FIELD: power engineering. SUBSTANCE: emergency components of no-zero phase currents are measured, differential current of each pair is determined and divided by same current as that not included in this pair thereby determining three relative currents; modules of relative currents are compared with minimum and maximum setting currents and reactive components of relative currents are compared with intermediate setting current; if one of modules is below minimum setting current, single-phase fault is stated in phase not included in respective pair; if one module is higher than setting current, two-phase fault is stated in phases included in respective pair; if one of reactive components is between intermediate and maximum setting currents, it means that respective pair of phases is at ground fault. EFFECT: facilitated procedure. 3 cl, 9 dwg
