I am designing a single phase power measurement circuit using the ADE7763 for interfacing to a controller circuit. I need to achieve 3750V reinforced insulation between ADE7763 power measurement circuit and ucontroller. Rather than achieving insulation on the digital side of the ADE7763, I was wondering if it is feasible to achieve it on the analog side. For current measurement, this can be achieved using a suitably rated current transformer. However, for the voltage measurement, I would need to use a pair of say 490k resistors from each of the Phase and Neutral lines (refer circuit sketch). Since the voltage measuring input of the ADE7763 is now subject to common mode voltage between ground and neutral, I am wondering what the common mode rejection performance of the ADE7763 input stage is, however no such information is provided in the ADE7763 datasheet? Does this mean that I should not be making voltage measurements this way? Any advice on this matter would be greatly appreciated.
Even if you decide to use just the resistor divider( as you have it in the schematic) without any isolation, it would still work. Just make sure that the common-mode voltage isn't large enough. We do not have a specification for it, but in reality, if it is less than 75mV for ADE7763, there should be no problem.
If you need to isolate between the analog ground and your digital ground, a voltage divider is NEVER enough. If you want to isolate in the analog side you could use isolation amplifiers, but my experience is that it is way easier to isolate on the digital parte, using an SPI isolator.
I mean digital ground of uController (not of ADE), which is what is being asked
if you want to realize an isolated voltage measurement system you need isolation block between the metering circuit and microcontroller (a voltage divider is not sufficient). If you don't want to consider digital isolation, please have a look at ADE7912/3 or ADE7932/3.