The name Kelvin describes the 4-wire technology used. This means that the test signal and the measurement signal (sensor line) are routed separately to the test object. Low-resistance measurements are only possible with this technology. This is a possible application of the high voltage Kelvin pins. The actual application is in high voltage testing. With this technology, the high voltage is passed through a pin and measured back from a second pin. Since the DUT himself short-circuits the test lead with the test lead, it can be 100% ensured that the high voltage is applied during the test.
Since all manufacturers of electrotechnical devices have to prove that the safety test has been carried out (and this is almost always the high-voltage test), there is no way around this Kelvin technology. A particular problem in high-voltage testing is when there are metallic screws in the test specimen made of plastic (such as with electrical tools). These screws can be live due to incorrect production and can therefore be dangerous. A high voltage test is absolutely inevitable. If the screw is not available, a good check is always displayed as the result. The high-voltage Kelvin pen can help here. This example with the screw can be applied to many other metallic components. Only if the high-voltage test is carried out can proof be provided in accordance with the applicable product liability law.