Patents by Inventor Kajuaki Kumagai

Kajuaki Kumagai has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method and apparatus for protecting a power transmission line
    Patent number: 5543995
    Abstract: Method and apparatus for preventing reclosing of circuit breakers to reconnect a transmission line when a break fault occurs in the transmission line. A voltage at a fault point is estimated from opposite ends of the transmission line, and when those voltages are not equal, the break fault of the transmission line is determined, the break fault is displayed and the reclosing by a protective relay is prevented. By specifying a fault of the transmission line as a break fault, a recovery time of the transmission time is significantly reduced and an equipment is protected because the closing of the circuit breaker is blocked during the fault.
    Type: Grant
    Filed: June 1, 1993
    Date of Patent: August 6, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Kajuaki Kumagai, Hiroshi Takiguchi, Shigeru Abe