The MRI4 is a feeder protection relay that provides precise and reliable protective functions and is very easy to operate. The MRI4 provides a number of three phase protection elements to safeguard against overcurrent, short-circuit and earth fault, all with inverse time (INV) and definite time (DEFT) tripping characteristics. The MRI4 is also ideal for the protection of isolated, resonant, resistive and solidly earthed neutral systems. It is designed to be used in both radial networks and single fed open ring main systems. It can also serve as backup protection for differential protection systems on generators, transformers, bus bars and electrical lines. For overhead line protection the MRI4 is also available with an optional auto reclosing function. The protection functions of the MRI4 have been adapted to comply with the requirements of the VDE‑AR‑N‑4110:2018. The MRI4 is available in 96 variants, that cover all combinations of properties that you might need or not need for your application. Each variant is uniquely specified by a typecode of form MRI4-2xxxxx (i.e. 5 digits/letters following the '-2'). Check the Order Form (depicted below, or in the brochure DOK-FLY-MRI4-2E or in the user manual MRI4-3.6-EN-MAN) for a complete overview.