Promax PD-185, Инструкция по эксплуатации, Страница: 46 / 60

USER’S MANUAL PD-185
Page 14 11/2015
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)
2
+ (DC Component)
2
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
(VpK=100V, Load=1k
Ω
resistor)
AC RMS average
responding
AC True RMS Error
Sine wave 5.0 5.0 0%
Square wave 12.3 10.0 +23%
Triangle wave 3.1 3.1 -6%