Electromagnetic Field and Partial Discharge Division performs measurements of partial discharge (wnz) with electric off-line method. This valuable form of diagnostics of the state of insulation finds application in the case of many diverse electrical power engineering devices. Its aim is to detect defects arising from technological and operational reasons poorly detectable with other methods, but significant for durability of the object The partial discharge is a local electrical discharge which takes place only in part of the electro-insulating system and doesn't cause direct loss of insulating properties by the object. However long-term occurrence of partial discharge often leads to such changes in the structure of insulation that cause the disruptive discharge (breakdown). Partial discharge occurs in structures of insulation systems of practically all high voltage electric equipment of the high voltage, that is for example: