NPI(D)800R ensures phase and earth overcurrent protection, in medium and high voltage electricity networks against short circuits of all types. This multifunction and directional (D) relay monitors faults between phases or between phase and earth, reverse currents, the thermal state of a piece of equipment, and also the proper functioning of the circuit breaker and its triggering circuit.

These functions associated with an R type modular unit, thus allow the NPI(D)800R to be used for quick replacement, by equivalence of function, of the relays of the CEE relays of the 700 and 7000 series (mechanical interchangeability)