The top five essential tests for Transformers are crucial for assessing their condition and preventing unexpected failures. These include: Insulation Resistance (Megger) Testing, which measures the health of the transformer's insulation to detect degradation; Transformer Turns Ratio (TTR) Testing, which verifies the turns ratio and polarity to ensure the transformer operates as designed; Winding Resistance Testing, which helps identify loose connections, faulty taps, or broken strands in the windings; Dielectric Strength (BDV) Testing of Transformer Oil, which assesses the oil's ability to withstand electrical stress; and Dissolved Gas Analysis (DGA), a highly sensitive test that detects gases produced by faults, providing an early warning of internal issues. Collectively, these tests provide a comprehensive health check, enabling proactive maintenance and ensuring the transformer's long-term reliability and safety.