Inter-turn short circuit is the main cause of fire accident of dry-type air-core reactor.As for the dry-type air core reactor with suspected inter-turn insulation defect

in this paper

the on-push test method is used to define gradually position of the inter-turn insulation by the use of inter-turn over voltage and temperature rise test

of DC resistance and loss test of each reactor encapsulation as well as dismantling defects.Moreover

the sensitivity of inter-turn insulation defect test is studied with the combination of the damage severity of the insulation medium at the defect position and its topographic features and test suggestion is proposed.It is shown by the study that the test of both inter-turn over voltage and temperature rise have high sensitivity in detecting the inter-turn insulation defects of dry type air-core reactor and the accuracy is within 0.1%.It is necessary to pay more attention to the first-time test result of inter turn overvoltage test so to avoid misjudgment.If the connection between the output wire of electromagnetic lead and connecting parts between wire leads and reactor assembly arms can be disassembled at site

then the site detection rate of the inter-turn insulation defect can be improved significantly.