MAIN TRANSFORMER NEUTRAL POINT OVERVOLTAGE PROTECTION DEVICE

摘要

A main transformer neutral point overvoltage protection device is characterized by comprising a base (5), a transient high-frequency overvoltage absorption protection unit (a) and a rod gap power frequency overvoltage protection unit (b), wherein the transient high-frequency overvoltage absorption protection unit and the rod gap power frequency overvoltage protection unit are installed on the base and are connected in parallel. In the transient high-frequency overvoltage absorption protection unit, a lightning arrester (6, 7) and a capacitor (2) are combined, the neutral point lightning arrester is divided into an upper segment and a lower segment that are connected in series, the lower segment of the lightning arrester (7) is connected with the capacitor in parallel, and due to the bypass absorption capacity of the capacitor for transient high-frequency overvoltage, the lightning and operation residual voltage is 40% lower than that of an existing commonly-used neutral point lightning arrester on the premise that the power frequency residual voltage of the lightning arrester is kept higher than the upper limit of the rod gap power frequency discharge voltage. Compared with an existing commonly-used neutral point protection product with a rod gap and a lightning arrester connected in parallel, the situation that because the rod gap discharges frequently when lightning invades, abnormal action occurs in relay protection and a main transformer is cut off can be remarkably improved.