METHOD FOR IDENTIFICATION OF WINDING SHORT CIRCUITS IN WINDINGS OF THREE-PHASE TRANSFORMERS Russian patent published in 2018 - IPC G01R31/06 

FIELD: power engineering.

SUBSTANCE: invention relates to the electric power engineering and can be used to detect the winding short circuits in the windings of three-phase transformers. Method is based on of active power and voltage measurements at open-circuit operation. Measurements are made in the absence of connections between the transformer windings, except for the common point in the star arrangement. Measurements are performed alternately by supplying of the industrial frequency operational voltage from the regulated power source to only one primary or secondary winding at the beginning of the first phase of the transformer. At that, measuring the amount of active power consumed from the power source and recording this value. Simultaneously, measuring and recording the voltages values on both windings of the first phase. Then, supplying the operational voltage of the previous value to the primary or secondary winding of the second phase of the transformer. Measuring and recording the active power value for the second phase and the values of the voltages on the second phase windings. Further, the active power and voltage for the third phase are measured and recorded in a similar manner. Next, the registered active power values for three phases are compared with each other and, according to the largest of these values, a conclusion is made about the presence of a winding short circuit in some of the windings of the corresponding phase of the transformer. According to the registered voltage values of the windings of the detected damaged phase, the values of the actual transformation ratio between the windings of this phase are calculated for two probable cases of the winding short circuit in the primary or secondary winding. Then the coefficient calculated values are compared with the nominal transformation ratio. If the actual coefficient is less than the nominal coefficient, then a final conclusion is made about the fact of the winding short circuit in the primary winding, with the inverse ratio of the coefficients, on the contrary, in the secondary winding.

EFFECT: technical result is increase in the reliability of damaged windings detection.

1 cl, 2 dwg