PROTECTIVE DEVICE FOR TWO PARALLEL LINES Russian patent published in 2014 - IPC H02H7/00 H02H7/26 

FIELD: electricity.

SUBSTANCE: the device comprises the first, second and third current relays coupled to secondary windings of the current transformers for the respective A, B, C phases of the first line; the fourth, fifth and sixth current relays coupled to secondary windings of the current transformers for the respective A, B, C phases of the second line, the first, second, third and fourth AND elements and each of the above elements is coupled to the respective current relay. The first OR element is connected to the first, second and third AND elements. The first multiplier and the fourth comparing element are coupled to the secondary winding of the phase A of the current transformer in the first line. The second multiplier and the fifth comparing element are coupled to the secondary winding of the phase B of the current transformer in the first line. The third multiplier and the sixth comparing element are coupled to the secondary winding of the phase C of the current transformer in the first line. The fourth multiplier and the first comparing element are coupled to the secondary winding of the phase A of the current transformer in the second line. The fifth multiplier and the second comparing element are coupled to the secondary winding of the phase B of the current transformer in the second line. The sixth multiplier and the third comparing element are coupled to the secondary winding of the phase C of the current transformer in the second line. The fifth and sixth AND elements are coupled to the second OR element.

EFFECT: device reliability improvement.

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