Theory of Operation
The voltage sensor measures the voltage drop across a precision voltage divider, which is proportional to, but smaller than the voltage at the inputs. The current sensor measures the voltage drop across a precision 0.5 Ohm resistor, which is proportional to the voltage according to voltage = resistance * current. Current and voltage measurements alternate rapidly and multiple measurements are averaged in order to obtain an accurate measurement of real power.
The voltages are then digitized via a 12-bit Analog-to-Digital converter to obtain a PASPort-compatible signal.