Bus Type - Known Parameter - Unknown Parameter Load Bus -P, Q - V, phase angle Generator Bus - P, V (magnitude) - Q, Voltage phase angle Slack Bus Voltage - magnitude and phase angle - P, Q
The ratio of full load current to short circuit current = 1/6 Xsc = j/(1/6) External reactance required = j*((1/6) - 0.06)) = j*0.106 pu Full load current = (40*1000)/(√3*15) = 1539.6 A Per unit reactance = j*0.106 = (I*Xr)/V j*0.15 = (1539.6*Xb)/((15/√3)*1000)) = 0.60 ohm
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
Points should be consider for new transformer installation: Location Environmental impact Soils condition Survey of land Ventilation Grounding Wiring Fluid check Inspection
EXAMIANS