METHOD FOR TRANSFORMER PROTECTION WITH OLTC AGAINST OVERHEATING Russian patent published in 2020 - IPC H02H7/04 H02H5/04 H01F27/08 G05B13/02 

FIELD: transformers.

SUBSTANCE: invention is related to protection of transformers. Method of transformer protection against on-load tap-changer (OLTC) consists in the following. Voltage and temperature are measured and compared with settings. Active signal is generated when the temperature exceeds the setpoint, and when the temperature drops below the setpoint, the signal "More" and "Less" is generated when the voltage deviates, respectively, at lower and higher settings. Temperature setting is set to 5–10 °C below maximum allowable temperature at measurement point. Measured temperature value is memorized by the above signal of temperature rise above the setpoint OLTC operation is blocked on the voltage deviation channel. Switching to decrease of OLTC by one stage with time delay is secondarily stored the measured temperature value, which is compared with the first stored one, and in case of exceeding the second one above the first one – switching to decrease of OLTC for one more step. In case of temperature stabilization, no actions are taken, and when the temperature drops below the setpoint, the voltage control channel is unblocked.

EFFECT: technical result consists in improvement of reliability.

1 cl, 1 dwg