3. Electrical wear and tear

3.1 Electrical connection

Electrical pitting is a type of spark plug electrode wear. It is a spark erosion process similar to that of EDM machining, caused by an electrical discharge across the interface. It results in the formation of surface cavities, significantly smaller than fatigue cavities, in the form of pits showing traces of metal melting, but without any noticeable cracking. This type of wear can affect plain bearings and the bearings of motors driving an electrical machine (alternator or dynamo) when the electrical insulation between the two components is not perfect and stray electrical currents are present. An example of electrical pitting observed on a diesel engine bearing of a power generation unit is shown on figure