Design and application of sensor measuring neutral DC current of transformer based on resistance sampling

The Hall sensors could be used in investigating the current of transformer neutral point. However, the closed-loop Hall sensor could not be installed live catenary while the open-loop Hall sensor could not work linearly with the temperature and be corrected online. In the paper, a new type of DC sensor is designed for monitoring the neutral DC current of transformer online and installing live catenary. The output characteristics of designed DC sensor are linear with the working temperature, and easily updated according to the temperature. The measurement error of designed DC sensor used in field measurement is less than 2% or 0.2A when investigating different amplitudes of DC current.