Substations use power transformers with ratings matched to forecast peak loads, impedance levels for fault control, and cooling classes such as ONAN/ONAF/ODAF to dissipate thermal stress. Bus arrangements (single bus, double bus, breaker-and-a-half) provide flexibility for switching and reliability. Tap changers regulate voltage under load, and protection schemes such as differential, overcurrent, and Buchholz relays ensure fast isolation during faults. SCADA and digital monitoring track hot-spot temperatures, dissolved gases, and load profiles to keep the transformer within thermal and insulation limits during heavy duty cycles.