Impact of Throughput Impedance on Circuit Breaker TRV and RRRV

A quick simulation-based assessment to demonstrate the impact of Throughput Impedance on #TRV (transient recovery voltage generated across circuit breaker terminals).

In first scenario (Figure 1 below), the #CB interrupts three phase symmetrical fault current of around 17.5 kA X/R: 8, fed from a source which is connected electrically near (i.e., almost nil throughput impedance) to the CB terminals (i.e., onto the same bus to which the CB is connected).

In second scenario (Figure 2 below), the #CB interrupts same fault current (i.e., three phase symmetrical fault current of around 17.5 kA X/R: 8) but the fault current streams from Source to Fault Location through two OHL feeders.

So, it is evident from above simulation plots that when three-phase symmetrical fault current passes through some typical OHL feeder impedance (i.e., source to fault location throughput impedance), the TRV / RRRV becomes more severe than when there is no throughput impedance between source and fault location.