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AC voltage measurement

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Maverickmax

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Hi

I have been asked to measure the AC voltage in term of RMS which I am unfamiliar with. Can anyone please kinldy point out how to measure the RMS voltage.

MaverickMax
 

metal

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Hi

You can rectify the AC voltage, use a voltage divider, and multiply the resulting value by 0.707 to achieve the RMS value.
 

Maverickmax

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My supervisor asked me to get RMS voltage for a short period of time which is summat Im totally unfamiliar with.

Any suggestion?

Is there any kind of formula for me to implement RMS voltage over a period of time?

Maverick Max
 

silvio

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Start reading in this order:

http://www.broadcast.net/hallikainen/theory11.html
a clearly explanation of what "arithmetic mean" means, how we calculate the power, why we use the average and how all this thing are related with your requested "short period of time"

Then read this one if you have more doubts:
http://www.bcae1.com/voltages.htm
where you can find how a 'true RMS' voltmeter calculates the voltage. The example will bring you closer to the requested "short period of time"
In the same time you can find why if the waveform isn't a pure sine wave (like a square wave or a signal with mixed sine waves of different frequencies or music), multiplying the peak times .707 will not give an accurate RMS value and therefore will not give an accurate indication of the work that the waveform can produce when driving a load.


Finnaly read this one
http://www.ee.unb.ca/tervo/ee2791/vrms.htm
where you can find why none of the answers on the top of the page are not correct.

Just for fun.
One method of measuring true RMS voltage is to measure the heat generated when the signal passes through a resistor.
How you can do that for "short period of time" ?
 

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