EP1173901A1

EP1173901A1 - Coupling apparatus and method

Info

Publication number: EP1173901A1
Application number: EP00914274A
Authority: EP
Inventors: Paul Anthony Brown; Brian Summerscales
Original assignee: Nor Web DPL Ltd
Current assignee: Nor Web DPL Ltd
Priority date: 1999-04-01
Filing date: 2000-03-29
Publication date: 2002-01-23
Also published as: AU3567000A; NZ514880A; JP2002541638A; CA2368443A1; WO2000060701A1; GB0124697D0; GB2363529A; HK1043484A1

Abstract

The present invention relates to coupling apparatus for fitting to a conductor or cable. In particular, it refers to high frequency coupling apparatus suitable for telecommunications signals propagated, at least in part, along conventional power distribution cables. Accordingly, in a first aspect, the present invention provides a coupling apparatus suitable for coupling with an electricity cable (2), where the cable includes an electrically insulated conducting member (1), where the coupling apparatus includes cable insulation penetration means (3) for penetrating the electricity cable to provide an electrical connection to the conducting member, the penetration means (3) being electrically connected to a coupling member (5) suitable for connection to a telecommunications signal source or receiver. In this way, a coupling member suitable for connection to a telecommunications signal source or receiver may be electrically connected to the conducting core of a power cable or other type of conductor.

Description

COUPLING APPARATUS AND METHOD

The present invention relates to coupling apparatus for

fitting to a conductor or cable. In particular, it

refers to high frequency coupling apparatus suitable for

telecommunications signals propagated, at least in part,

along conventional power distribution cables.

The transfer of communication signals along electricity

distribution and/or transmission networks is a promising

development in the telecommunications industry. The

communication signals may be transferred even whilst the

power cables/conductors are energized.

Various technical aspects of systems whereby

telecommunications signals can be conveyed along an

electricity distribution and/or transmission network are

disclosed in published patent applications of the present

applicant. These applications include the following:

O94/09572, W095/29572, 095/29537, WO96/07245,

W098/19398, the disclosures of which are incorporated

herein by reference. It is desirable that the coupling of telecommunication

signals onto power distribution and/or transmission

networks be achieved in a safe, efficient and cost-

effective way.

The present invention aims to provide a method and

apparatus for effectively coupling communication signals

onto and off an existing, possibly energized, mains

electricity distribution and/or transmission network.

Accordingly, in a first aspect, the present invention

provides a coupling apparatus suitable for coupling with

an electricity cable, where the cable includes an

electrically insulated conducting member, where the

coupling apparatus includes cable insulation penetration

means for penetrating the electricity cable to provide an

electrical connection to the conducting member, the

penetration means being electrically connected to a

coupling member suitable for connection to a

telecommunications signal source or receiver.

In this way, a coupling member suitable for connection to a telecommunications signal source or receiver may be

electrically connected to the conducting core of a power

cable or other type of conductor.

Thus the coupling device could be retro-fitted to an

existing power distribution and/or transmission network.

To minimize disruption to consumers' power supplies and

to avoid time-consuming installation, preferably the

coupling device should be adapted to be fitted to, for

example, an insulated power cable without disconnecting

that power cable from the power source, i.e. while the

cable is "energized" or live.

The coupling member is electrically isolated at low

frequencies (e.g. 50/60 Hz or possibly up to 100 or 200

Hz) from the insulation penetration means using a low

frequency protection means such as a high pass filter,

for example a suitable capacitor. Furthermore, the

coupling member may be electrically protected from the

cable insulation protection means by, for example a fuse

and/or transformer, e.g. a balun transformer. The insulation penetration means is adapted to pierce a

sleeve of electrical insulation material around the power

cable or conductor and hence come into and establish

electrical contact with the electrical current carrying

part of the conductor. In this way, the coupling device

is suitable for attachment to a power cable or conductor

at many different places along the cable or conductor

length.

In some instances, it might not be desirable for the

electronic components to be attached to the cable at all

times. Accordingly, in a second aspect, the present

invention provides a coupling device including a clamp

and a clamp head. The clamp includes the insulation

penetration means and means for fitting the insulation

penetration means to the cable. The clamp head includes

a coupling member suitable for connection to a

telecommunications signal source or receiver. The

coupling member is preferably protected by low frequency

protection means such as a high pass filter, for example

a suitable capacitor. Furthermore, the coupling member

may be electrically protected from the cable insulation penetration means by, for example, a fuse and/or balun

transformer .

In a preferred embodiment of the present invention, one

end of the primary winding and/or one end of the

secondary winding of the transformer is/are electrically

bonded to an earth potential. Furthermore, in another

preferred embodiment, one end of both the primary and

secondary windings of the transformer are electrically

bonded to the same earth potential.

In another preferred embodiment of the present invention,

the cable insulation means includes a spike.

Additionally or alternatively, this spike may be rigid.

Additionally or alternatively, the spike may be

electrically conducting. Additionally or alternatively,

there may be a plurality of spikes, preferably spaced 0.5

- 1.5cm apart, most preferably around 1cm apart.

