TRANSIENT RESIDUAL VOLTAGE ANALYSIS DURING ISOLATED OPERATION OF A GROUP OF INDUCTION-MOTOR LOADS

The bus transfer schemes are provided in emergency switchgears feeding critical duty auxilary loads in process plants and thermal/nuclear po wer plants. During the time of bus transfer, group of such loads gets isolated from power supply. Transient residual voltage analysis of suc h loads, mainly consisting of induction motors loads, plays a vital ro le in deciding the transfer scheme. This paper reviews some of the exi sting machine models and solution techniques suggested for predicting the voltage transients during isolated operation of induction motors a nd reports a new solution algorithm based on a non iterative scheme fo r the multimachine case. The new solution scheme is found to be more r eliable and faster than the existing scheme. The theoretical results u sing various models have been compared for single as well as multimach ine cases. The practical validity of various models have been studied by comparing the theoretical results with actual test results obtained in laboratory.