Patents by Inventor Keiji Isahaya

Keiji Isahaya 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).

  • Digital distance relay
    Patent number: 4689709
    Abstract: In a digital distance relay, the distance measuring operation is performed only regarding the phase on duty in the third step if there is no fault, and it is performed regarding either the third and first steps or the third and second steps if a fault is detected within the third step. Thereby the processing time for the distance measuring operation may be reduced is that corresponding to two steps per sampling.
    Type: Grant
    Filed: November 6, 1985
    Date of Patent: August 25, 1987
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Keiji Isahaya