Granted Patent
Utility
US 4,935,837 · App. 07/332,186
Phase comparison relaying system with single channel communications link
Inventor:
Shan C. Sun
Patented Case
View Patent ↗
Granted: Jun 19, 1990
Filed: Apr 3, 1989
Inventor
Shan C. Sun
Assignee (at issue)
ABB Power T&D Company Inc.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.