The failure occurred most frequently in the dry-type air-core reactor and we cannot detect the inter-turnshort circuit faults in neither single wire winding nor multiple wire windings. The research and protection of reactorfaults is almost in the blank at present. This paper presents the method of collecting the unbalanced current betweenbus-bars to detect the winding inter-turn short circuit faults. The numerical simulation of short circuit model betweendifferent windings of the reactor is carried out. Current-differential analyzed on the unbalanced current data of experi-ment are used to determine whether an inter-turn short circuit occurs. The results indicate that the closer the short-circuit to the end of the reactor

the greater the unbalance current is. The changes of collecting current between bus-bars are much larger than the total current. Compared with the three-phase zero sequence unbalanced current detectturn to turn fault caused by the change of single-phase total current change

the sensitivity is greatly improved.