Experimental obtaining characteristics of current transformers for developing their models and determining the time of saturation of the magnetic circuit

Abstract

Electromagnetic current transformers (CT) are subject to saturation and residual magnetization of a magnetic circuit. This phenomenon has an impact on the operation of devices of commercial accounting of electric energy and relay protection and automatics (RPA). Saturation of the current transformer’s magnetic core can lead to emergency situations due to incorrect operation of the protections and excessive disconnection of the protected connections. At the moment, Russian norms do not regulate the work in transient modes, including short circuits with an aperiodic current component. The Ivanovo State Power Engineering University (ISPEU) conducts research on the topic of determining the time to saturation of CT at short circuit. The purpose of the work was to develop an algorithm for monitoring saturation and determining the time to saturation of the CT magnetic core, in order to ensure the correct operation of the RPA in all modes. The article is devoted to the method of construction and research of mathematical models of CT for calculating the time to saturation. The general structure of the algorithm for determining the time to saturation is presented.