1.Dissolved Gas Analysis (DGA): Faults due to arcing, high current breakdown of oil, localized sparking, partial
discharge of oil, localized overheating or hot spots, etc. causes thermal degradation of oil and used for analysis.
2.Thermography of Transformer: Hot Spots on the transformer bushing, circulation of oil in radiator tubes,
distribution of heat on transformer body, etc.
3.Capacitance Tan Delta: to detect oil degradation.
4.Oil Sample Test: to check the oil quality.
How Transformer Protection provided for external faults? Answer:
1.Differential Protection
2.Restriced EarthFault Protection
3.Over Current Protection
4.Over Fluxing Protection
5.Over current relays with under voltage blocking
6.Zero sequence protection.
7.Negative phase sequence protection