Magnetization and Primary Injection Test of Current Transformer for Protective Relaying

Emphasis is placed on the ability of current transformers to provide accurate operating current at normal system operation and other system disturbance to protective relay systems in high voltage power systems. This paper presents the results of a laboratory investigation of magnetization and primary injection test of current transformer; a basic requirement to ensure that a current transformer is in good condition and able to perform as it is designed to, before commissioned into service. The test carried out allows the magnetization curve to be deduced from the measured data. In addition, the current transformer was modelled by curve fitting the magnetization curve using MATLAB. The result obtained serves a guide for utility engineers who apply current transformers for protective relaying.