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^ACULTY OF A. 



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PRINCIPLES 

 OF ELECTRICAL DESIGN 



CHAPTER I 

 INTRODUCTORY 



By devoting a whole chapter to introductory remarks and 

 generalities which are rarely given a prominent place in modern 

 technical literature, the author hopes not only to explain the 

 scheme and purpose of this book, but to show what may be 

 gained by an intelligent study of the conditions to be met, and 

 the difficulties to be overcome, by the designer of electrical 

 machinery. 



The knowledge required of the reader includes elementary 

 mathematics, the use of vectors for representing alternating 

 quantities, the principles of electricity and magnetism, and 

 some familiarity with electrical apparatus and machinery, 

 such as may be acquired in the laboratories of teaching institu- 

 tions equipped for the training of electrical engineers, or in the 

 handling and operation of electrical plant in manufacturing 

 works and power stations. The principles of the magnetic 

 circuit will be explained here in some detail, because the whole 

 subject of generator design from the electrical standpoint is 

 little more than a practical application of the known laws of 

 the electric and magnetic circuits; but a fair knowledge of the 

 physics underlying the action of electromagnetic apparatus is 

 presupposed. 



The conception of the magnetic circuit consisting of closed 

 lines or tubes of induction linked with the electric circuit 

 involving the cutting of these magnetic lines by the conductors 

 in which an e.m.f. is generated is unquestionably a useful one 

 for the practical engineer; and the student should endeavor to 

 form a mental picture of these imaginary magnetic lines in 

 connection with every piece of electrical apparatus or machinery 

 which he desires to understand thoroughly. 



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