Fault is frequently occurred in dry type reactor. It is shown by the fault analysis that all the burnt reactors have had inter-turn short circuit fault. It is known by the Maxwell equation that a reactor with interturn short circuit fault is equivalent to a dry-type air-core auto-transformer

with fewer turns and large transformation ratio at low voltage side. The current density in the short-circuit loop exceeds the normal designed value and the short-circuit loop can burn capacitor due to serious overheating

and thus cause a fire. In order to find out the inter-turn short circuit fault of the dry reactor in time

in this paper

the healthy condition of the reactor is analyzed through the variation of unbalance flux before and after the inter-turn short circuit of the reactor at the symmetrical center position of dry shunt reactor with three-phase pattern layout

and the verification result is inspected by way of simulating inter-turn short circuit test method

showing that the inter-turn short circuit fault of dry reactor with pattern layout and the leakage magnetic field variation of the symmetrical center position have an association relation.