Software model for inverse time overcurrent relays incorporating IEC and IEEE standard curves

This paper describes a software model for the time domain simulation of inverse time overcurrent relays. The software model incorporates the IEC and IEEE standard curves, and was developed using Fortran language under the PSCAD platform. The software model simulates the effect of current on an inverse time overcurrent relay, and can be configured to represent various custom-designed overcurrent relays. Extensive tests have shown that the software model can be used to simulate electromechanical, static analog and digital time overcurrent relays with accuracy.