Patents by Inventor Kuniyoshi Sakai

Kuniyoshi Sakai 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).

  • Patent number: 7161354
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Grant
    Filed: March 23, 2005
    Date of Patent: January 9, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami
  • Patent number: 7110895
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Grant
    Filed: October 4, 2002
    Date of Patent: September 19, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami
  • Publication number: 20060020406
    Abstract: A measurement method is disclosed for measuring the resistance component leakage current included in the leakage current and the resistance value that is an insulation resistance to monitor the insulation state of a distribution system. The signal waveform of at least one AC cycle is sampled in the resistance component leakage current measurement from the leakage current signal and the voltage signal of a current transformer of target measurement circuit, and the resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values.
    Type: Application
    Filed: July 11, 2005
    Publication date: January 26, 2006
    Applicant: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami, Nobuyuki Kawauchi
  • Publication number: 20050200364
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Application
    Filed: March 23, 2005
    Publication date: September 15, 2005
    Applicant: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami
  • Patent number: 6922643
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Grant
    Filed: May 27, 2004
    Date of Patent: July 26, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami
  • Publication number: 20040220759
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Application
    Filed: May 27, 2004
    Publication date: November 4, 2004
    Applicant: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami
  • Publication number: 20030112015
    Abstract: A method for measuring the resistance component current included in the leakage current is provided. In a monitoring apparatus and system for measurement the signal waveform of at least one AC cycle is sampled. The resistance component leakage current is measured by dividing the average of integrated value of the instantaneous leakage current values and the instantaneous voltage values by the square root of average of squared instantaneous voltage values. In addition, a voltage signal of the target measurement circuit is obtained the waveform of the leakage current signal and the voltage signal for one cycle is sampled and stored; the leakage current signal and the voltage signal are expanded to N-th higher harmonic wave component respectively, and the resistance component that relates to the leakage current is calculated.
    Type: Application
    Filed: October 4, 2002
    Publication date: June 19, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Naohiro Takakamo, Kuniyoshi Sakai, Yoshikazu Terakami