DC-conductivity of insulating oil at lower temperatures

The importance of the characterisation of the DC conductivity increases in use with HVDC equipment. In addition to the AC voltage, HVDC equipment is subject to an additional DC load. For DC stress, the DC conductivity plays a decisive role in the resulting field distribution. To build insulation systems as compact as possible, the behaviour of the DC conductivity must be sufficiently known. The investigations presented here show, on the one hand, how a test vessel must be created so that measurements can be made below the room temperature. On the other hand, measurements of the DC conductivity at lower temperatures are shown. First simulation approaches are illustrated in order to simulate the intended behaviour.