Experimental Investigation on the Condensation of Characteristics of 12kV Ring Main Unit

Ring main unit is widely used in power distribution system, but the condensation of ring main unit will cause the failure of switchgear and harm the safety of power system. According to statistics, flashover accidents caused by condensation account for a large proportion of the accidents occurring in the switchgear. In this paper, the relationship between the top ventilation grille, the structure of the contact box, the heater position and working current and condensation was experimentally studied by using a 12kV ring main unit. The results show that the humidity of the busbar room decreases when the ventilation grid exists, but it has little influence on the temperature in the cabinet. The outlet of the busbar of the contact box is blocked, which can effectively reduce the airflow flow in the cabinet and help to reduce the humidity in the switchgear. After sealing the outlet of busbar, the humidity in the cabinet can be reduced by 20%. The dehumidification effect is better when the heater works close to the side wall. The higher the working current, the better the condensation inhibition in the switch cabinet.