ABSTRACT This paper describes a method for security control, i.e.,line overload alleviation using line switching under a line outage condition. The assessment Is made In a preracontlngency case using the line outage distribution factors. A simple and efficient method has been developed for quickly assessing the line flows after the contingency and swltched-out line. This quick assessment has been used to develop an Interactive algorithm for searching a suitable line candidate for switching so as to alleviate line overload or rotation of It from one set of lines to others. The effectiveness of the algorithm Is demonstrated on two sample test systems.