Development of transient current sensor based on tunnel magneto resistance effect

A current sensor for power system monitoring was designed based on the broadband tunnel magneto resistive (TMR) chip. The sensitivity, temperature effect of the chip were tested. To obtain better frequency response characteristic, closed feedback loop was choose for TMR transient current sensor. The performance of the developed TMR sensor was tested by comparing with a standard impulse shunt under $(8/20)\mu \mathrm{s}$ and $(500/750)[\mu\mathrm{s}$ lightning impulse current. The test results show that within the range of 500A current with 0.5ms pulse width, its linearity was better than 0.5%, and the measurement uncertainty of peak current is $1.0\times 10^{-2} (k=2)$ , the measurement uncertainty of time parameters is $1.6\times 10^{-2}(k=2)$ . It can be widely used for current monitoring in power grid.