What is a Kelvin Connection?
A Kelvin connection is a means of making electrical potential contact with a current carrying component in such a way that eliminates or greatly reduces the effect of contact resistance. This is especially important when dealing with low millivolt reference voltages with relatively heavy loads where contact resistance is a significant and unknown variable. The best means is to use a (4) terminal device in which two terminals conduct the high current, while the other two are used expressly for sensing and correcting for error voltage. When working with two terminal devices, clip leads are sometimes connected as close as possible to the reference element to compensate for voltage error induced in test leads — these are referred to as Kelvin Clips. In this case, clip leads are used for making temporary measurements, but a two lead device may be converted to a (4) lead device simply by replacing the clips with soldered leads.