ON-LOAD TAP CHANGER

PROBLEM TO BE SOLVED: To provide an on-load tap changer capable of surely preventing occurrence of shutoff mistake even when a direct current is carried to a main valve, and exhibiting excellent insulation performance and stable shutoff capability. SOLUTION: This on-load tap changer is structured such that the main valve H is opened in a state where a valve W1 for resistance on the side of a tap 2 carrying a current before a change operation is opened and a valve W2 for resistance on the side of a tap 3 not carrying a current before the change operation is opened; the valve W2 for resistance on the tap 3 side is opened in a state where the main valve H is opened, the valve W1 for resistance on the tap 2 side which is carrying a current before the change operation is closed, and the valve W2 for resistance on the tap 3 side not carrying a current before the change operation is opened; and thereafter, a moving contact SC of a changing-over switch S starts operation to open electrical connection to a fixed contact SA in contact with it before the change operation. COPYRIGHT: (C)2010,JPO&INPIT