Root Mean Square. Mathematical method to calculate effective value from an AC signal.
Questions tagged [rms]
226 questions
4
votes
2 answers
Why use RMS values instead of "mean of absolute"
Why do we use rms values? I can't get my head around why these values are used. I am doing an intro course to elec eng and we get given some values (normally voltages) in rms and others not, and we are expected to calculate other values but I don't…
sion
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RMS value of clipped sine
I'm confused about the Vrms value of a clipped rectified sine:
The reason it's clipped and distorted, is because it's the output from a tiny transformer (0.7W), and the filter bank charges at the peaks of the waveform, pulling down the…
Halfgaar
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3
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4 answers
RMS measurement/calculation On-the-fly
I have an SAR ADC to measure the RMS value of an AC signal. My present method is to use a timer to trigger the conversion and store the conversion result. When I've sampled a whole cycle of points, I subtract the DC level (the average of all points)…
diverger
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How can I calculate total RMS value from one pulse?
I tried to solve this myself, but I'm forced to beg for help.
I have a very short waveform, too short to resolve accurately on my scope. When I expand the waveform, the RMS of one complete pulse is 6.6 Vrms, 0.000 001 2 seconds long.
What would the…
William Mingin
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Is my average power logic correct?
Original question I am trying to solve:
This question is from "Fundamentals of Electric Circuits", 7th Edition from Sadiku and Alexander
For this question, capacitors don't have average power so the average power there would be 0. The resistor…
Otto367
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1 answer
Would analog multimeters measure correct dimmer's output?
Because I decided to regulate 230VAC with a dimmer (or SCR chopper), I want to measure the outcome (which is very big noise!) with a voltage and current meter.
I know I am supposed to take true RMS instrument, but would analog work too?
I don't find…
Jakey
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Is RMS value of a pulse wave practically useful?
As we know the mean value of a pulse wave (depending on its duty cycle) corresponds to a constant DC.
But when it comes to alternating current through a resistor for DC power correspondance we measure the RMS value i.e. RMS of an alternating current…
user16307
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Why is average power: the average of the voltage squared/resistance rather than the ((voltage average)^2)/resistance?
Regarding pulse waves specifically. So this should be especially simple.
I see it written that
$$\text{average power} = \text{average current} \times \text{average voltage}$$
which also equals
$$ \frac {\text{average voltage} \times\text{average…
ramose
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Trapezoidal wave RMS value
I am calculating RMS value of trapezoidal wave.
I found its formula like below:
and at last the RMS value formula:
u = 30degree or pi/6 --> especially pi/6
A = 12
When I calculate RMS value by this formula, I got 2 but by matlab, I got 11.314,…
Piko
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How can I find the RMS value of a wave in irregular form?
As a sine wave passes through a circuit, it clips and the waveform in the figure is formed.
How can I find the RMS value of a full wave?
Electronx
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Finding the RMS value
Here, I can't understand the third step. Why they ignored other three terms \$(40000\sin\omega t\sin 3\omega t, 10000\sin 3\omega t\sin 5\omega t, 20000\sin 5\omega t\sin\omega t)?\$ Please help.
Ankita Pal
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Why isn't RMS called SMR, when it's (linguistically) a square mean root?
This question falls into the funfact category, but I'm anticipating this question from my next course students and I'd like to have the answer, if there is any. In the spirit of English language, RMS is actually the waveform square mean root.…
Martin
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Calculating RMS of Simple Waveform
A problem in my textbook gives this task:
A solution is given as:
I tried to work this problem using a different method. I simply calculated the areas of the triangles as if the height of the triangles was A^2. This gives me this result:
I was…
elile
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AC Effect Value
"The effective value of an alternating current is that current which will produce the same heating effect as an equivalent direct current. The effective value is called root mean square RMS value."
What is that "heating effect" stated in the…
Kimley
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Do I have a true rms meter
I bought an Excel XL 830L multimeter with the understanding that it was a RMS voltmeter.
I also have UEI ElectroMate DM 200.
When I checked the output of my APC unit with both meters, the readings were about the same.
Is there a way to tell if a…
fixit7
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