SIGNALLING SYSTEM RESPONSIVE TO FAULT ON ELECTRIC POWER LINE

• US 3,708,724 A
• Filed: 03/31/1972
• Issued: 01/02/1973
• Est. Priority Date: 03/31/1972
• Status: Expired due to Term

• Current Assignee: Edmund O. Schweitzer Jr
• Original Assignee: Edmund O. Schweitzer Jr
• Inventors: Schweitzer, Edmund O. Jr.
• Primary Examiner(s): Trammell, James D.
• Application Number:
  US05/239,930
• Time in Patent Office: 277 Days
• Field of Search: 324/132,133,127,51 340/253A,255,373 317/22,33SC,33C
• US Class Current: 361/75
• CPC Class Codes: G01R 19/16509 using electromagnetic relays, e.g. reed relay magnetically driven reeds G01R9/06
• CPC Class Codes: H01H 71/2445 using a reed switch for current measuring G01R19/16509

Abstract

One or more reed switches have contacts that are held closed on normal energization or current flow in an alternating current conductor and are opened on flow of alternating current in the conductor above a predetermined value. The switch or switches may be potted in a cavity in an insulator supporting the conductor. A rectifier energized from the conductor charges a capacitor the discharge from which through winding means effects closure of the contacts.

Claims

1. A signalling system for an alternating current conductor energized at a relatively high voltage above ground comprising:

a reed switch containing a pair of magnetic contacts spring biased to one position for connection to a signalling circuit, a relatively low coercive force U-shaped magnetic core with the arms extending along the lines of alternating magnetic flux surrounding said conductor and generated by flow of alternating current in said conductor and their distal ends adjacent the terminals of said contacts of said reed switch, magnetizing winding means on said core, a trigger circuit, a capacitor connected in series with said trigger circuit and across said magnetizing winding means, rectifier means connected to charge said capacitor, and circuit means for electrostatic connection between said conductor and ground for energizing said rectifier means, said trigger circuit periodically discharging said capacitor through said winding means to magnetize said core and hold said contacts in another position, said core being demagnetized by said alternating magnetic flux around said conductor on flow therethrough of alternating current above a predetermined value to shift said contacts to said one position.

2. Signalling system according to claim 1 wherein a hollow insulator for supporting said conductor has said signalling system enclosed therein.

3. Signalling system according to claim 1 wherein said contacts are spring biased to open position.

4. Signalling system according to claim 1 wherein the longitudinal axis of said reed switch is transverse to the longitudinal axes of said arms.

5. Signalling systeM according to claim 1 wherein said magnetizing means comprises a winding on one of said arms of said core.

6. Signalling system according to claim 1 wherein said magnetizing means comprises a winding on each arm of said core.

7. Signalling system according to claim 1 wherein said trigger circuit includes gated semiconductor means shunted by a space discharge device rendered conducting when the charge on said capacitor reaches a predetermined value.

8. Signalling system according to claim 1 wherein circuit means interconnect said reed switch and said rectifier means to discharge said capacitor when said contacts occupy said other position to prevent application of repeated magnetizing pulses to said winding means from said capacitor, said magnetic core having sufficient retentivity to hold said contacts in said other position.

9. A signalling system for an alternating current conductor energized at a relatively high voltage above ground comprising:

reed switch means containing at least one pair of magnetic contacts spring biased to one position for connection to a signalling circuit and for location adjacent said conductor with the longitudinal axis along the lines of magnetic flux surrounding said conductor generated by flow of alternating current in said conductor, a permanent magnet adjacent the terminals of said contacts and biasing them toward another position, winding means adjacent said reed switch means, and means for energization from said conductor for energizing sad winding means with direct current to assist said permanent magnet means in shifting said contact means to said other position, the magnetic fields from said permanent magnet and said winding means being reduced by said alternating magnetic flux around said conductor on flow therethrough of alternating current above a predetermined value to shift said contacts to said one position.

10. Signalling system according to claim 9 wherein said reed switch means comprises a pair of reed switches connected in series circuit relation.

11. Signalling system according to claim 10 wherein a magnetic shunt is located adjacent corresponding ends of said reed switches, and said permanent magnet is located adjacent the other ends of said reed switches.

12. Signalling system according to claim 9 wherein the biasing action of said permanent magnet is less than that required to shift said contacts to said other position, and said winding means surrounds said reed switch and when energized shifts said contact means to said other position.

13. Signalling system according to claim 9 wherein said means for energizing said winding means comprises rectifier means energized by alternating current derived from said conductor to charge a capacitor connected in series with a space discharge device across said winding means and rendered conducting when said capacitor is charged to a predetermined value.

14. Signalling system according to claim 13 wherein said rectifier means is energized from the secondary winding of a transformer the primary winding of which is energized from said conductor.

15. Signalling system according to claim 13 wherein said rectifier means is energized through electrostatic connecting means from said conductor.

16. Signalling system according to claim 9 wherein said means for energizing said winding means comprises rectifier means energized by alternating current derived from said conductor to charge a capacitor connected in series with gated semiconductor means triggered by a space discharge device rendered conducting when the charge on said capacitor reaches a predetermined value.