FIELD: relay protection, automatics. SUBSTANCE: method is based on check of mutual power of three values: measured voltage, reference current and predicted voltage related to end of protected zone. Three pairs are formed from three values. In prototype only two of them are monitored which leads to loss of selectivity if injured phases are unknown in advance. Deficiency of prototype is corrected by determination of sign of mutual reactive power of two mentioned voltages and in proper cases of their mutual active power too. Adaptations of method differ by character of formation of comparable values and measures called for to enhanced its sensitivity and remove "blind zone" in case of close short-circuits. EFFECT: enhanced sensitivity of detection of injured phase and failure zone. 17 cl, 5 dwg
