Development and Application of a Portable 3-axis Transient Magnetic Field Measuring System Based on AMR Sensor

With the development of smart substations, much attention has been focused on the transient magnetic field (TMF) generated during switching operation in substations. In order to study the TMF, a portable integrated system based on Anisotropic Magneto-resistive (AMR) sensor has been developed. The system mainly consists of magnetic probe, sampling card, and industrial computer. A GPS has also been brought in to stamp the TMF events time. This system can record TMF across a bandwidth from DC to 5MHz and a dynamic range from 20mGs to 6Gs for at least 50ms continuously. Laboratory tests show that the system linearity is greater than 97%, the measuring error is less than 3% and the verified rising time of input magnetic field reaches 6.4 mu s. Field applications are presented at last, they show that the TMF is very complex but regular to some extent, and the stable magnetic fields are in conformity with operation theory. In conclusion, the proposed system is high sensitivity, wide dynamic and relatively wide bandwidth, and it is qualified to most applications in substations.