Fault indicator providing contact closure and light indication on fault detection

• US 6,016,105 A
• Filed: 07/17/1998
• Issued: 01/18/2000
• 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 (Schweitzer Engineering Laboratories, Incorporated)
• Inventors: Schweitzer, Edmund O. Jr.
• Primary Examiner(s): Wu, Daniel J.
• Application Number:
  US09/118,756
• Time in Patent Office: 550 Days
• Field of Search: 340/635, 340/664, 340/657, 340/691, 361/91-93, 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 contact closure and a light indication indicative thereof includes a rotatably mounted indicator flag. The flag is positioned in either a reset indicating or a fault indicating state by a four-pole magnetic pole piece, which is magnetized to an appropriate magnetic orientation by momentary application of a current to an actuator winding on the pole piece. A first magnetically actuated reed switch in an auxiliary magnetic circuit associated with a first pole of the magnetic pole piece and including the actuator winding and a first bias magnet 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. A second magnetically actuated reed switch associated with a second pole of the magnetic pole piece and including the actuator winding and a second bias magnet closes upon occurrence of the fault current for external signaling or control purposes.

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 first magnetic circuit including a first magnetic pole piece, a first magnetically actuated switch and a first 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 a reset indicating state in response to a magnetic field in said magnetic pole piece in said one direction and to a fault indicating state in response to a magnetic field in said magnetic pole piece in said other direction;

a second magnetic circuit including a second magnetic pole piece, a second magnetically actuated switch and a second 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 a reset indicating state in response to a magnetic field in said one direction and to a fault indicating state 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 magnetic pole pieces in a direction to condition said first and second magnetically actuated switches to said reset indicating states during normal current flow in the monitored conductor, and for developing a magnetic field in said pole pieces in said opposite direction to condition said first and second magnetically actuated switches to said fault indicating states upon occurrence of a fault current in the conductor; and

said first magnetically actuated switch connecting said battery to said lamp in said fault indicating state whereby said lamp lights in said fault indicating state; and

said second magnetically actuated switch being connected to an external indicating or control circuit for remote indication of said reset and fault indicating states.

2. A fault indicator as defined in claim 1 wherein said first and second magnetic pole pieces each include a pair of spaced-apart magnetic poles, and said magnetically actuated switches are disposed between said poles.

3. A fault indicator as defined in claim 2 wherein said magnetically actuated switches each include 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 switches each comprises a reed switch.

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

6. A fault indicator as defined in claim 5 wherein said first and second magnetic pole pieces are each 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 comprising an indicator flag viewable from the exterior of the housing and a first magnetic circuit including 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 second magnetic circuit including a second magnetic pole piece, a first magnetically actuated switch and a first bias magnet, said first 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 first magnetically actuated switch is actuated to a reset indicating state in response to a magnetic field in said second magnetic pole piece in said one direction and is actuated to a fault indicating state in response to a magnetic field in said second magnetic pole piece in said other direction;

a third magnetic circuit including a third magnetic pole piece, a second magnetically actuated switch and a second bias magnet, said second 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 to a reset-indicating state in response to a magnetic field in said third magnetic pole piece in said one direction and to a fault-indicating state in response to a magnetic field in said third magnetic pole piece in said other direction;

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

said first magnetically actuated switch connecting said battery to said lamp whereby said lamp lights when said first magnetically actuated switch is in said fault indicating state; and

said second magnetically actuated switch being connected to an external indicating or control circuit.

8. A fault indicator as defined in claim 7 wherein said second and third magnetic pole pieces each include a pair of spaced-apart magnetic poles, and said magnetically actuated switches are each disposed between said poles.

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

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

11. A fault indicator as defined in claim 10 wherein the axis of said reed switches are 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 first magnetically actuated switch;

a second magnetic pole piece having magnetic poles in magnetic communication with said first magnetically actuated switch, and a bias first 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 first magnetically actuated switch is actuated to a reset indicating state in response to a magnetic field in said one direction and is actuated to a fault indicating state in response to a magnetic field in said second magnetic pole piece in said other direction;

a second magnetically actuated switch;

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

circuit means including a magnetic actuator winding in magnetic communication with said first, second and third magnetic pole pieces for inducing magnetic fields 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 first magnetically actuated switch connecting said battery to said lamp whereby said lamp lights in said fault indicating state, and said second magnetically actuated switch being connected to an external indicating or control circuit.

13. A fault indicator as defined in claim 12 wherein said second and third magnetic pole pieces each include a pair of spaced-apart magnetic poles, and said magnetically actuated switches are each disposed between said poles.

14. A fault indicator as defined in claim 13 wherein said magnetically actuated switches each include 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 switches each comprise a reed switch.

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

17. A fault indicator as defined in claims 12 wherein said second and third magnetic pole pieces are generally U-shaped.

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