Question

1. The one-line diagram of a three-pha  se power system is shown in Figure 3.29. Select a common base of 100 MVA and 15 kV on the motor side. Draw an impedance diagram with all impedances including the load impedance marked in per-unit. The manufacturer's data for each device is given as follow:

The three-phase load at bus 4 absorbs 57 MVA, 0.6 power factor lagging at 10.45 kV. Line 1 and line 2 have reactances of 48.4 Ω and 65.43 Ω it, respectively.

2. The motor on the question 1 operates at full-load 0.8 power factor leading at a terminal voltage of 10.45 kV.

(a) Determine the voltage at the generator bus bar (bus 1).

(b) Determine the generator and the motor internal emfs.

3. The one-line diagram of a power system is shown below

The three-phase power and line-line ratings are given below.

Obtain the T-circuit equivalent impedances of the three-winding transformer to the common MVA base. Draw an impedance diagram showing all impedances in per unit on a 100-MVA base. Choose 22 kV as the voltage base for generator.

5. The three-phase power and line-line ratings of the electric power system shown in Figure given below.

(a) Draw an impedance diagram showing all impedances in per unit on a 100-MVA base. Choose 20 kV as the voltage base for generator.

(b) The motor is drawing 45 MVA, 0.80 power factor lagging at a line-to-line terminal voltage of 18 kV. Determine the terminal voltage and the internal emf of the generator in per unit and in kV.

6. The one-line diagram of a three-phase power system is as shown in Figure below.

7. The one-line diagram of a three-phase power system is as shown in Figure below. The transformer reactance is 20 percent on a base of 100-MVA, 23/115-kV and the line impedance is     MVar