In the circuit shown in Figure 1 V 4kV X 2 ohm R 1 ohm an

In the circuit shown in Figure 1, V = 4kV, X = 2 ohm, R = 1 ohm and omega = 2 pi 60 rad/s. Determine the following: The rms symmetrical fault current. The rms asymmetrical fault current at the instant the switch closes.

Solution

RMS symmetrical fault current can be defined as the maximum number of cycles that are left after the short circuit has been initiated.

Symmetrical Current(Isym) = M x Isc

M=1/1+f

f=60Hz

M=.016

where M is the multiplier factor.

Therefore Isym=0.016 x 1.3

=.00208A