4-wire technique

The 4-wire technique or system (also 4-wire measurement or Kelvin measurement) is generally used in the measurement of electrical resistances to prevent that line and connection resistances falsify the measurement. In the 4-wire technique a known electric current flows through two of the four lines through the resistance. The voltage drop across the resistance is high impedance tapped on the other two lines and calculated with a voltmeter. The resistance to be measured therefrom is calculated according to Ohm’s law.

Another important area of application is in the hipot test. Here the 4-wire technique is applied to ensure that the high voltage is actually applied to the contacted points. To this end the high voltage is applied to the product to be tested via two contacts. Via two other, independent contacts which are applied to the same test points the applied voltage is now measured back. If no voltage is displayed here then there is no high voltage applied to the two points to be tested and the measurement must be interrupted. As there is often a lack of space for two independent connections per test point so-called Kelvin pins are used. These are contact pins which have two connections and two of each other independent insulated pins.

SPS electronic offers the 4-wire measurement technique both for the ground bond (PE) test and for the resistance test as well as for the hipot test. In our wide range of accessories you will find besides the corresponding Kelvin pins all you need for an easy operation.


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