Using AD7280A to stacked voltage cell measurement in electrolyzer?

Hello,

Dear Friends,

I want to design a circuit to  measure individual cell voltage in electrolyzer system.

Electrolyzer consists of 170 stack cells (voltage of each cell: 1-5V, Total Voltage=850V).

Sampling time: 6KHz

True RMS of the voltages should be calculated in 20 msec.

I am going to design modular boards with two chained AD7280A ICs. I have some question about using AD7280A.

1. Can I use external isolated power supply for each AD7280A? and how they should  be?

2. Can I stack modules of two AD7280A with isolated power supply to measure all the stacked voltages of 850V system.

Any suggestions?

Regards,

HM