1) A three-phase 250 kVA transformer, 13 kV: 480 volts operating at 60 Hz is connected to the primary side with a line impedance zline = 0.3 + J1.6 per phase which in turn is connected to a source. The coils on both sides of the transformer are connected in Y. In the secondary winding there is a load connected in Y and is operating with nominal current (Irated) with a power factor of 0.8 lagging. Assume as reference voltage line to neutral at the load.
a. Draw the equivalent single phase circuit with the data provided.
b. Find one of the line currents on the primary side and its angle.
c. Find one of the source voltages ( line to line values and per phase)
d. Determine the total complex power supplied by the source
2)A power system is comprised of a three-phase generator of 13kV, a step down transformer with turns ratio 6.25: 2 and 6MVA capacity, a three phase line 0.2 + J1.5 per phase and balanced three-phase load connected in delta 3 + j9 operating at nominal voltage. The coils on both sides of the transformer are connected in Y. Use as reference voltage between phases A and B in the load and use as base the load voltage and as power base use 6MVA.
a. Find the base voltage, current, impedance and power values in all areas of the system.
b. Convert to a per unit circuit and draw a circuit were you identify clearly the source, line, and load.
c. Working on per unit determine the phase voltages on the load, phase currents on the load and the line currents.
a. Draw the equivalent single phase circuit with the data provided.
b. Find one of the line currents on the primary side and its angle.
c. Find one of the source voltages ( line to line values and per phase)
d. Determine the total complex power supplied by the source
2)A power system is comprised of a three-phase generator of 13kV, a step down transformer with turns ratio 6.25: 2 and 6MVA capacity, a three phase line 0.2 + J1.5 per phase and balanced three-phase load connected in delta 3 + j9 operating at nominal voltage. The coils on both sides of the transformer are connected in Y. Use as reference voltage between phases A and B in the load and use as base the load voltage and as power base use 6MVA.
a. Find the base voltage, current, impedance and power values in all areas of the system.
b. Convert to a per unit circuit and draw a circuit were you identify clearly the source, line, and load.
c. Working on per unit determine the phase voltages on the load, phase currents on the load and the line currents.
