Distributed Windings ... 121 

The m.m.f. of a direct-current or single-phase distributed wind- 

ing. The m.m.f. of polyphase windings. The m.m.fs. in a loaded 
induction machine. The higher harmonics of the m.m.fs. 

Chapter VIII. Armature Reaction In Synchronous Machines. . . . 139 

Armature reaction and armature reactance in a synchronous 

machine. The performance diagram of a synchronous machine 

with non-salient poles. The direct and transverse armature reac- 

tion in a synchronous machine with salient poles. The Blondel 

performance diagram of a synchronous machine with salient poles. 

The calculation of the value of the coefficient of direct reaction. The 

calculation of the value of the coefficient of transverse reaction. 

Chapter IX. Armature Reaction In Direct-current Machines .... 163 

The direct and transverse armature reactions. The calculation 

of the field ampere-turns in a direct-current machine under load. 

Commutating poles and compensating windings. Armature reac- 

tion in a rotary converter. 

Chapter X. Electromagnetic Energy And Inductance 177 

The energy stored in an electromagnetic field. Electromagnetic 

energy expressed through the linkages of current and flux. Induc- 

tance as the coefficient of stored energy, or the electrical inertia of a 

circuit. 

Chapter XI. The Inductance Of Cables And Of Transmission 

Lines 189 

The inductance of a single-phase concentric cable. The mag- 

netic field created by a loop of two parallel wires. The inductance 

of a single-phase line. The inductance of a three-phase line with 

symmetrical and semi-symmetrical spacing. The equivalent reac- 

tance and resistance of a three-phase line with an unequal spacing of 

the wires. 

Chapter XII. The Inductance Of The Windings Of Electrical 

Machinery 208 

The inductance of transformer windings. The equivalent leak- 

age permeance of armature windings. The leakage reactance in 

induction machines. The leakage reactance in synchronous machines. 

The reactance voltage of coils undergoing commutation 

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PAGE 

Chapter XIII. The Mechanical Force And Torque Due To Elec- 

Tromagnetic Energy 240 

The density of energy in a magnetic field. The longitudinal 

tension and the lateral compression in a magnetic field. The deter- 

mination of the mechanical forces by means of the principle of virtual 

displacements. The torque in generators and motors. 

Appendix 1 262 

Appendix II . 266