* Note - All questions should be answered with Laplace Transforms when possible.
Figure 3P.2 shows two capacitor banks, C1 and C2, in a substation. C1 is energized, but C2 is discharged. The three-phase, 60 Hz rating of the banks are: C1, 5 MVA; C2, 3 MVA, on a 13.8 kV base. The source has a short circuit rating of 20kA rms at 13.8 kV. The inductance of the loop between C1 and C2, represented by L2 is 30μH.
Calculate the peak transient voltage that will appear on C2 and the peak transient current that will flow in L1, if the switch S is closed at the peak of the voltage cycle. Point out any assumptions you make.
A line to ground fault occurs as indicated in Fig. 3P.4, close to the secondary terminals of a 230/34.5 kV transformer. The transformer has a three-phase rating of 100 MVA; it has 0.1 pu reactance on this base.
a.The fault current
b.The time to peak of the transient recovery voltage when the circuit breaker opens to interrupt the fault current. A value of 12.7nF can be assumed for the effective capacitance per phase of the transformer secondary winding.
C1=100μF; C2=40μF; L1=10mH; L2=20mH; C1 and L1 in Fig. 3P.8. are oscillating; C2 and L2 are de-energized. The switch is closed when V(C1 )=0 and I2=500A. Calculate: a.Peak voltage reached on C2 b.Peak current reached in L2 c.Frequency of the current in L1 d.Maximum voltage on C1 prior to closing the switch