DEVICE FOR OFFSET FROM MAGNETISATION CURRENT RUSH DURING CONNECTION UNDER VOLTAGE FOR TRANSFORMER DIFFERENTIAL PROTECTION Russian patent published in 2016 - IPC H02H7/45 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, namely to differential protection, and can be used for differential protection of transformers. Said technical result is achieved by that a device for offset from magnetisation current rush during connection under voltage for transformer differential protection generates rectified signals proportional to currents of direct, reverse and zero-sequence, by means of three secondary six-phase windings of transformers with rotary magnetic field, which are connected by their primary windings to current in each phase, then rectified signal reverse sequence is divided into rectified signal of direct sequence and compared with content of reverse sequence relative to direct sequence to form first input of an OR circuit, sum of rectified signals of signals reverse and zero-sequence is divided into rectified signal of direct sequence and compared with setting total reverse and zero-sequence relative to direct sequence, thus forming second input to OR circuit, which generates a signal off if corresponding settings or outputs a signal to locking differential protection actuation.

EFFECT: technical effect of proposed device is detuning of magnetisation current rush during connection under voltage for differential protection of transformers, which does not cause slowing at saturation current transformers in range to fifty percent of current error of transformer current, high sensitivity of differential protection on actuation current below 0,3I_rated of power transformer.

1 cl, 1 dwg