Desconexiones frecuentes de planta de generación por protección de porcentaje diferencial

INTRODUCTION. This article discussed the incorrect operation of differential protections used in electric generators due to inrush of the power transformers. OBJECTIVE. Find an economical solution to the wrong operations of protections. METHOD. Using mathematical simulation including in this the result of testing the primary protections devices faced the problem. RESULTS. Changing some settings of the percentage differential functions solves the problem caused by incorrect selection of current transformers. DISCUSSION AND CONCLUSIONS. The differential percentage function has its most sensitive and vulnerable point to inrush currents in low current areas. Inrush current block function does not eliminate incorrect operation of differential protections on multi – generators schemes connected to a single bar. It is necessary to select current transformers with similar magnetic characteristic for use in generator differential protection.