STANDARDIZATION RULES OF THE A. I. E E. 



Ai'i'Mtixi-n 1 1 M '.'7, I'M 1 



I DEFINITIONS AND TECHNICAL DATA 



1 Af* rftmtions and dassificaUons are intended to be prac- 



cientifically rigid. 



A. DKF1M 



S A DIRECT ; s a unidirectional cur: 



I A r is a steady, or non-imitating, direct current. 



; nt to the superpov 



alternating current upon a continuous current. 



An ALTERNATING Ct RRENT OR E.M.F. it a currerr 



when plotted .IK' m rectangular coordinates, consists of half- 



waves of equal area in successively opposit- us from the tero 



a CYCLE. Two imn. ucceeding half-waves constitute a cycle. 



6b Pi KI- ired forth n of a cycle is called a penod 



REQUENI cycles per second is called the frequency 



M WAVK-FOEM. Theshajv fe.mf. or current plotted against 



time in rectangular coordinates, is ordinarily referred to as the wave-form or 

 wave-shape. Two alternating quantities are said to nave the same wave- 

 shape if their corresponding phase ordinates bear a constant ratio. The 

 wa\ .is ordinarily understood, is thus independent of the scales to 



which th 



Se SIMTLB A i Unless otherwise specified an alternating 



current or e.m.f. is assumed to be sinusoidal, ana the wave a sinusoid, 

 sine-wave or curve of sines. On this account a complete c 

 860 degrees, and any j>< ay be expressed in degrees 



, such as the ascending tero-p* 

 is a non- sinusoidal wave 



complex -\f> wave is capable of being resolved into a single 



f fundamental f: with superposed odd-frequency 



waves, or ripples. Of I . (2 + !) times the 



fundatiK v. each harmonic having constant amplitude 



a definite st on to the fundamental sine-wu 



custom.. inolvzing a complex wave, to neglect harmonics higher 



tha <her than 11 times the fundamental. 



i>ecial cases, h itill higher may have to be considered. 



In cert : cases cvep harm 



6g Rooi K VALUE (sometimes called the Virtual or Efl 



Val ss otherwise specified, the rating of an alternating-current or 



e.m.f.. in amf>eres or volts, is assumed to be the square root of the mean 

 square value taken throughout one or more complete cycles. T 

 sometimes abbreviated to r.m.s. The term root-mean-square it to be 

 rrt-d to the terms virtual or effective. The root -mean -square value 

 is indicated \ ;>erlv calibrated Alternating-current voltmeters and 



am: c of a sine-wave, the ratio of the maximum to the 



r.m.s. value is \ X 2. 



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