Patents by Inventor Sakai Kuniyoshi

Sakai Kuniyoshi 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).

  • Leakage current or resistance measurement method, and monitoring apparatus and monitoring system of the same
    Patent number: 7353123
    Abstract: A measurement method is disclosed for measuring the resistance component leakage current. The signal waveform of at least one AC cycle is sampled in the resistance component leakage current measurement, and the resistance component leakage current is measured. A zero-cross detecting circuit for detecting a voltage zero-crossing point of the target measurement circuit and outputting a sampling start signal is provided, voltage digital data of the sine wave form whose effective value is 1 and the output signal of the zero-phase current transformer are sampled, and the products of multiplication are averaged by synchronizing the sampled output signal value and the voltage digital data to obtain an active leakage component current of leakage currents.
    Type: Grant
    Filed: July 11, 2005
    Date of Patent: April 1, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Sakai Kuniyoshi, Nobuyuki Kawauchi