Neutral fault current detection device

Patent metadata

Field	Value
Publication number	US-9910078-B2
Application number	US-201514607852-A
Country	US
Kind code	B2
Filing date	Jan 28, 2015
Priority date	Jan 28, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A passive neutral fault current detection device fastened to cable television equipment detects the presence of a neutral fault within a subscriber's premises when the outer conductor of the coaxial cable is electrically bonded to the neutral conductor of the premises electrical service ground. In one example, the passive neutral fault current detection device employs a transformer circuit. The braided outer conductor of the coax cable acts as the primary coil of the transformer, and windings surrounding the coax cable act as a secondary coil. The windings are connected to an alert device to complete the circuit. As alternating current from a neutral fault flows through the braided sheath, a varying magnetic field is generated and impinges upon the secondary winding, which induces a varying voltage in the secondary winding. The voltage can drive the alert device which, in one embodiment, is a light emitting diode (LED).

First claim

The following is claimed:

1. In a multichannel data network comprising a cable television device configured to be operatively coupled to a coaxial cable at a point of demarcation, wherein the cable television device is configured to provide a bonded ground path from a ground path conductor element of the coaxial cable to a neutral conductor of an electrical service ground connection, a neutral fault current detection device configured to detect an alternating current in the ground path conductor element of the coaxial cable, the neutral fault current detection device comprising:
a coupling element configured to be coupled to the ground path conductor element of the coaxial cable;
a passive current sensing circuit configured to be coupled to the coupling element, the passive current sensing circuit being configured to detect a neutral fault current flow in the ground path conductor element of the coaxial cable that exceeds a threshold level when the coupling element is coupled to the ground path conductor element; and
a passive neutral fault alert device configured to be coupled to the current sensing circuit, and generate a neutral fault condition alert when the current sensing circuit detects that the neutral fault current flow in the ground path conductor element of the coaxial cable exceeds the threshold level;
wherein the passive current sensing circuit comprises a transformer circuit including a secondary transformer coil configured to be coupled to a primary transformer coil, the primary transformer coil being a braided sheath of an outer conductor of the coaxial cable;
wherein the coupling element is configured to provide current flow sufficient to power the passive sensing circuit when the neutral fault current flow exceeds the threshold level;
wherein the passive current sensing circuit is powered only by the detected neutral fault current flow in the ground path conductor element of the coaxial cable; and
wherein the neutral fault alert device is powered only by the detected neutral fault current flow in the ground path conductor element of the coaxial cable, and only after the neutral fault current flow exceeds the threshold level.

2. The neutral fault current detection device of claim 1 , wherein the cable television device is a ground block.

3. The neutral fault current detection device of claim 1 , wherein the cable television device is configured to be operatively coupled to the coaxial cable at a point downstream of the point of demarcation.

4. The neutral fault current detection device of claim 1 , wherein the coupling element is configured to couple with the ground path conductor element at a location between a distribution box within the multichannel data network and a subscriber's ground block.

5. The neutral fault current detection device of claim 1 , wherein the ground path comprises a ground wire connecting the outer conductor of the coaxial cable to an electrical service ground connection, the coupling element being configured to couple with the ground path conductor element at a location on the ground path.

6. The neutral fault current detection device of claim 1 , wherein the coupling element is configured to couple with the electrical service ground connection.

7. The neutral fault current detection device of claim 1 , wherein the neutral fault alert device is a light generator configured to display a lighting sequence associated with the severity of current flow.

8. The neutral fault current detection device of claim 7 , wherein the neutral fault alert device comprises a light emitting diode.

9. The neutral fault current detection device of claim 1 , wherein the neutral fault alert device is a sound generator that produces an audible alarm tone when the current flow in the ground path conductor element exceeds the threshold level.

10. A neutral fault current detection device configured to detect the presence of electrical current in a ground path of a coaxial cable in a multichannel data network, the current detection device comprising:
a passive current sensing circuit configured to sense current flow in a ground path conductor element of the coaxial cable;
a coupling element coupled to the passive current sensing circuit, the coupling element being configured to engage the ground path conductor element of the coaxial cable; and
a neutral fault alert device coupled to the passive current sensing circuit, the signaling device being configured to provide an alert when the current flow in only the ground path conductor element of the coaxial cable exceeds a threshold level;
wherein the passive current sensing circuit is powered by the current flow in only the ground path conductor element of the coaxial cable by way of the coupling element after the current flow in only the ground path conductor element of the coaxial cable exceeds the threshold level.

11. The neutral fault current detection device of claim 10 , wherein the neutral fault alert device comprises a powered circuit, and the passive current sensing circuit is configured to trigger the powered circuit when the current flow in only the ground path conductor element exceeds the threshold level.

12. The neutral fault current detection device of claim 11 , wherein the powered circuit comprises a battery power source.

13. The neutral fault current detection device of claim 10 , further comprising a transmitter configured to send a message upstream, through the multichannel data network, when the neutral fault alert device provides an alert.

14. In a multichannel data network comprising a cable television device configured to be operatively coupled to a coaxial cable at a point of demarcation, wherein the cable television device is configured to provide a bonded ground path from a ground path conductor element of the coaxial cable to a neutral conductor of an electrical service ground connection, a neutral fault current detection device configured to detect an alternating current in the ground path conductor element of the coaxial cable, the neutral fault current detection device comprising:
a coupling element configured to couple with the ground path conductor element of the coaxial cable;
a passive current sensing circuit configured to be coupled to the coupling element, the passive current sensing circuit being configured to detect a neutral fault current flow condition in only the ground path conductor element of the coaxial cable when the coupling element is positioned to engage the ground path conductor element of the coaxial cable; and
a neutral fault alert device configured to be coupled to the current sensing circuit, the neutral fault alert device being configured to generate a neutral fault condition alert when the current sensing circuit detects the neutral fault current flow condition only in the ground path conductor element of the coaxial cable;
wherein the passive current sensing circuit is powered by only the detected neutral fault current flow condition in the ground path conductor element of the coaxial cable by way of the coupling element after the neutral fault current flow condition in only the ground path conductor element of the coaxial cable is reached.

15. The neutral fault current detection device of claim 14 , wherein the neutral fault alert device is powered by the detected neutral fault current flow condition in only the ground path conductor element of the coaxial cable.

16. The neutral fault current detection device of claim 14 , wherein the passive current sensing circuit generates a trigger to power the neutral fault condition alert by a battery.

17. The neutral

Assignees

• Ppc Broadband Inc

Inventors

• Lawrence Michael E
• Palinkas Raymond W

Classifications

• G01R31/025 Primary

  Physics · mapped topic

• G01R31/52 Primary

  Testing for short-circuits, leakage current or ground faults · CPC title