Preferably, the present invention includes clamping means

for urging the penetration means into the cable the

clamping means may include a screw operated compression member .

Preferably, the present invention includes a housing

which, in use, fits around the cable.

In another preferred embodiment of the present invention,

the coupling apparatus includes a two part housing, the

first part containing the coupling member and the second

part containing the penetration means wherein the two

parts are releasably joined together. Preferably, the

clamping means is included in the second part of the

housing.

Preferably, the cable insulation penetration means and

the coupling member are electrically connected via a

conducting spring.

Embodiments of the present invention will now be

described with reference to the accompanying drawings in

which: -

Figure 1 is a schematic diagram of a coupling device according to a first embodiment in which the main

internal components are illustrated.

Figure 2 is an exploded schematic diagram of a coupling

device according to the first embodiment, showing the

device in its two main component pieces.

Figure 3 is an exploded schematic diagram of a coupling

device according to the first embodiment, corresponding

to a section viewed in a plane which is perpendicular to

the axis of the cable at the line marked "X-X" in Figure

2.

Figure 4 is a schematic diagram of a coupling device

according to a second embodiment in which the main

internal components are illustrated.

Figure 5 is an exploded schematic diagram of a coupling

device according to the second embodiment, showing the

device in its three main component pieces.

Figure 6a is a side view of a coupling device according to a further embodiment of the present invention;

Figure 6b is an end view of the device of Figure 6a;

Figure 7a is a side view of a further embodiment of a

coupling device according to the present invention; and

Figure 7b is an end view of the device of Figure 7a.

Figures 1, 2 and 3 show a coupling device according to

the first embodiment of the present invention. The unit

consists of two parts 21 and 22, constructed in part

using a strong, non-conducting material, which are

clamped tightly together using, for example, two screws

7. The device is preferably clamped across an insulated

power cable 2. The outline of the unit is preferably

shaped to fit an insulated cable 2 between the two parts

of the coupling device 21 and 22. For example, the

outline of the coupling device is concave, as shown in

Figure 3. The insulation penetration means preferably

includes a rigid conducting spike 3. This spike

protrudes a pre-set distance into the concave outline of the unit. The insulation 8 is pierced and electrical

contact is made between the rigid conducting spike 3 and

the metallic power conductor 1 as the clamping screws 7

are tightened.

The rigid conducting spike 3 is electrically connected to

a circuit 4, schematically shown in Figure 1. This

circuit preferentially includes one or more protection

devices such as a fuse and a balun transformer. _The

circuit further includes a low frequency protection

device such as a high pass filter for the high frequency

communication signals, for example a suitable capacitor.

The circuit is provided with a coupling member such as a

communications signal input/output port, typically a

coaxial, unbalanced, high frequency, standard BNC

connector 5 well known in the art. Preferably, a safety

earth is attached via 6 in Figure 1. Additionally or

alternatively an isolation capacitor may be included on

the "braid" side of the coaxial connector 5 in order to

isolate it from the mains electricity supply in the event

of a fault. In this first embodiment, the circuit 4 is entirely

contained within the insulating casing of the device.

Therefore, during installation of the coupling device, no

^λ live' conducting elements are exposed, either on the

cable or on the device itself.

Figures 4 and 5 illustrate a coupling device according to

a second embodiment of the present invention. The device

is constructed in part using a strong^ non-conducting

material and is made up of three main parts 51, 52 and

53. Main parts 51 and 52 are shaped, for example in a

concave sense, so that an insulated cable 31 may fit

between them in a similar sense to the first embodiment,

shown in Figure 3. Parts 51 and 52 may be clamped

tightly together using a single screw 40. A rigid

conducting spike 34, similar to a spike 3 in the first

embodiment, protrudes a pre-set distance into the concave

outline of part 52. The insulation 42 is pierced and

electrical contact is made between the rigid conducting

spike 34 and the metallic power conductor 32 as the

clamping screw 40 is tightened. The rigid conducting spike may be electrically connected

to a fuse carrier and link 36 via a conducting spring 35

when the clamp 33, made up using main parts 51 and 52, is

attached to a clamp head 37 (or 53) via screws 41. The

clamp head contains a circuit 36, preferentially

including protection devices such as a fuse and a balun

transformer. The circuit further includes a low

frequency protection device such as a high pass filter

for high frequency communication signals and is similar

to the circuit 4 described in outline in the first

embodiment of the invention. The circuit 36 is provided

with a coupling member such as a communications signal

input/output port, typically a coaxial, unbalanced, high

frequency, standard BNC connector 38 well known in the

art. Preferably, a safety earth is attached via 39.

The second embodiment of the present invention allows the

clamp head 53 to be easily removed from the cable clamp

51 and 52 whilst, if desired, leaving the cable clamp 51

and 52 still attached to the cable. The cable clamp may

then be covered using a fascia plate. This removes the

need to place an insulating sleeve over the puncture hole in the cable insulation if it is required to remove the

coupling device from the cable at some later date.

The embodiment of the invention shown in Figures 6a and

6b consists principally of a first part 60 of the

coupling unit and a saddle 61. As will be seen, the

saddle 61 sits on top of the coupling unit part 60. The

saddle may, for example, be made of steel and may be

around 20 x 30 x 3mm in size including a tapped hole for

receipt of a screw 62, with for example a 5mm thread.

