Analyzing Ball Bearing Capacitance using Single Steel Ball Bearings - Data

Supplementary data to the publication "Analyzing Ball Bearing Capacitance using Single Steel Ball Bearings" by Steffen Puchtler, Julius van der Kuip and Eckhard Kirchner published in Tribology Letters by Springer. Capacitance measurements of hybrid ball bearings with a single steel rolling element were carried out. This helps to measure only one current path through the bearing at a time and thus, gives a much clearer picture of the contact capacitance of rolling elements in and out of the load zone. Provided is raw and evaluated measurement data as well as calculation results

The Influence of Load and Speed on the Initial Breakdown of Rolling Bearings Exposed to Electrical Currents

The reason for the failure of electric vehicle drives is increasingly current-induced damage to rolling bearings. Studies show that rolling bearings are more susceptible to current pass-through after the first occurrence of unwanted bearing currents. To investigate this effect, a test plan is introduced with variations in axial and radial loads, as well as rotational speeds. A new bearing is mechanically run-in for each test point and then subjected to a realistic voltage signal of gradually increasing amplitude. After the initial breakdown, the different voltage amplitudes are applied again to investigate the behavior after the initial breakdown. During the whole test, the maximum current, the duration and the dissipated energy of each breakdown are measured. The results provide insights into the processes after the initial breakdown and the stochastic nature of the breakdown behavior

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

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

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

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 comparison of an analytical and a numerical approach to calculate the electrical capacitance of rolling element bearings

The behavior of rolling element bearings in an electric circuit is of increasing importance over the last years. On one hand, the knowledge of electric properties is required for the evaluation of bearing damage due to inverter induced bearing currents in electric drives. Therefore, the bearing voltage ratio describes the ratio between the common mode voltage and the bearing voltage and is a function of the electric capacitance of the bearings inside the electric drive. On the other hand, the sensory utilization of the electric properties of the bearing shows a promising concept for condition monitoring and predictive maintenance purposes in various machine applications. By applying a non-harmful electric voltage to the bearing, it is possible to measure the electric impedance and calculate the load of the bearing via its electric capacitance. Though in both scenarios a precise modelling of the electric capacitance of the rolling element bearing is required, this work shows that the sensory utilization has higher demands on the description of the bearing capacitance. The scope is to compare two fundamentally different modelling approaches and examine their advantages and limitations. The first approach is an analytical approach based on analytic, semi-analytic and empirical equations and the other one is a Finite Volume Method (FVM) approach to calculate the rolling element-raceway contact within the fluid domain of the lubricant, the solid body domain of the rolling element as well as the thermodynamic and electric domain. To improve the comparability of both approaches, the pressure and temperature dependent modelling of the material properties are discussed. Furthermore, the comparison of the calculated values with experimental results allows an outlook for future improvements on each of the modelling approaches