Abstract:The application defects of typical circuits of 500 kV ultra-high voltage (UHV) switches produced by Siemens, ABB and Mitsubishi are analyzed respectively. An incorrect action case in the test caused by the fault of N2 pressure control circuit of Siemens switch is introduced, and a specific method to judge the fault through three-phase inconsistent transmission mode of single operation power supply is proposed. Aiming at the misoperation risk of three-phase inconsistent circuit of the above three manufacturers, the specific optimization schemes in field application are put forward. Meanwhile, aiming at the possible abnormal phenomena such as opening and closing only once, opening and closing monitoring lights being on at the same time, reclosing discharge and so on due to the mismatch of internal resistance of relay between ABB opening position monitoring circuitand mechanism box trip-preventing circuit, an optimization scheme is proposed that the auxiliary contact and the trip-preventing contact of circuit-breaker are normally closed in series with the opening-position monitoring circuit to automatically disconnect the trip monitoring circuit after the switch is closed or the anti-jump relay is activated. Aiming at the defects that only the first group of operating power supply is used for the lockout relays with low oil pressure and low air pressure in Mitsubishi switch mechanism, which may lead to the loss of power of the first group of operating power supply and the loss of locking of the second group of tripping circuit, an optimization scheme is proposed to add the second group of lockout relays with low oil pressure and low air pressure in series with the second group of tripping circuit.