MODERN NUMERICAL RELAYS IN PROTECTION OF POWER TRANSFORMER.

This article provides an overview of modern numerical relays used in the protection of power transformers. It discusses various protection schemes and their corresponding relays, highlighting the importance of proper protection for the safe and efficient operation of electrical power systems. The article covers differential protection, overcurrent and earth fault protection, standby earth fault protection, and restricted earth fault protection. It also addresses factors such as CT ratios matching, magnetizing inrush current, tap changer imbalance current, and zero sequence currents in designing effective protection schemes. The document further delves into the mathematical formulation and calculation of differential protection, as well as the use of high-impedance REF schemes and standby earth fault protection. It concludes by emphasizing the significance of efficient power system protection schemes in minimizing faults and ensuring stable power systems. [Extracted from the article]