Patents by Inventor Robert W. Vreeland

Robert W. Vreeland 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).

  • Transient-free isolation monitor
    Patent number: 3961224
    Abstract: Line isolation monitor utlizing photoisolators to effect switching without transients. Phase-lift networks are connected between the conductors of an isolated power system to provide samples to be monitored. A photoisolator comprising a light-emitting diode (LED) and a photoresistor is connected between each of the phase-shift networks and a current monitor, and the LEDs are energized alternately to apply the signals to the monitor. Timing circuits are included for preventing one photoisolator from being turned on while the other is still conducting.
    Type: Grant
    Filed: January 30, 1975
    Date of Patent: June 1, 1976
    Assignee: The Regents of the University of California
    Inventor: Robert W. Vreeland