The creepage on insulation interface of "T" type cable termination is the common defect of 12 kV ring main unit.It will cause insulation resistance degradation of cable in the operational process and the potential safety hazard.Several failure of "T" type cable termination occurred on thesame batch and specification 12 kV ring main unitduring the process of operation and maintenance.The inspection

testing and cause analysis are conducted in this paper.The electric field strength contour of insulation interface of 12 kV ring main unit "T" type cable termination is simulated with FEM in the condition of the failure of insulation grease.The study shows the reason of creepage is that the failure of insulation grease causethe small air gap defecton the insulation interface which results the partial discharge.Theanalysis process provides reference on type-selection optimization

test detection of "T" type cable termination

selection ofinsulation grease

quality control of construction.