A complete excitation-shaft-bearing model to overcome the shaft induced voltage and bearing current

This paper proposes a complete distributed model for investigating the induced shaft voltage and bearing current in turbo generators due to the interaction with the static excitation systems. This undesirable voltage affects the insulations gradually, lowering the life expectancy of the whole system. If the shaft voltage exceeds the dielectric breakdown voltage level of the lubricating grease film in journal bearings, an electrical discharge current flows through the bearings. In order to inspect the shaft voltage, a passive filter is proposed to overcome the stated issue. Both the proposed model and the passive filtering technique are simulated with SIMULINK, and discussed in detail to confirm the presence of the bearing current and shaft voltage.