In use, the unit 60 is placed against an insulated cable

63 to a conductor of which contact is required to be

made. Initially, the saddle lies against or adjacent the

top of the part 60 as shown in Figure 6a. The contacts

(not shown) project against the cable 63.

One or more cable ties 64 (in this embodiment, two ties

are used) secure the unit 60 against the cable 63. In

this embodiment each of the cable ties 64 is located on

a respective side of the screw 62 and also serve to hold

the saddle against the unit 60. As will be seen more clearly m Figure 6b, the eye 65 of each cable tie abuts

against a square edge 66 of the saddle 61. By contrast,

the edge 67 of the saddle 61 over which the elongate

portion of the cable tie 64 lies is rounded so as to

relieve the stress on the cable tie. Also optionally

provided are locating notches in the saddle 61 (not

shown) which serve to locate the elongate portion of the

cable ties 64. In some embodiments, the rounded edges

mentioned previously may only be provided in the locating

notches.

Once the cable ties have been tightened as much as

possible by hand in the conventional manner, the machine

screw 62 may then be operated (in this case turned

clockwise) so that its end moves against the top of the

unit 60 and forces the saddle 61 away from the unit 60.

This action serves to drive the electrical connection

spikes through the installation cable 63. As will be

apparent to the skilled person, means other than the

screw 62 may be provided to perform this same function.

Figures 7a and 7b show a further embodiment of the present invention which is similar to the embodiment of

Figures 6a and 6b with the exception that the saddle is

omitted. The cable tie locating notches may instead be

formed directly in an upper edge 70 of the unit 71.

Means are provided inside the unit 71 (not shown) for

moving the tips of the electrical connection spikes in a

direction away from the unit 71 so that, in use, the

spikes extend further towards the cable 72. These means

are operable by, in this example, rotation of a rod head

73 which is located on the top surface of the unit 71.

Naturally other means for operating the spike driving

means will be apparent to the skilled person and may be

used instead.

In use, the unit 71 is placed adjacent the cable 72 and

the cable ties 74 are tightened by hand as previously.

The rod 73 (which may be made of nylon of, for example a

millimetre diameter) is then operated (e.g. turned

clockwise) to drive the contact spike (s) out of the base

of the coupler into the cable thereby tensioning the

cable ties and piercing the cable insulation to make

contact with the conductor. In either of the embodiments of Figure 6 or Figure 7, or

indeed in any of the embodiments described previously,

the base 68, 78 of the unit 60, 71 may be shaped

differently to that shown in the drawings. In a

preferred embodiment, the base 68, 78 may be shaped so as

to conform more closely to the surface shape of the cable

which, in this example, is roughly circular. This

enables the unit 60, 71 to be more easily located against

the cable.

Each of the embodiments of the present invention

described above may be self supporting in that they are

supported only by the cable to which they are clamped.

A further embodiment of the invention includes having one

or more lugs attached to the clamp devices. In this way,

the clamps themselves may be attached to a suitable

surface.

Furthermore, the embodiments described above are also

suitable for coupling communications signals to/from

cables with more than one conducting core. In this way,

a range of, for example differential, phase to phase, phase to neutral/earth, phase to earth, neutral to earth

or polyphase modes of high frequency signal coupling may

be provided.

As will be appreciated, the above embodiments are given

by way of example only and modifications will be apparent

to those skilled in the art.

Claims

1. A coupling apparatus suitable for coupling with an

electricity cable, where the cable includes an

electrically insulated conducting member, where the

coupling apparatus includes cable insulation

penetration means for penetrating the electricity

cable to provide an electrical connection to the

conducting member, the penetration means being

electrically connected to a coupling member suitable

for connection to a telecommunications signal source

or receiver.

2. A coupling apparatus according to any one of the

above claims including a clamp and a clamp head,

wherein the clamp includes the insulation

penetration means and means for fitting the

insulation penetration means to the cable, and the

clamp head includes the coupling member.

3. A coupling apparatus according to claim 1 including

low frequency protection means for electrically isolating the coupling member at low frequencies

from the insulation penetration means.

4. A coupling apparatus according to claim 1 or claim

2 including a fuse and/or transformer by which the

coupling member may be electrically protected from

the cable insulation protection means.

5. A coupling apparatus according to claim 4 in which

one end of the primary winding and/or one end of the

secondary winding of the transformer is/are

electrically bonded to an earth potential.

6. A coupling according to claim 5 in which one end of

both the primary and secondary windings of the

transformer are electrically bonded to the same

earth potential.

7. A coupling apparatus according to any one of the

above claims wherein the cable insulation means

includes a spike.

8. A coupling apparatus according to any one of the

above claims including clamping means for urging the

penetration means into the cable.

9. A coupling apparatus according to any one of the

above claims including a housing which, in use, fits

around the cable.

10. A coupling apparatus according to any one of the

above claims wherein the cable insulation

penetration means and the coupling member are

electrically connected via a conducting spring.