Influence of electric discharges on bearings of electric machines

摘要

I the last time many articles were found out discussed about shaft voltage, bearing currents and theirinfluence on lifetime and reliability of electric machines bearings. This is associated with extension of use ofstatic converters for control drives for DC motors feeding in the past and for induction motors feeding fromfrequency converters in the last time. It is known from our own experiences that not all failures assigned tobearing currents were their real reason and we also know how hardly the mentioned currents can be measured onreal machines and how work-intensive and expensive is to detect real reason of the failure on damaged bearing.We will not concern with basics of classical bearing currents in this paper, because they were known and studiedin the beginning of the last century but our own investigations will be presented.