On-load tap changer, method for installing a load transfer switch insert in the on-load tap changer, and kerosene drain screw

A method of mounting a load changeover switch insert with a switching tube and an oil suction pipe in an on-load tap changer, the method comprising the following steps:

• inserting the load changeover switch insert together with the switching tube into an oil tank of the on-load tap changer such that the switching tube is offset from an axis of the on-load tap changer;
• positioning the switching tube that has a bearing at a lower end, on a bearing ring that is acted on at one side and radially with respect to the axis of the on-load tap changer by a resilient element such that an axis of the switching tube is offset from the axis of the on-load tap changer;
• placing the oil suction pipe on a domed protrusion that is formed in fixed location coaxially with respect to the axis of the on-load tap changer of a base such that a guided positioning is made possible by a cone guide at an inner side of the switching tube;
• and
• centering the switching tube and the oil suction pipe with respect to the axis of the on-load tap changer by urging the bearing ring by the resilient element to be centered with respect to the axis of the on-load tap changer by the cooperation of a suction stub pipe at the lower end of the oil suction pipe, with the bearing ring and with the stationary domed protrusion of the base.