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Lecture 14: Alternating Current Railway Motor

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FieldValue
SourceGeneral Lectures on Electrical Engineering
Year1908
Section IDgeneral-lectures-electrical-engineering-lecture-14
Locationlines 8649-9342
Statuscandidate
Word Count4794
Equation Candidates In Section10
Figure Candidates In Section0
Quote Candidates In Section0
FOURTEENTH LECTURE ALTERNATING CURRENT RAILWAY MOTOR. mN a direct current motor, whether a shunt or a series motor, the motor still revolves in the same direction, if the impressed e. m. f. be reversed, as field and arma- ture both reverse. Since a reversal of voltage does not change the operation of the motor, such a direct current motor there- fore can operate also on alternating current. With an alter- nating voltage supply, the field magnetism of the motor also alternates ; the motor field must therefore be laminated, to avoid excessive energy losses and heating by eddy currents (cur- rents produced in the field iron by the alternation of the mag- netism) just as in the direct current motor the armature must be laminated. In the shunt motor — in which the supply current
FOURTEENTH LECTURE ALTERNATING CURRENT RAILWAY MOTOR. mN a direct current motor, whether a shunt or a series motor, the motor still revolves in the same direction, if the impressed e. m. f. be reversed, as field and arma- ture both reverse. Since a reversal of voltage does not change the operation of the motor, such a direct current motor there- fore can operate also on alternating current. With an alter- nating voltage supply, the field magnetism of the motor also alternates ; the ...
... the impressed e. m. f. be reversed, as field and arma- ture both reverse. Since a reversal of voltage does not change the operation of the motor, such a direct current motor there- fore can operate also on alternating current. With an alter- nating voltage supply, the field magnetism of the motor also alternates ; the motor field must therefore be laminated, to avoid excessive energy losses and heating by eddy currents (cur- rents produced in the field iron by the alternation of the mag- netism) just as in the direct current motor the armature must be l ...
FOURTEENTH LECTURE ALTERNATING CURRENT RAILWAY MOTOR. mN a direct current motor, whether a shunt or a series motor, the motor still revolves in the same direction, if the impressed e. m. f. be reversed, as field and arma- ture both reverse. Since a reversal of voltage does not change the operation of the motor, ...
... current to lag, and so lowers the power factor of the motor; that is, causes the motor to take more volt-amperes than corresponds to its output, and so is objectionable. The useful voltage, or e. m. f. of rotation of the motor, is proportional to the speed ; or rather the "frequency of rota- tion", No, is proportional to the field strength F, and to the number of armature turns m. The wattless voltage, or self- induction of the field, is proportional to the frequency N, to the field strengfth F, and the number of field turns n. The ratio of the useful ...
Concept CandidateHits In SectionStatus
Frequency12seeded
Ether2seeded
Term CandidateHits In SectionStatus
ether2seeded
Candidate IDOCR / PDF-Text CandidateSource Location
general-lectures-electrical-engineering-eq-candidate-0095tion : armature turns m to field turns n = 2 -4- i ; and at thisline 8744
general-lectures-electrical-engineering-eq-candidate-0096No = 2 N, it must be twice ; at double synchronism :line 9104
general-lectures-electrical-engineering-eq-candidate-0097No = 2 N, it must be one-half the main field.line 9105
general-lectures-electrical-engineering-eq-candidate-0098At half synchronism, No = 2 ^’ ^^^ transformer field ofline 9181
general-lectures-electrical-engineering-eq-candidate-0099the commutating field required Fo = 2 F, and the short cir-line 9183
general-lectures-electrical-engineering-eq-candidate-0100At double synchronism : No = 2 N, the transformer fieldline 9188
general-lectures-electrical-engineering-eq-candidate-0101is F* = 2 F, while the commutation field should be:line 9189
general-lectures-electrical-engineering-eq-candidate-0102Fo = 2 ^» ^^^ the transformer field thus is four times largerline 9190
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