Practical model of the axial magnetic field in the end region of large turbo-generators

Abstract

Purpose

The axial magnetic field occurs in the end-region of large turbo-generators is known to induce hot points or voltages between laminations, that may cause insulation breakdown and thus stator faults.

Design/methodology/approach

It is important to dispose of simple methods for estimating the axial flux rapidly with regard to the operating point of the machine.

Findings

The authors provide a practical model of the axial magnetic field based on a simplified vector diagram. The parameters required to build the vector composition of the flux densities are assessed with a limited number of finite element method simulations of the whole end-region of the machine. These simulations were validated by an experimental test on a real turbo-generator. Then the axial flux density was simply estimated for various operating points.

Originality/value

The originality of the paper concerns the practical model of the axial magnetic field based on a simplified vector diagram.

Citation

Demian, C., Romary, R., Vogt, G. and Costan, V. (2019), "Practical model of the axial magnetic field in the end region of large turbo-generators", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 38 No. 4, pp. 1295-1305. https://doi.org/10.1108/COMPEL-10-2018-0435