Monitoring the condition of an insulator

• US 4,224,612 A
• Filed: 05/12/1978
• Issued: 09/23/1980
• Est. Priority Date: 05/12/1977
• Status: Expired due to Term

• Current Assignee: Roy E. Macey
• Original Assignee: Roy E. Macey
• Inventors: Macey, Roy E.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US05/905,606
• Time in Patent Office: 865 Days
• Field of Search: 340/647, 340/375, 340/376, 340/664, 361/132, 361/133, 361/118, 361/131, 174/139, 174/140 R, 174/141 R, 174/144, 174/150, 200/61.08, 200/61.52, 200/61.83
• US Class Current: 340/647
• CPC Class Codes: G01R 31/1245 of line insulators or spacers, e.g. ceramic overhead line cap insulators; of insulators in HV bushings
• CPC Class Codes: H01B 17/42 Means for obtaining improved distribution of voltage capacitor-type lead-through insulators H01B17/28; Protection against arc discharges

Abstract

A method of continuously monitoring the condition of a power transmission line insulator while it is in service, in which part of the insulator is bypassed by conductive means and in which, when the leakage current passed by the insulator and flowing through the conductive means exceeds a predetermined value, the conductive means is severed by a detonator or other explosive charge and actuating means is actuated which is operative to give a remote indication. Also a sensing and actuating device for use in the method, having conductive means and being adapted to be attached to an insulator so as to bypass part of it, which includes a detonator or other explosive charge adapted to sever the conductive means when leakage current through it exceeds a predetermined value and actuating means in the form of a mercury switch which is operable to give a remote indication when this happens.

Claims

1. A device for monitoring a condition of power transmission line insulators on a power line pylon comprising

an electrically conductive element for connecting to the power line pylon,

electrically conductive means for connection to an insulator at a point insulated from the power line pylon,

sensing means connected between said electrically conductive element and said electrically conductive means for carrying in a conductive path with said electrically conductive element and said electrically conductive means, substantially all of the leakage current between the insulated point and the pylon to electrically bypass the insulation between the insulated point and the pylon,

said sensing means including

severing means responsive to the leakage current between the insulated point and the pylon to cause a break between said electrically conductive element and said electrically conductive means when the leakage current exceeds a predetermined value in said conductive path and to render the previously bypassed insulated point and the pylon without a bypass,

and indicating means to indicate that the leakage current has exceeded a predetermined value actuated by said severing means moving said electrically conductive element and said electrically conductive means apart.

2. The device of claim 1 further characterized by

said severing means including

an electrically operable detonator having a fuse wire which forms part of said conductive path, said detonator being detonatable upon the leakage current passing through said conductive path exceeding said predetermined value.

3. The device of claim 2 further characterized by

said severing means including

an explosive charge in which said detonator is embedded.

4. The device of claim 2 further characterized by

said severing means including

a pair of conductive tubes which fit together telescopically to establish electrical contact with each other and which are closed at their ends remote from one another so as together to define an enclosed space, said detonator positioned within said enclosed space whereupon when said detonator is detonated, an explosive force causes said two tubes to fly apart, breaking electrical contact between them and thus severing said conductive path.

5. A method of continuously monitoring the condition of an electrical power transmission line insulator while it is in service comprising the steps of

bypassing part of the insulator to establish an electrically conductive path between a power line pylon and a point on said insulator insulated from the power line pylon to conduct substantially all of the leakage current through said conductive path,

automatically removing the bypass when the leakage current exceeds a predetermined value and rendering the previously bypassed part of the insulator operative as insulation without a bypassing electrically conductive path between said point on the insulator and the pylon,

actuating an indicating means to indicate that the leakage current has exceeded said predetermined value.

6. The method of claim 5 further characterized by performing the step of

automatically removing the bypass when the leakage current exceeds a predetermined value by detonating explosive means to sever said conductive path.

7. A method as claimed in claim 5, wherein said predetermined value is at least 100 mA.

8. A sensing and actuating device for monitoring the condition of a power transmission line insulator, which device comprises:

an electrically conductive element for connecting to a power line pylon;

electrically conductive means for connection to the insulator, intermediate the ends of the insulator;

sensing means connected between said electrically conductive element and said electrically conductive means for carrying leakage current from the insulator to the pylon and being responsive to such leakage current to cause a break in the connection between the electrically conductive element and the electrically conductive means when the leakage current exceeds a predetermined value, whereby said electrically conductive element will move clear of said electrically conductive means; and

actuating means associated with said electrically conductive element for actuating indicating means remote from the pylon when said electrically conductive element has moved clear of the electrically conductive means so as to indicate that the leakage current has exceeded said predetermined value and therefore that the condition of the insulator has fallen below a certain standard.

9. A sensing and actuating device as claimed in claim 8, wherein the actuating means is in the form of a position sensitive switch.

10. A sensing and actuating device as claimed in claim 9, wherein the position sensitive switch is a mercury switch.

11. A sensing and actuating device as claimed in claim 9, which further comprises one or more leads connected to the switch, for connecting the switch to said indicating means;

and wherein said electrically conductive element includes a tube of electrically conductive material, said lead or leads passing through the tube.