04929903 is referenced by 20 patents and cites 9 patents.

A method of and apparatus for the detection of insulation deterioration in an electrical power supply system utilizes the detection of a progressive wave generated by a corona discharge or partial discharge due to such insulation deterioration. Sensing of said progressive wave may be effected by an apparatus comprising: a first coil having two primary windings, wound with the same number of turns and in the same direction, and a secondary winding, the primary and secondary windings being wound on a core whose magnetomotive force and magnetic flux density are roughly proportional to each other; a second coil composed of a primary winding and a secondary winding both wound on a core whose magnetomotive force and magnetic flux density are roughly proportional to each other; and an impedance circuit. Determination of the position of insulation deterioration may be effected by comparing the phase of the progressive wave at a reference point in a common bus with the phase of the progressive wave in each of the power supply lines branching off from the common bus.

Title
Method of and apparatus for assessing insulation conditions
Application Number
7/228578
Publication Number
4929903
Application Date
August 5, 1988
Publication Date
May 29, 1990
Inventor
Junji Suehiro
Otake
JP
Akio Sera
Kuga
JP
Keizaburo Ishikura
Kuga
JP
Tomoaki Kageyama
Kuga
JP
Shigenari Maezawa
Kashiwa
JP
Akira Saigo
Chiba
JP
Agent
Sherman and Shalloway
Assignee
Mitsui Petrochemical
JP
IPC
G01R 31/02
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