ECE 5664 Lightning and Switching Surges
Assignment#2
RLC Transients
Submission Deadline: 03/01/2023
Name :S.No :-
Answer all the questions and upload the pdf/word copy of the solution on canvas by
11:59 PM 03/01/2023.
Question-1 (100 Points)
C1 = 60 μF, C2 = 60 μF and R = 5 Ω
The capacitor C1 in the figure has an initial charge of 1.0 Coulomb and C2 is
discharged. Calculate the following
(a) [10 Points] The peak current through the switch
(b) [10 Points] The current 200 microseconds after the switch closes
(c) [10 Points] The ultimate energy stored in C2
(d) [10 Points] The ultimate voltage on C1
(e) [10 Points] The total energy dissipated in the resistor
(f) [10 Points] Verify that energy is conserved
(g) [40 Points] Simulate the circuit in PSCAD-EMTDC and verify the above
results. Comment on your results.
Question-2 (80 Points)
Determine the following for the LC circuit shown below with the given conditions
C1 = 60 μF, C2 = 40 μF, QC1 = 1C, QC2 = 0C, X = 5 Ω
(a) [10 Points] Find the instantaneous current when the switch closes.
(b) [10 Points] Determine the peak current
(c) [10 Points] Find the energy stored in the inductor at t = 1ms
(d) [10 Points] Find the voltage across C1 at t = 1 ms
(e) [40 Points] Simulate the circuit in PSCAD-EMTDC and verify the above
results. Comment on your results.
Question-3 (80 Points)
The figure below shows the field coil of an electric machine. It is excited by closing
switch S1 onto an 800V d.c. bus.
(a) [20 Points] Determine the energy stored in the coil, and the energy dissipated
in the coil resistance, 1 sec after S1 is closed.
(b) [20 Points] When the coil current has attained a steady value, S1 is opened and
S2 is closed simultaneously. What will be the voltage across S1 0.1 sec later?
How much energy will eventually be dissipated in R2?
(c) [40 Points] Simulate the circuit in PSCAD-EMTDC and verify the above
results. Comment on your results.
R2 = 10 Ω, RF = 3.6 Ω and LF = 2H
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The system should be in steady state before opening S1
When simulating the circuit, S1 should be setup to interrupt the steady-state
load current
S2 needs to be commanded to close at the same time S1 opens.
Question-4 (80 Points)
A 230kV:69kV, 100 MVA three phase transformer (wye grounded-wye grounded) has
per unit leakage reactance of 10% with an X/R ratio of 15. This is supplied by a source
impedance of j0.05pu. No change of base calculations are needed.
(a) [30 Points] Calculate the worst case peak fault current for a fault at the low
voltage terminals. What is the angle of inception compared to the voltage
waveform (assume a cosine voltage source)? Include the resistance.
(b) [40 Points] Model the system referred to the low voltage winding for your
simulation in PSCAD-EMTDC, do not use the built-in transformer models yet.
(c) [10 Points] Using simulation only, repeat part A if the X/R ratio of the
transformer is 7.