In this paper

it is found through the diagnosis test that the 35 kV shunt reactor in normal operation has inter-turn insulation defect and is in operation state with fault. Such tests as DC resistance

reactance

power frequency loss

inter-turn insulation and lightning impulse are performed on the reactor respectively at site and factory

and the gradual deterioration process of the inter-turn insulation defects is analyzed through data analysis. It is found after the disassembly of the reactor with defect that there are typical wet contamination discharge traces on the 8-3 layer

which is consistent with the test results. The causes of appearance creepage and breakdown are analyzed. The sensitivity and cause analysis of the existing test items to find inter-turn insulation defects is displayed. In combination with such factors as the operating environment and defect characteristics of the dry-type reactor

relevant suggestions for its production process

routine maintenance

maintenance and test item selection are proposed as to ensure that the potential defects of the dry-type reactor can be found in time

prevent the operation with defects

and assure safe and stable operation of the power grid.