EnglishThree-phase Dry-type Transformer
Three-phase dry-type transformers (6–35 kV) are solid-insulation devices with epoxy-resin cast or encapsulated windings, containing no liquid coolant. Insulation systems meet Class F (155°C) or Class H (180°C) per IEC 60085. Cooling is achieved through natural (AN) or forced-air (AF) circulation. Voltage ratings cover 6 kV to 35 kV, with power capacities from 100 kVA to 12.5 MVA. Partial discharge levels are maintained below 10 pC at rated voltage per IEC 60270. Temperature rise limits are 100 K (Class F) and 125 K (Class H). Applications include indoor installations such as high-rise buildings, data centers, and underground substations where fire safety constraints apply. Routine maintenance involves cleaning cooling ducts and monitoring winding insulation resistance.
