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%
Summary of Contents for PD-185
Page 1: ...MULT METRO DIGITAL DIGITAL MULTIMETER PD 185 0 MI1426...
Page 4: ...MANUAL DE INSTRUCCIONES PD 185...
Page 28: ...MANUAL DE INSTRUCCIONES PD 185 P gina 24 11 2015...
Page 32: ...USER S MANUAL PD 185...
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