The reliability of various machinery is a perennial concern at the forefront of scientific inquiry. In the study of electrical machines and drive systems, one of the vulnerable components is identified as bearings. While bearings are intricate mechanical elements designed to withstand substantial loads, they are not equipped to handle electrical currents. If currents pass through them, it can lead to degradation of the bearing components and early failure, ultimately resulting in the breakdown of the entire drive system. Due to several factors, parasitic currents frequently traverse the ball bearings in modern machines, compromising their reliability and causing unexpected failures.

In the PROTOR project, we are investigating a novel countermeasure to suppress bearing currents, with the goal of preparing it for commercialization. Stray currents are powered by the parasitic capacitances of electric machines, and eliminating these capacitances resolves the issue of bearing currents. This can be achieved through the use of special slot wedges, wherein integrated grounded wires act as electrostatic shields, breaking up undesired capacitive couplings. In addition, this project develops analysis and monitoring tools to address the problem of bearing currents.

This project is funded by Business Finland and implemented in cooperation between LUT University and LAB University of Applied Sciences.


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Project funding:
Business Finland

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The objective of the project is to prepare for commercialization the technology of special slot wedges for electrical machines as a countermeasure against bearing currents, being invented and developed at LUT University. The final deliverables are

  1. Technical research:
  • preparation and testing of proof of concept
  • manufacturing of slot wedges samples
  • development and testing of software tool capable of analyzing the treat of bearing currents in a certain machine.

2. Market research:

  • identification of sectors with most suitable potential customers
  • analysis of business models to enter the market
  • building a network with potential investors


Reduction of non-circulating bearing currents by electrical machine design | 2023

Publication type: Doctoral disertation

Author(s): Vostrov, Konstantin

Contact information

Other staff

Outi-Maaria Palo-oja

LAB Project Manager

Anu Kurvinen

Business champion

Joni Surakka

RDI specialist

Sofia Ramos Velasquez

RDI specialist