What is r.m.s. Value

Chapter 6.5 r.m.s. Value

Fundamental Electrical and Electronic Principles Third Edition Book
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Fundamental Electrical and Electronic Principles Third Edition Book

  • Alternating Quantities 205 (b) v5530045055424550893...... sin () volt sin ()a111nnd, V v49.Ans Note: Remember that the expression inside the brackets is an angle in RADIAN. (c) 35 53003003550 5455300... sin () voltso, sin ()sinttt1111 radand, ms 0 54550 57690 576930062006 24.....ttAAns A sketch graph illustrating these answers is shown in Fig. 6.6 . 4.5VavVm5.53.56.672.50.54.90t (ms)v (V) Fig. 6.6 6.5 r.m.s. Value The r.m.s. value of an alternating current is equivalent to that value of direct current, which when passed through an identical circuit, will dissipate exactly the same amount of power. The r.m.s. value of an a.c. thus provides a means of making a comparison between a.c. and d.c. systems. The term r.m.s. is an abbreviation of the square Root of the Means Squared. The technique for fi nding the r.m.s. value may be based on the same ways as were used to fi nd the average value. However, the r.m.s. value applies to the complete cycle of the waveform. For simplicity, we will again consider the use of the mid-ordinate rule technique.