Table of Contents
Advertisement
(2)
Root-Mean-Square and Peak Value Calculations
Y o u r V T - 1 7 1 F V T - 1 7 1 E J , an voltmeter of absolute-mean
value indication type, reads root-mean-square values of
sinusoidal wave inputs. A l s o , it deflects the pointer in
proportion to the absolute-mean value of a given input
wave.
If the f o r m f a c t o r ( = root-mean-square v a l u e / a b s o l u t e
mean value) of the input wave and the crest ( = peak
value/root-mean-square v a l u e ) are known, then the
root-mean-square value and peak value can be cal-
culated as f o l l o w s .
a . Assume t h a t the meter reads V .
•
Absolute mean v a l u e = •
•
Root-mean-square v a l u e = ( A b s o l u t e mean v a l u e )
x ( f o r m f a c t o r ) .
•
Peak v a l u e = (Root-mean-square value) x ( c r e s t ) .
b. F o r rectangular waves, their f o r m f a c t o r is unity
(1) and the crest u n i t ( 1 ) .
•
Absolute mean v a l u e =
•
Peak v a l u e = 0 . 9 V .
2\Tl
V ^ 0.9 V .
TZ
/
2v
~2~
- V ^ 0 . 9 V .
7C
c.
F o r sawtooth waves, their f o r m f a c t o r is 2 / v
the crest \ / 3 " .
•
Absolute mean value =
•
Root-mean-square value =
x - = V =
- - ^ - V ^
•
Peak v a l u e = -
^
3
7TV
/
3
_
and
V ^ 0.9 V .
7T
1.04V.
x
^
— 1 . 8 V .
%
Advertisement
Table of Contents
