• The single-phase circuit of Fig. 6.5.



  • Where Vs = 240 V (rms), and the system frequency is 50 Hz, R = 0.864 Ω, L = 11 mH ( ωL = 3.46 Ω ) and the load is R-L comprising of an 8.64 W resistor and a 49.5 mH inductor ( ωL = 15.55Ω ).



  • When the system operating in the steady state, the switch S is suddenly closed creating a short circuit.
  • The current (i ) waveform is shown in Fig. 6.6. The current phasor before the short circuit occurs is

A
This means that the pre-fault current has a peak value of 15.97 A.