Insulation of HVDC converter stations

The results of an earlier survey on creepages and clearances in HVDC conver ter stations are expanded with data from a new survey and on-site interview s at several operating terminals. The changes which have accompanied the de velopment of several additional HVDC transmission systems at higher voltage s are illustrated with specific details on external insulation design. A su mmary of insulation performance rind the effectiveness of different mainten ance procedures are discussed.