4 Wire Compensation

Four wire compensation mode is designed to allow accurate measurement of voltage at the device under test by sensing around voltage loss in the lead cables. This is important as current levels increase since the current flow increases the voltage drop across a cable. For instance, if the lead resistance is 0.1 Ohms it may be fine for standard voltage measurements with a DMM, but if you are supplying 10 amps through that wire, there is a 1 volt voltage drop across that wire. Use the sense lines on the SPD1000X, SPD4000X, SPD5000X, or SPD6000X models. On the linear supplies (SPD1000X and SPD4000X) activate the sense mode from the front panel after connecting the sense wires as close to the DUT as possible. On the switching supplies (SPD5000X and SPD6000X) the sense connectors are by default in use, but are connected to the output stage on the rear of the instrument. Remove the bridge and connect the sense lines to where the power meets the device. Do not operate the instrument without the sense lines correctly connected to the supply or the circuit.

The SPD1000X can compensate for up to 1 volt of difference. The SPD4000 can compensate for up to 0.6 volts of difference. The SPD5000X and SPD6000X are both specified for remote compensation voltage of up to 0.6 volts on a single wire.

This capability is also standard on digital multimeters for voltage and resistance measurements.