Large AC Currents
Unlike other forms of current measurement the size of the sense coil (the Rogowski coil) is independent of the size of the measured current. Thus for large currents the size of the Rogowski coil can be chosen to suit the conductor diameter, whereas probes based on magnetic materials such as hall effect become increasingly bulky and expensive at larger current ratings.
Over a 1000A range there really is no better alternative to a PEM Rogowski current probe.