Hi,
Converting high voltage AC to a digital value is a frequently asked question here. There are many discussions. Read through them.
There are some with simplified hardware and there are some with high hardware effort. Each of them has benefits and drawbacks and they are discussed.
Developing an electronics circuit starts with specifications: Values with units, tolerance, precision...
"500V AC" tells almost nothing.
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It could be 50Hz, it could be 50MHz. It could be almost pure sine, it could be a mixture of a whole range of frequencies.
It cold be the expected fundamental RMS voltage, it could be the expected measurement range Vpp of the transients.
"Will it capture harmonics"?
--> it depends on frequency (harmonics frequency and sample frequency)
It depends on harmonics voltage and ADC resolution
It depends on analog filters (anti aliasing filter)
It depends on calculation method
...additionally you should ask: does the used circuit suppress existing harmonics or generate additional harmonics....and does this start a new problem?
As so often: Our answers can only be as good as your question (given informations).
Klaus
Front ends for mains voltage measurement are a serial topic at Edaboard. Besides 500 VAC range and sufficient bandwidth for harmonics measurement, do you need true isolation or can you afford some Mohm common mode "leakage" resistance. If so, a differential voltage divider would an economic and accurate method.
For me, 500 VAC refers to 50/60 Hz fundamental (unless stated otherwise). Useful range for grid analysis is up to 40th or 50th harmonic, respectively you'll end up with >3000 Hz bandwidth. ADC sampling frequency > 7 kHz, depending on the anti-alias filter steepness.
A standard µC ADC can acquire the signal with well considered software design and adequate anti-aliasing filter. For a good dynamic range, you'll want >= 12 Bit ADC resolution, an oversampling sigma-delta ADC can ease analog filter design considerably.
Differential voltage divider (e.g. dual 5 Mohm:5kohm) + unity gain differential amplifier.
Forget about using a 6-bit ADC.
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