DEVICE FOR DETERMINING TURN-TO-TURN SHORT CIRCUITS IN POWER TRANSFORMER WINDINGS WITH SWITCHING WITHOUT EXCITATION Russian patent published in 2018 - IPC G01R31/06 H02H3/347 

FIELD: electricity.

SUBSTANCE: device contains current transformers, included into the phase break of the power circuit of the three-phase network, connected to the electric plant. The transformers are interconnected in delta circuit on the sides of the electric plant, forming a differential protection circuit, current circuits and a differential relay with the first and second compensating and differential windings, located on the same core leg and interconnected. The polar terminals of current transformers of different phases and sides of the electric plant are connected to one differential relay. To determine the turn-to-turn short circuit in the windings of the auto-type transformer winding ends are provided. The winding ends have respective digital marking in the number of the changer taps without excitation of the power transformer and allow increasing or decreasing the transformation ratio of the auto-type transformer depending on the changer tap without excitation of the power transformer. The terminals are fitted with pads for changing the turns of the adjustable winding in the number of the transformer phases. Each pad is a metal plate of at least 2.5 mm in cross-section, attached with its one end to the terminal of the dielectric plate, and with the other end to one of the terminals of the adjustable winding of the auto-type transformer, located on the same dielectric plate. The pad is fixed on the terminals of the auto-type transformer.

EFFECT: increase in the sensitivity to turn-to-turn short circuits and elimination of the influence of higher harmonics.

2 cl, 1 dwg