Indepth Electrical engineering

  Differential Protection Relay (87T) – Brief Overview Purpose: Detects internal transformer faults (winding-to-winding, winding-to-earth, turn-to-turn). Provides fast and selective protection , minimizing damage and downtime. Working Principle: Based on Kirchhoff’s Current Law : Sum of currents entering and leaving the transformer winding = 0 under normal conditions. CTs on primary and secondary sides feed the relay. If sum ≠ 0 → Internal fault → Relay trips the breaker. Figure – Working Concept:     HV Side CT ---------\                         \                                   Differential Relay 87T ----> Trip CB  ...

  1. What Are No-Load Losses in Transformers? No-load losses (also called core losses ) occur in a transformer even when it is energized but not supplying any load . These losses are primarily due to: Hysteresis Loss : Caused by the constant reversal of magnetization in the transformer core as AC flows. Depends on the type of core material , flux density , and frequency . Formula: Eddy Current Loss : Caused by circulating currents induced in the core laminations. Reduced by using thin laminated sheets of silicon steel . Formula: Typical Values: Transformer Rating No-Load Loss (W) Approx % of Rated Power 100 kVA 400–800 W 0.4–0.8% 500 kVA 1.5–3 kW 0.3–0.6% 10 MVA 40–60 kW 0.4–0.6% Observation: No-load losses are re...

  Transformer Nameplate Details: A Complete Guide for Engineers and Operators The nameplate of a transformer is often referred to as the “identity card” of the equipment. It carries critical information about the transformer’s design, performance, and operational limits. For engineers, operators, and maintenance teams, understanding these details is essential for safe operation, correct installation, and effective troubleshooting. In my 20+ years of working with transformers—ranging from distribution units in urban substations to large power transformers in industrial plants—I’ve seen how misinterpretation of nameplate data can lead to costly errors, system inefficiencies, and even equipment failures. This article provides a detailed explanation of transformer nameplate details , along with their significance. 1. Manufacturer Details Name of Manufacturer : Identifies the maker of the transformer. Crucial for spare parts, warranty, and service support. Serial ...