True Rms Measurements - Promax PD-185 Manual De Instrucciones

4.3 True rms measurements

This multimeter permits direct measurement of the true RMS value
of a signal. This is the best way to measure parameters used for
measurements relating to power.
The relationship between the total true RMS (AC+DC) and the
component AC and DC signals is given by the following expression:
True RMS = √ (AC RMS Component)
RMS is equivalent to that DC value which dissipates the same
amount of power in a resistor.
" Average-responding " meters provide accurate RMS readings for
sinusoidal signals, but can introduce significant errors when
measuring nonsinusoidal waveforms.
The following table shows the errors that result when the average-
responding measurement is used instead of the True RMS value.
Power Calculations (watts) from Voltage Measurements
Sine wave
Square wave
Triangle wave
Page 14
(VpK=100V, Load=1kΩ resistor)
AC RMS average
responding
5.0
12.3
3.1
USER'S MANUAL PD-185
2
+ (DC Component)
AC True RMS
5.0
10.0
3.1
2
Error
0%
+23%
-6%
11/2015