METHOD OF ARRANGEMENT AND ADJUSTMENT OF HIGH FREQUENCY DIRECTIONAL RELAY LINE PROTECTION Russian patent published in 2010 - IPC H02H3/08 

FIELD: electricity.

SUBSTANCE: hardware operating at high voltage potential, and primary winding of power supply transformers are connected to each line end in parallel to the interval of each power wire. Voltage drop is measured from current flowing in this interval from each line end deep into the circuit. High carrying frequency generators are started for the given protected line to operate during each positive half-cycle of industrial current relative to line ends. Then voltage is supplied to opposite ends of fault wire and primary winding of power supply transformer is connected at each line end in parallel to power wire. The secondary windings are used to form electrically isolated d.c. outputs. Each power wire current is measured at each line ends by means of by-pass. Current exceeding levels are monitored. High-frequency signal is selected from the resultant current and high-frequency component is filtered out. As a result, pulses and logical signal of level exceeding are isolated by means of electronic and optical transformation. Rectangular pulses during industrial current half-cycles and logical signal on safe signal near earth are used as a pause between intervals, which are no less than the given value of industrial frequency period. In order to detect faulty line, logical pause signal exceeding the given value is logically multiplied by the exceeding signal of the given current value. The result is used to turn off switches of the given ends.

EFFECT: simplifying signal scaling, measuring and transformation operations for line power currents.

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