Definition: The average value of an alternating current is defined as the D.C. current which transfers across any circuit the same charge as is transferred by that alternating current during the same time.
AVERAGE VALUE
Definition:
The
average value of an alternating current is defined as the D.C. current which
transfers across any circuit the same charge as is transferred by that
alternating current during the same time.
In
case of symmetrical wave forms, the average value taken over the complete cycle
is zero. In such case, only half cycle is considered for relating average value
with maximum value.
In
case of unsymmetrical wave forms, the average value must always be taken over
the whole cycle. Example of symmetrical wave forms is sinusoidal wave form.
Example
for unsymmetrical wave forms: Half wave rectified wave form.
Method
1 (Mid ordinate method)
This
method can be used for both sinusoidal and non-sinusoidal. It is more
convenient for non- sinusoidal waves. Refer the figure above.
Iav
= i1 + i2 + …. + in / n
As
is seen from the above expression, the accuracy of Iav depends upon the number
of terms. More the number of terms, greater the accuracy.
Method
2 (Analytical method)
We
must know the equation of wave form mathematically to find the average value by
analytical method.
i
= im sin θ
It
is a symmetrical wave form. To calculate the average value, only half cycle
must be considered.
For
a sinusoidally varying quantity, average value Voyant olma
Note
1.
In case of rectangular wave form. RM.S. value = average value. The reader is
advised to check this analytically.
2.
For all other types of wave forms. R.M.S. value is greater than the average
value.
3.
Moving coil meters indicate average values for the whole cycle.
4.
Moving iron meters always indicate R.M.S values.
5.
Hot wire ammeter indicates R.M.S. value of the whole cycle.
Electric Circuit Analysis: Unit I: b. Basic circuits analysis : Tag: : Definition, Formula | Basic circuits analysis - Average value
Electric Circuit Analysis
EE3251 2nd Semester 2021 Regulation | 2nd Semester EEE Dept 2021 Regulation