CABLING APPARATUS FOR HIGH-RESISTANCE APPLICATIONS

Abstract

A telecommunications cable for making high resistance measurements comprising a plurality of bundles, each comprising a twisted pair of Category 6a copper conductors and a metal foil shield, one of said copper conductors in each twisted pair serving as a signal wire and the other of said copper conductors in each twisted pair being grounded to thereby serve as a noise ground, a braided grounded metal sheath surrounding said plurality of bundles of twisted pairs; and a grounded shield used as an outer sleeve, whereby said cable is triple grounded.

Claims

1. A telecommunications cable for making high resistance measurements comprising a. a plurality of bundles, each comprising a twisted pair of Category 6a copper conductors and a metal foil shield, one of said copper conductors in each twisted pair serving as a signal wire and the other of said copper conductors in each twisted pair being grounded to thereby serve as a noise ground; b. a grounded metal sheath surrounding said plurality of bundles of twisted pairs; and c. an outer sleeve, whereby said cable is triple grounded.

2. A telecommunications cable according to claim 1, wherein: a. said signal wire provides signal continuity and said copper conductor which is grounded functions as a grounded shield, and b. the internal ground shield inside the category 6a wire bundle functions as an additional ground shield within the pair of category 6a wire bundles.

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. A telecommunications cable according to claim 1, wherein said outer sleeve comprises PTFE, nylon, polyethylene, PVS, PET, PEEK, ABS, or polypropylene.

10. A telecommunications cable according to claim 1, comprising four of said bundles.

11. A telecommunications cable according to claim 2, wherein said outer sleeve comprises PTFE, nylon, polyethylene, PVS, PET, PEEK, ABS, or polypropylene.

12. A telecommunications cable according to claim 2, comprising four of said bundles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a longitudinal cross-section of a typical triaxial cable; and

[0007] FIG. 2 is a transverse cross section of a cable assembly of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The invention is a telecommunications cable for making high resistance measurements comprising a plurality of bundles, each comprising a twisted pair of category 6a copper conductors and a metal foil shield, one of said copper conductors in each twisted pair serving as a signal wire and the other of said copper conductors in each twisted pair being grounded to thereby serve as a noise ground; a braided grounded metal sheath surrounding said plurality of bundles of twisted pairs, and a grounded shield used as an outer sleeve, whereby said cable is triple grounded.

[0009] FIG. 2 shows a cable assembly comprising a plurality of Cat 6a twisted pair cables 10. When utilized in our present invention one wire 12 of each pair of wires in the twisted pair is utilized as a current signal. The other wire 14 in the pair is connected to the same ground potential as the meter. The Cat 6a standard has the pairs of wires twisted in such a way to minimize noise and crosstalk between the two. Each wire of the twisted pair 10 is surrounded by insulation 20. By grounding the other wire it serves essentially as a shield. The drain wire 16 which is connected to the aluminum foil shield 18 serves as a secondary shield and is connected to the meter ground as well. In order to get the appropriate low leakage current connection needed a second Cat 6a cable is used in the identical way. These two Cat 6a cables are then placed in a standard braided metal cable management sheath. This metal sheath is connected to the meter ground. In order to take measurements, such as SIR measurements where there are many measurements to be made, one of the two Cat 6a cables provides the positive voltage, and the other provides the negative. The meter can then switch between the appropriate pairs of wire. FIG. 2 shows a core 22 of four pairs cabled together. The cable is surrounded by a jacket 24. The outer jacket or outer sleeve 24 is made of PTFE, nylon polyethylene, PVS, PET, PEEK, ABS, or polypropylene.

[0010] This configuration reduces alien crosstalk which is the interference caused by adjacent conductors in a cable. Alien crosstalk is a combination of two components: alien Near-End CrossTalk (NEXT) and alien Far End CrossTalk (FEXT). These are types of noise that gets capacitively coupled into the current signal. The amount of noise in these situations is proportional to the:

[0011] Inverse distance from each signal wire;

[0012] Length (technically impedance) of the wire;

[0013] Frequency;

Amplitude.

[0014] The present cabling apparatus mitigates these by four main methods:

[0015] Shielding of the signal wire (provided by the aluminum foil shield in Cat 6a and many other telecommunications cables)

[0016] Separating the signal from the source. This is provided by using two Cat 6a cables;

[0017] Reducing the amplitude of the noise. This is achieved by grounding one conductor of each twisted pair. This provides a low impedance path for alien crosstalk to flow;

[0018] By using a twisted pair, the induced noise is canceled out as each wire's induced current induces a counter current in the other.

[0019] The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings.

[0020] The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.