In an arc welder, arcing is the intended mode of operation and any protective devices are set accordingly. In the protection schemes used on the bulk electrica

In an arc welder, arcing is the intended mode of operation and any protective devices are set accordingly. In the protection schemes used on the bulk electrical system, we have very sensitive relaying that can pick up on faults of even milli-amps (remember at high voltage even a small amount of current can dissipate a lot of energy) to detect, for instance, high impedance ground faults or turn-to-turn faults inside a transformer.