Covered Conductor is extensively used in voltage up gradation projects ranging between 6.6KV to 33 KV. Covered Conductors are longitudinally water blocked and covered with special grades of materials that provide insulation and ultraviolet protection.
Here auto transformer change voltage from 600 V to 200 V. Voltage ratio (a) = 600/200 = 3 kVA rating of the auto-transformer = (a/(a - 1))*(kVA rating of auto transformer) = (3/2)*20 = 30 kVA
EXAMIANS