FIELD: electrical engineering; automatic emergency control of power systems. SUBSTANCE: device has phase angle increment detector, operating parameter check-up element, modulus shaper, comparator, and logic elements; in addition, detector is provided with two input frequency-to-voltage changers and output integrator. EFFECT: improved reliability of device; improved accuracy of phase angle increment calculations in operating interval of parameter check-up element; improved selectivity and reliability of automatic asynchronous-condition eliminating system. 2 cl, 2 dwg
