Operation algorithm of two parallel lines protection that controls presence of current in their phases has been suggested. Its realizations on microprocessor and semiconducting element bases have been given. It is shown that protection is tuned away only from the unbalance current. Calculation of the value of its cascade action zone is formulated.

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Algorithms of operation of three or four parallel lines protections, based on the difference between the control currents in the corresponding phases and current in comparison with their idling current are proposed. The implementing of protections of three parallel lines on logic elements is given. The work is considered in different modes. It is shown that when the three lines of action of cascade zone do not exceed the line length of 0.08, while the four-0.06. Streszczenie. Opisano algorytm umożliwiający zabezpieczenie linii trzy-lub czteroprzewodowej bazujący na analizie różnic między prądami oraz różnicy pradów jałowych. Różnicowe zabezpieczenie linii trzy-i czteroprzewodowej na podstawie analizy prądów jałowych.

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