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Explanation of different current/voltage types: RMS, Peak, Mean, DC, AC

huynh213

Apr 12, 2016
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Hello,

As I use Digital Power Meter to capture current and voltage data out of my systems, I often see different types of current or voltage (Peak, Mean, DC, AC, RMS, RMN). Since I normally just use RMS or Peak for my calculation, I wonder if some of you can help me cover some other types so that I can have a better understanding of those.

I've been trying to Google a bit but couldn't find out any good sources that cover these material.
 

duke37

Jan 9, 2011
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DC Direct current, also used for voltage. This is where the voltage and current are constant and of only one polarity. The simplest to deal with.
AC Alternating voltage/current. This may apply to sine wave or any other wave shape where the current changes sine.
RMS Root Mean Square. This applies to AC and is the voltage/current that will give the same heating in a resistor as DC
Peak is the maximum voltage which is seen, it may be positive or negative.
Mean is the average of varying voltage/current.
RMN No idea.

Of you have an AC sine wave, then the peak is root 2 * RMS and the mean is RMS*0.9
Other wave forms may be vastly different.
 

davenn

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Sep 5, 2009
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DC Direct current, also used for voltage. This is where the voltage and current are constant and of only one polarity.

where the voltage is reasonably constant, the current can be varying continuously, it is still DC

AC Alternating voltage/current. This may apply to sine wave or any other wave shape where the current changes sine.

you may want to reword that a little as well ;)
 

duke37

Jan 9, 2011
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I looked up Wikipedia and they specify DC as one polarity and AC as repeatedly varying polarity.
I am used to circuits where the DC varies and can be considered a mixture of AC and DC.

Pehaps I shouldn't have tried to make a concise definition. Colin seems to think I do not know what I am talking about, maybe he is right.:)
 

dorke

Jun 20, 2015
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Welcome to EP.
Please explain what is RMN?
Where have you seen that?
 

davenn

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Sep 5, 2009
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I looked up Wikipedia and they specify DC as one polarity and AC as repeatedly varying polarity.

it was really to point out that for DC the voltage is reasonably stable, say from a battery/PSU but the current can be fluctuating considerably
say the varying load of a DC electric motor

I am used to circuits where the DC varies and can be considered a mixture of AC and DC.

A changing DC is OK as long as it isn't regularly cyclic in its variations .... it's just called varying DC
if it is regularly cyclic .. a pure or complex sinewave for example, then it is an AC signal

Perhaps I shouldn't have tried to make a concise definition. Colin seems to think I do not know what I am talking about, maybe he is right

making a clearer definition would have helped :)

And I wouldn't worry about what Colin says too much :rolleyes:
he gives us mod's enough to worry about ;)

your presence on Electronics Point is always appreciated, thankyou :)


Dave
 
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