NPU800, NPU800R and NPU800RE will ensure the monitoring of the voltage phase and/or frequency of electricity networks. These multifunction relays monitor faults between phases or between phase and earth, the voltages, direct, inverse, homopolar (according to the wiring) and also the proper functioning of the circuit breaker and its triggering circuit. The minimum and maximum voltage and frequency thresholds destine these relays for simple monitoring operations of the network and the management of loads and load shedding.

These functions associated with an R type modular unit, thus allow the NPU800R and NPU800RE to be used for quick replacement, by equivalence of function, of the relays in the CEE relays of the series 700 and 7000 (mechanical interchangeability.