Field Reliability Analysis of DC Traction Motors for Electric Railcars

This paper presents field reliability analysis to estimate the failure rate and remaining life of old DC traction motors for electric railcars. The analysis includes life data collection, distribution analysis to select a life distribution to use for modeling the life data, and estimation of the failure rate and remaining life. The life data are collected from field maintenance records, which consist of the time-to-end data of rotors and stators ranging in age from 18 to 30 years. A distribution analysis makes it clear that three-parameter Weibull distributions fit the life data, and Weibull shape parameters are greater than 1.0, showing an increasing failure rate caused by wear with age. The remaining life of the units reaching a specific age is estimated by the remaining life distributions, which are derived in the form of a conditional three-parameter Weibull distribution. Calculation methods are provided for reliability criteria to evaluate the remaining life: the failure rate, the expected remaining life, and the chance of failure before the next overhaul Copyright (C) 2008 Praise Worthy Prize S.r.l - All rights reserved.