Abstract: Abstract:In a power plant, the differential protection of the electrostatic precipitator transformer tripped incorrectly, which is caused by wiring error of the control loop of the precipitator rectifier cabinet. The fault situation was introduced. The reason of incorrect trip of the differential protection and the reason of the bias excitation of the electric field were analyzed, and the improvement scheme and prevention measures were proposed.

Key words: Keywords:differential protection, bias excitation, DC component, zerocross detection