Calculate the base quantities and draw the per unit equivalent Now, consider a 1LG fault with impedance ZF= j0.001 p.u. located at the load bus on phase A. The sequence networks for this configuration are illustrated in Fig. 2 below (next page). 2. Calculate the fault current IF given the equivalent circuit in 2.

Assignment Task

1. Problems – Symmetrical Components and Fault Studies

2. Given the following unbalanced currents IABC , determine the symmetrical components current vector I 012 .

3. Given the circuit from Fig. 1, and the quantities S 3p = 30MVA and V LL = 12 KV,

And using the following parameters:
Generator

Line

Load

EG = 1.05∠0°p.u

S3p = 30MVA

VLL = 12 KV

XG= 0% (lossless)

Balanced, wye-configured, and solidly grounded

Xline = 3.6Ω

ZL = (70 + j18) Ω

Balanced, wye-configured, and solidly grounded

Answer the following questions:

1. Calculate the base quantities and draw the per unit equivalent

Now, consider a 1LG fault with impedance ZF= j0.001 p.u. located at the load bus on phase A. The sequence networks for this configuration are illustrated in Fig. 2 below (next page).

2. Calculate the fault current IF given the equivalent circuit in 2.

3. Determine the phase currents I AG, I BG , and I CG oming out of the generator during the

4. How do the currents coming out of the generator compare to the currents going into the load?

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