The increase of the index of network equations due to fault injection

This paper demonstrates the possibility of occurring numerical problems in analogue fault simulation due to a fault-injection-caused increase of the DAE-index. Based on analytical results and fault simulation experiments with two electrical networks it is described that a network showing no numerical problems during its fault-free simulations may increase its index as a result of the injection of a fault. The higher index causes numerical problems during the simulation. Some suggestions to tackle such index problems will be discussed.