Voltage Measurement

The

RC high pass filter consisting of the high voltage capacitors and resistor divider network has a corner frequency of 4 Hz. Therefore, at 50/60 Hz the network divides the voltage by 805.

Current Measurement

Current measurement can be done with a Vitec 57P1832 current  transformer. This device contains a tape wound Silicon Steel toroid core that provides excellent  linearity at frequencies between 50 Hz and 120 Hz. The current transformer has 1000 turns and  will support up to 150 Amps before saturating.

In this application the primary winding is one turn, and the ballast resistor is 10 ohms. This gives a gain of 10 mV/Amp. By adding a MAX4173H, we can achieve 1V/Amp at the ADC.