POWER TRANSFORMER PROTECTION PACKAGE Russian patent published in 2019 - IPC H02H7/04 

FIELD: electrical engineering.

SUBSTANCE: protection package of the power transformer using the de-shunting of the tripping coils contains matching intermediate transformers with a variable number of turns of the secondary winding, it has two arms of signal processing, respectively, from current transformers on the sides of high and low voltages. Current from the current transformers goes to the intermediate transformers, from where to the rectifier diode blocks, where the negative half-wave is separated therefrom. Then the positive half-waves arrive at the blocks of the operational amplifiers and comparators, at the outputs of which rectangular pulses are obtained, which arrive at the input of the node of the AND-NOT logic element. In the event of a short circuit within the differential protection zone, the impulses from the comparators go non-synchronously, thus, a positive signal is generated at the output of the AND-NOT logic gate, which is registered by the trigger node, which gives the microcontroller the command to immediately de-shunt the tripping electromagnets of the high-voltage switches that are tripped by the symistors. With through short-circuit currents, the overcurrent protection operates, which receives signals from intermediate transformers, and the negative half-wave is also separated. Positive half-waves fall on the blocks of operational amplifiers, where they are compared with the reference voltage, which is the setting of the current protection. If the current exceeds the current setting, then a positive signal is sent to the comparators, and from them to the microcontroller, which will give a signal to turn off the power transformer. To determine the time to shutdown (exposure), the real current is determined through filter-rectifier blocks connected to intermediate transformers, in which the alternating current is rectified, smoothed, and all frequencies apart from the power frequency are separated. Rectified voltage is fed to the input of the analog-digital converter of the microcontroller. Reference voltage is used as an independent time setting.

EFFECT: technical result is increased reliability, enhanced functionality of the protection package of a power transformer.

1 cl, 6 dwg