Benefits assessment of fault current limiters in a refinery power plant: a case study

Growth of industrial power plants and load increasing typically result in increased available short circuit currents that can easily exceed the interrupting capacity of the installed circuit breakers, whose capacity is also limited by aging. Complete replacement of the existing breakers, whose characteristics are no longer suitable to that application, may not be economical and can require customized breakers, as in the case of the actual industrial plant studied in this paper. After describing the refinery power system the results of accurate short circuit calculation in compliance with both IEC and ANSI/IEEE Standards are reported; considerations on selection of appropriate breakers for the analysed installation and issues of short circuit current limitation are highlighted; a cost effective solution in then proposed based on the use of CLiPs (current limiting protectors), along with criteria for the correct choice trigger level and peak let-thru values. Economical evaluation of the proposed solution supplement the work