Electric test probe 4P

The Kelvin test prod is used for Test prods two-pole contacting of connections or contacts which are difficult to reach, e.g. lamellae at the commutator of a motor, ground connections between components which are very close together or simply smooth surfaces where there is no other way of contacting. Using two Kelvin test prods, a 4- pole contacting can be realised where the contact and supply line resistances have no influence on the test result. Of course, you can also use the Kelvin test prod together with a Kelvin clipper or another two-pole connection to the measuring instrument, to obtain a 4-pole connection to the test object. The Kelvin test prod is of a robust design, a comfortable plastic handle supports the two coaxially arranged contact tips. The inner contact consists of a round material with a corresponding springmounted tip, the outer contact comprises a bevel-cut tube. The outer contact is used as the potential contact, the inner contact is used as the current contact. When a test surface is contacted, the spring-mounted inner current contact touches the surface before the external potential contact. When the test prod is removed, this process is reversed, so that the current contact is always the first and the last contact. This is important in the case of inductive test objects in order to avoid that the voltage input of the measuring instrument, which is always more sensitive, is exposed to inductive voltage surges when the test prod is disconnected. The connecting cable is screened, therefore there are three plugs or a three-pole plug (depending on customer’s specification) on the test instrument side, one of which connects the screen to ground.