As a new technique

DC MOA of transmission line is first applied on the transmission line in 2013.In order to study the running conditions and the existential questions in the running process of the DC MOA

the running condition of the trial operation of DC MOA on DC ±500 k V transmission line is tracking studied

the running condition shown that the lightning faults of the DC ±500 k V transmission line decreased significantly after the DC MOA installed

but the majority of DC MOA counter has no action. The field sampling detection of the DC MOA is carried out by the authors

the test results shown that only one DC MOA counter existing defects

and the insulation resistance of the insulation base decreased significantly. The author holds that the low insulation of the insulation base maybe one of the reasons for the no action of the counters

insulating components aging and contamination accumulation and insulated porcelain damaged and other reasons all can result in insulation resistance decreased significantly. The suggestions of add a flexibility insulating sheath to the porcelain insulation base or changing the insulation base material are proposed

and the criterion of the insulation resistance for the MOA insulation base should unified is also proposed in the paper.