Patent ID: 8598885

Claim:
A method for measuring differences in voltage drop, comprising: coupling a current measurement component having first and second terminals in series with a voltage source and a load device, the voltage source operating at a line frequency; providing first and second voltage drop circuits each comprising a fixed value component and an adjustable value component coupled in series; coupling the first voltage drop circuit to the first terminal of the current measurement component; coupling the second voltage drop circuit to the second terminal of the current measurement component; superimposing a relatively high-frequency signal onto a control input of the adjustable value components; adjusting the values of the adjustable value components based on any difference in voltage drop values produced by the first and second voltage drop circuits due to measured variations in the voltage drops produced by the high-frequency signal; and measuring the difference in voltage drop produced by the difference in voltage drop values produced by the first and second voltage drop circuits at the line frequency.