Fault indicator providing light indication on fault detection

• US 6,433,698 B1
• Filed: 03/30/1999
• Issued: 08/13/2002
• Est. Priority Date: 04/30/1998
• Status: Expired due to Fees

• Current Assignee: Schweitzer Engineering Laboratories, Incorporated
• Original Assignee: E.O. Schweitzer Manufacturing Compay, LLC
• Inventors: Thomas, Kirk S., Schweitzer, Edmund O. Jr.
• Primary Examiner(s): Wu, Daniel J.
• Application Number:
  US09/281,012
• Time in Patent Office: 1,232 Days
• Field of Search: 340/635, 340/664, 340/657, 340/691.6, 361/91, 361/1, 361/93, 324/133, 324/418, 324/419
• US Class Current: 340/664
• CPC Class Codes: G01R 19/16509 using electromagnetic relays, e.g. reed relay magnetically driven reeds G01R9/06

Abstract

A fault indicator for detecting the occurrence of a fault current in a monitored conductor and providing a light indication thereof includes a rotatably mounted indicator flag. The flag is positioned in either a reset indicating or a fault indicating state by a magnetic pole piece, which is magnetized in one magnetic direction or the other by momentary application of a current in one direction or the other to an actuator winding on the pole piece. A magnetically actuated reed switch in an auxiliary magnetic circuit comprising an auxiliary pole piece magnetized by the actuator winding and a bias magnet magnetically aligned to oppose the reset magnetic orientation and reenforce the trip magnetic orientation of the magnetic pole piece closes upon occurrence of the fault current to connect an internal lithium battery to an LED visible from the exterior of the fault indicator housing.

Claims

1. A fault indicator for indicating the occurrence of a fault current in an electrical conductor, comprising:

a housing;

a battery;

a lamp operable from said battery and viewable from the exterior of the housing;

a magnetic circuit including a magnetic pole piece, a magnetically actuated switch and a bias magnet, said bias magnet having a magnetic polarity which opposes a magnetic field in said magnetic pole piece in one direction, and reenforces a magnetic field in said magnetic pole piece in the other direction, whereby said magnetically actuated switch is conditioned to open in response to a magnetic field in said one direction and closed in response to a magnetic field in said other direction;

circuit means including a magnetic winding in magnetic communication with said magnetic pole piece and responsive to the current in the monitored conductor for developing a magnetic field in said pole piece in a direction to condition said switch open during normal current flow in the monitored conductor, and for developing a magnetic field in said pole piece in said opposite direction to condition said switch closed upon occurrence of a fault current in the conductor; and

said magnetically actuated switch connecting said battery to said lamp whereby said lamp lights in said fault indicating state.

2. A fault indicator as defined in claim 1 wherein said magnetic pole piece includes a pair of spaced-apart magnetic poles, and said magnetically actuated switch is disposed between said poles.

3. A fault indicator as defined in claim 2 wherein said magnetically actuated switch includes a pair of projecting leads, and said leads are mechanically connected to but electrically isolated from said magnetic poles.

4. A fault indicator as defined in claim 3 wherein said magnetically actuated switch comprises a reed switch.

5. A fault indicator as defined in claim 4 wherein the axis of said reed switch is aligned generally parallel to the axis of said monitored conductor.

6. A fault indicator as defined in claim 5 wherein said magnetic pole piece is generally U-shaped.

7. A fault indicator for indicating the occurrence of a fault current in an electrical conductor, comprising:

a housing;

a battery;

a lamp operable from said battery and viewable from the exterior of said housing;

an indicator flag assembly including an indicator flag viewable from the exterior of the housing and a first magnetic pole piece, said indicator flag being magnetized and in magnetic communication with said first magnetic pole piece whereby said indicator flag is actuated to a reset-indicating position by a magnetic field in said first magnetic pole piece in one direction, and is actuated to a fault-indicating position by a magnetic field in said first magnetic pole piece in the opposite direction;

a magnetic circuit including a second magnetic pole piece, a magnetically actuated switch and a bias magnet, said bias magnet having a magnetic polarity which opposes a magnetic field in said second magnetic pole piece in one direction, and reenforces a magnetic field in said second magnetic pole piece in the other direction, whereby said magnetically actuated switch is actuated open in response to a magnetic field in said one direction and closed in response to a magnetic field in said other direction;

circuit means including a magnetic winding in magnetic communication with said first and second magnetic pole pieces and responsive to the current in the monitored conductor for developing a magnetic field in said one direction in said pole pieces to position said indicator flag to said reset indicating position and condition said magnetically actuated switch open during normal current flow in the monitored conductor, and for developing a magnetic field in said opposite direction in said pole pieces to position said indicator flag in said fault indicating position and condition said magnetically actuated contacts closed upon occurrence of a fault current in the conductor; and

said magnetically actuated switch connecting said battery to said lamp whereby said lamp lights in said fault indicating state.

8. A fault indicator as defined in claim 7 wherein said magnetic pole piece includes a pair of spaced-apart magnetic poles, and said magnetically actuated switch is disposed between said poles.

9. A fault indicator as defined in claim 8 wherein said magnetically actuated switch includes a pair of projecting leads, and said leads are mechanically connected to but electrically isolated from said magnetic poles.

10. A fault indicator as defined in claim 9 wherein said magnetically actuated switch comprises a reed switch.

11. A fault indicator as defined in claim 10 wherein the axis of said reed switch is aligned generally parallel to the axis of said monitored conductor.

12. A fault indicator for indicating the occurrence of a fault current in an electrical conductor, comprising:

a housing;

a battery;

a lamp operable from said battery and viewable from the exterior of the housing;

a rotatably mounted indicator flag viewable from the exterior of said housing;

a first magnetic pole piece having magnetic poles in magnetic communication with said indicator flag, said flag assuming a reset-indicating position in response to a magnetic field in said first magnetic pole piece in one direction and a trip-indicating position in response to a magnetic field in said first magnetic pole piece in the other direction;

a magnetically actuated switch;

a second magnetic pole piece having magnetic poles in magnetic communication with said magnetically actuated switch, and a bias magnet opposing a magnetic field in said second magnetic pole piece in said one direction and reenforcing a magnetic field in said second magnetic pole piece in said other direction whereby said magnetically actuated switch is actuated to open in response to a magnetic field in said one direction and is actuated closed in response to a magnetic field in said second magnetic pole piece in said other direction;

circuit means including a magnetic actuator winding in magnetic communication with said first and second magnetic pole pieces for inducing magnetic field in said one direction in each of said pole pieces when said fault indicator is in a reset state, and in said other direction when said fault indicator is in a trip state;

said magnetically actuated switch connecting said battery to said lamp whereby said lamp lights in said fault indicating state.

13. A fault indicator as defined in claim 12 wherein said auxiliary magnetic pole piece includes a pair of spaced-apart magnetic poles, and said magnetically actuated switch is disposed between said poles.

14. A fault indicator as defined in claim 13 wherein said magnetically actuated switch includes a pair of projecting leads, and said leads are mechanically connected to but electrically isolated from said magnetic poles.

15. A fault indicator as defined in claim 14 wherein said magnetically actuated switch comprises a reed switch.

16. A fault indicator as defined in claim 15 wherein the axis of said reed switch is aligned generally parallel to the axis of said monitored conductor.

17. A fault indicator as defined in claims 12 wherein said auxiliary magnetic pole piece is generally U-shaped.

18. A fault indicator as defined in claim 17 wherein said actuator winding is wound on the transverse portion of said first and second U-shaped magnetic pole pieces.