On-line monitoring system for DC magnetic bias current of transformer

The invention discloses an on-line monitoring system for a DC magnetic bias current of a transformer, and the system comprises a Hall sensor which is installed at a transformer neutral point. A signal output end of the Hall sensor is connected to a signal input end of an A/D converter, and a signal output end of the A/D converter is connected to a single-chip microcomputer. The system also comprises a wireless transmission module, and the wireless transmission module is also connected to the single-chip microcomputer. According to the invention, the Hall sensor is disposed at the transformer neutral point nearby a DC grounding electrode, and the wiring of the transformer neutral point is not change. The system employs the measurement data of the distribution of DC bias currents, is provided with an alarm threshold value, achieves the real-time monitoring of the DC bias current of the transformer, improves the early warning capability of a power grid transformer for the DC bias, and is convenient to timely take effective protection measures for the transformer with a bigger risk of DC bias.