Electrical Bearing Damage, A Problem in the Nano- and Macro-Range

Abstract

Rolling bearings face different damaging effects: Besides mechanical effects, current-induced bearing damage occurs in electrical drive systems. Therefore, it is of increasing interest to understand the differences leading to known electrical damage patterns. It is of utmost importance not to consider the harmful current passage in the machine element as an isolated phenomenon but to take into account the whole drive system consisting of the machine elements, the electric motor and the connected power electronics. This publication works toward providing an overview of the state-of-the-art of research regarding electrical bearing currents.

A Review on Sensor‐Integrating Machine Elements

“…[225] An indispensable requirement for the idea of a sensory utilizable rolling element bearing is the understanding and modeling of all relevant influencing factors on the electrical properties. [230] In the late 1950s, the capacitive model served as the base to measure the lubrication film thicknesses of rolling contacts in order to develop formulas that allow a reliable prediction of rolling bearing's lubrication condition, see for example, Lewicki [231] and Crook. [232] Capacitive lubrication film thickness measurements are since then utilized for the analysis of steel on steel contacts in the EHD regime.…”

Analyzing Ball Bearing Capacitance Using Single Steel Ball Bearings

“…First, in inverter fed electrical machines, the bearing's capacitance has an influence on the resulting voltage drop over the bearing. Hence, a better prediction of the capacitance helps to estimate and reduce the risk of damaging bearing currents [1][2][3][4][5]. Secondly, eligible bearing capacitance models allow the utilization of rolling element bearings as sensors, as the capacitance depends on the bearing load [6,7] and the lubrication condition [8].…”

Influence of the Shielding Winding on the Bearing Voltage in a Permanent Magnet Synchronous Machine

“…The current flowing through the bearing often causes local heating of the bearing, even to the melting point. In places where the metal has been melted, traces of discoloration or pitting of various shapes and sizes are formed [7]. The further flow of bearing currents in the presence of precipitated metal filings results in a deepening of the bearing damage process.…”

“…The intensity of the damage largely depends on the intensity of the current, the time of its flow, the rotational speed, the mechanical load and the type of lubricant used [8]. The available publications provide comprehensive information on bearing failures by categorizing the causes of their occurrence and present photographs of the consequences of bearing current flow [7,[9][10][11]. Bearing current density Jb is defined as the ratio of the bearing current amplitude Ib(peak) to the Hertzian contact area AHz (1):…”

“…This asymmetry may be caused by, among other things, the asymmetry of the air gap (static or dynamic), damage to the magnets placed in the rotor, the asymmetrical connection of windings, the short-circuit of the stator sheets, the anisotropy of the magnetic circuit or the segmentation of the stator core, which occurs in large-sized electrical machines. Another reason for the formation of magnetic circuit asymmetry may The available publications provide comprehensive information on bearing failures by categorizing the causes of their occurrence and present photographs of the consequences of bearing current flow [7,[9][10][11]. Bearing current density J b is defined as the ratio of the bearing current amplitude I b(peak) to the Hertzian contact area A Hz (1):…”