RELIABILITY EVALUATION AND OPTIMIZATION OF THYRISTOR DRIVE SYSTEM

Abstract

With the progress in automation, there is a growing demand for reliable stepless variable speed drives which have the ability to respond quickly and accurately to external speed and torque demands. As a result of recent advances in solid state technology and with the availability of high power reliable and efficient thyristor convertors; the use of thyristors to control large amount of power is being made. Due to the complexity of control circuits and inability of electronic components to perform consistently, reliability of SCR controlled drives has been found to be very poor. , ,~~ Generally, the SCR controlled drive systems are maintained systems in which the failed equipment is repaired and installed or is replaced by a spare. For such systems, the reliability function alone does not give the correct - picture of systems performance. This dissertation brin s ,out the availability of drive systems by introducing repair rate, installation rate and spares. The calculation of the steady state availability has been done by a symbolic method. Since all the maintenance facilities are connected with cost,the total cost of the system increases by provid-ing these facilities. The optimization has been done for repair rate and number of spares for achieving the desired level of availability at minimum cost.