Electrical feedthroughs are used to transfer electrical power through the wall of a vacuum system.   Electrical isolation is by means of a glass or ceramic seal between the conductor(s) and the flange / vacuum wall.   A wide variety of single or multi-way feedthroughs are available from high voltage / current for power transmission, to low voltage / current for electrical signals.   Liquid feedthroughs (e.g. water cooling) are also included in this category.