Abstract: Internal short-circuit arc fault in a transformer is the most dangerous fault, and is very likely to cause transformer tank deformation, rupture, and even transformer oil combustion and explosion, which is a serious threat to personnel’s life safety, substation property safety, and power grid operation safety. Realizing the rapid detection of internal short-circuit arc fault in a transformer is conducive to timely signaling the breaker, so as to shorten the arc burning time, cut down the arc energy and reduce the possibility of ignition. To find the signals and characteristics suitable for rapid arc fault detection, we firstly establish an experimental platform of high-current power-frequency arc in oil based on series resonance of capacitor and inductor, and realize the measurements of the key arc characteristics such as voltage, current, pressure wave, light, electromagnetic pulse, and bubble shape.It is found that the pressure wave has two stages of rapid oscillation in the early stage and continuous rise in the late stage, the optical signal has a pulse with an interval of about 10 ms, and the electromagnetic pulse will be generated when the arc current crosses the zero points. The above three signals of pressure wave, light and electromagnetic pulse are expected to be applied to the rapid detection of transformer internal short-circuit arc fault. Finally, we study and compare the advantages and disadvantages of the three fault detection technologies, and point out the problems that need to be solved urgently before the practical application of these methods.