Estimation of Residual Service Life Time Of Electric Machines Windings

Hesham Ahmed Mohamed Aly Habiba

Abstract

Reliability surveys performed by IEEE and EPRI on failures of large machines revealed that bearing failures are    40-50% of all failures, then the next major failures cause over 30% is attributed to stator windings. Unfortunately, most of windings failures cannot be discovered during routine tests, and it usually comes up as surprise during “normal operation.” Insulation aging and contamination are considered the major winding failures contributors. Winding insulation Aging is a natural slow degrading process occurs when operating in a certain conditions. Many studies and researches have been conducted to estimate residual service life of electrical machines windings as a part of equipments condition assessment and monitoring in the integral Predictive or Conditioned Base Maintenance System. Estimating service time enables maintenance staff to identify necessary measures to extend service lifetime, and controls equipment’s life cycle cost. This paper reviews insulation aging and failure mechanisms, correlation between different methods to condition assessment, and estimate service life of winding insulation, then recommends measures to maintain winding insulation in a good condition for the longest possible time.

Hesham Ahmed Mohamed Aly Habiba

Electrical & Cathodic Superintendent

Operations Sector – Sidi Kerir Terminal – Maintenance Department

Arab Petroleum Pipelines CO. – SUMED

431 El Geish Avenue, Louran

P.O.B. 158 El Saraya

Alexandria, EGYPT

Telephone: + 20 3 5749721, +20 3 5080089, +20 10 1606573         Fax: + 20 3 5080082