The main function of the sealing oil differential pressure valve 977HP is to regulate the oil and hydrogen pressure difference at the sealing pad of the generator. By using two pressure pipes, the oil pressure and hydrogen pressure at the sealing pad of the generator are fed back to the differential pressure valve. In this way, regardless of how the hydrogen pressure changes, the balance system of the 977HP differential pressure valve can automatically adjust the opening of the valve, accurately control the outlet flow of the differential pressure valve, and ultimately achieve the balance of oil and hydrogen pressure differences.