RELIABILITY ANALYSIS OF SCR DRIVES

Abstract

With rapid developments in the technology of thyristors and solid-state devices, electric drives with solid-state control are becoming increasingly popular and are replacing all types of conventional drives. Since solid-state drives employ a large number of semiconductor and other electronic com- ponents, the study of reliability of these drives has become an urgent problem for Drive Engineers. This dissertation presets a detailed analysis of reliability characteristics of thyristor drives. Quantitative reliability is treated systema-tically and its application to SCR drives is particularly considered.. Logic diagrams for re-liability behaviour of equipment are developed and appropriate mathematical models are proposed. A mathematical model for a (m-1) -out-of-m redundant system with non-identical elements Is obtained and reported for the first time. The reliability of some important SCR drives is estimated and compared with that of the corres-ponding conventional drives. Redundancy as a means of improving reli:ability is discussed and the re-dundancy optimizz.;:ion of SCR drives is dealt with in detail. A cost comparison between optimal and non-optimal designs is also made. The effect of short-circuit failures on re-liability and cost of SCR converters is also briefly considered,..