Analog circuitry before ADC for mains voltage signal

[electronic_engineer]

Hi,

I am interested in seeing the frequency response of power line communication (PLC) signal (50 KHz) injected into the mains voltage i.e 220 volts. I need to have some kind of analog circuitry to down convert 220 volts to low level before using analog to digital converter. At what voltage range I should down convert my signal in order to get good dynamic range of ADC ?

One more thing I would like to ask, will down conversion affect the PLC signal which is 50 Khz in my case ?

Thanks.

 

[electronic_engineer]

Hey guys,

Please respond to my question

 

[rampat]

It depends upon your adc power supply,reference voltage and dynamic range ...

-Rampat

 

[mikersia]

First of all please see datasheets and application notes of ICs designated for power measuring. Such IC have a number companies, like Analog Devices, Microchip, Texas Instruments, ... This documents describe circuit around mains as well. Main difference of it's A/D conversion with your task is frequency range of interest, - i.e. up to 1KHz for power measuring instead of 50KHz in your case.
Typically a high ohmic resistive devider is used to apply main voltage to ADC input, and scale factor is adjusted to IC's requirements. Such devider together with antialiasing LP filter gives significant phase error above 1KHz bandwidth. So your task is to chose parameters of this input circuit, suitable to 50KHz bandwidth and accuracy requiments.