RMS and Average Value of a Sine Wave and Calculation of Form fator

It deals with Calculation of form fator

1. U18EE105 – Basic Electrical Engineering
BEE- W9-L2-CDT-34
1
TOPIC : - Problems on R.M.S values, Average
values and Form factor of sine wave
Dr.D.Rakesh Chandra
Assistant Professor
Department of Electrical & Electronics Engineering
Kakatiya Institute of Technology and Science ,Warangal , India,TS
CLASSROOM DISCUSSION TOPIC

W9-L2-CDT-34

2. After completion of this lecture, students will be able to
solve problems on average and RMS values of a sine
wave
.
BEE- W9-L2-CDT-34 2
Lecture learning outcomes

3. RMS Value of Sine Wave
BEE- W9-L2-CDT-34
3
The RMS Value of an Alternating Current is that
when it compares to the Direct Current, then both
AC and DC current produce the same amount of
heat when flowing through the same circuit for a
specific time period.

4. Average Value of Sine Wave
BEE- W9-L2-CDT-34
4

5. Form Factor
BEE- W9-L2-CDT-34
5

6. Crest Factor
BEE- W9-L2-CDT-34
6

7. Problem-1
BEE- W9-L2-CDT-34
7
Find the rms value , average value and form factor
of a half rectified voltage .
The half rectified voltage is shown in figure,

8. Problem-1 Cont…
BEE- W9-L2-CDT-34
8

9. Problem-1 Cont…
BEE- W9-L2-CDT-34
9
The average value is given by

10. Problem-2
BEE- W9-L2-CDT-34
10
Compute the average and the effective values of the
square voltage wave form shown in fig.
Solution :
V= 20V :0< t < 0.1
= 0V : 0.1 <t < 0.3

11. Problem-2 Cont…
BEE- W9-L2-CDT-34
11
The time period is 0.3S.

12. Problem-3
BEE- W9-L2-CDT-34
12
Find the form factor and crest factor of the waveform
shown in figure.

13. Problem-3 Cont…
BEE- W9-L2-CDT-34
13

14. Problem-3 Cont…
BEE- W9-L2-CDT-34
14
Form Factor is ,
(rms value / average value)=14.43/12.5
= 1.154
Crest factor = (maximum value / rms value)
= 25/14.43
= 1.732.

15. BEE- W9-L2-CDT-34
15
REFLECTION SPOT-1
A sinusoidal alternating current of 6 amps is flowing
through a resistance of 40Ω. Calculate the average voltage
and the peak voltage of the supply.

16. Lecture Outcome Revisited
•After completion of this lecture, students will be able to
solve problems on average and RMS values of a sine
wave
BEE- W9-L2-CDT-34
16

17. Further Reading
•Textbook : K. Uma Rao, Basic Electrical
Engineering, New Delhi: Pearson Education,
2011
Reading:
Chapter4- Topic 4.12, 4.13 , 4.16
BEE- W9-L2-CDT-34
17