Shielding the end windings to reduce bearing currents

The problem of bearing currents as a parasitic phenomenon in electrical machines is a problematic issue in the modern industry. Although the origins and generation mechanisms of the phenomenon have been actively studied a general solution has not been given. The study presented here offers one countermeasure proposal. Not only the lamination stack area of the electrical machine is responsible for the building up of parasitic capacitances between different parts of the machine, but also the end-windings area has a significant contribution. The current paper introduces several designs of specific electrostatic shields, intended to cover the end-windings. The rate of capacitive coupling reduction was evaluated by FEM-analysis, and the effectiveness of differently designed shields was compared.