Sensitivity improvement of time overcurrent relays

In this paper, we recommend a new adaptive function for time overcurrent relays. The purpose of the adaptation process is to improve the sensitivity of time overcurrent relays, which then operate with a dynamic pickup setting such as a load current. The results obtained from time overcurrent adaptive relays are collated, and the results from analysis of negative sequence relays and conventional time overcurrent relays are also presented. In this article, we describe the control logic structure of an adaptive pickup current and its performance under different operating states.