SIGNAL COUPLER

Abstract: The present invention relates to apparatus for coupling communications equipment to a conductor or cable. In particular, it relates to an "elbow" or "T" shaped type coupler. The present invention aims to provide a method and apparatus for effectively coupling communication signals onto and off an existing, possibly energised, distribution or transmission network. In a first aspect, the present invention provides a coupler including a pin (1, 20) for electrical connection to a socket, high pass filter means (5) electrically connected to the pin and connection means (7) for connecting the high pass filter means to a signal source. Preferably the pin (1, 20) is adapted or arranged so as to be suitable for connection to a socket (e.g. a primary terminal) of a transformer. In this way, a high frequency communication signal coupling may be made to the primary winding of the transformer without any need to interrupt the operation of the transformer or the power supply to consumers. Furthermore, the installation of the connection is safe and easy to do, which as will be appreciated, is important in high voltage equipment.

Description: SIGNAL COUPLER The present invention relates to apparatus for coupling communications equipment to a conductor or cable. In particular, it relates to an "elbow" or "T" shaped type coupler . Various published patent applications of the present applicant disclose systems whereby telecommunications signals can be conveyed along an electricity distribution and/or transmission network. These applications include the following; O94/09572, W095/29536, W095/29537, WO96/07245, 098/19398, the disclosures of which are incorporated herein by reference. In order to safely, efficiently and cost effectively couple communication signals onto power distribution and/or transmission networks it becomes desirable to consider not only the interconnecting device itself, and its component parts (e.g. a high pass filter), but also the ease with which such a device might be retro-fitted to an existing energised power distribution and/or transmission network. This becomes a more complex issue as the distribution and/or transmission network voltage increases. Furthermore, the actual location of such interface devices requires to be carefully considered m order to permit other associated functions, such as transformer by-pass, to be safely and cost effectively implemented as necessary. In some electricity distribution/transmission networks it is desirable to provide a communications signal bypass path so that the communication signal can be routed around the transformer, as a transformer may act as an attenuator for high frequency signals. In, for example, the USA it is common for pad (ground) mounted transformers to be used m electricity distribution and transmission networks. The primary windings of such transformers are often connected m a ring and, for this purpose, each transformer is usually provided with two primary winding connection terminals or sockets - m figure 4 these are labelled Hla and Hlb . The intention is that a high voltage cable may be connected to, for example, terminal Hla and then if a further connection onto another pad mount transformer is required, such connection can be made via a further lead connected to terminal Hlb. Obviously if no further connection is required then nothing will be connected to terminal Hlb . The high voltage connections to terminals Hla and Hlb are usually made by means of an elbow connector, as shown m figure 6. The connector consists of a resin filled elbow shaped package 60 protruding from one end of which is a probe or pm 62. This probe 62 locates inside socket Hla (for example) when connected to a transformer. Probe 62 is electrically connected via a connection 64 to a terminal 66. Terminal 66 is connected to a high voltage cable or conductor when m use. The present invention aims to provide a method and apparatus for effectively coupling communication signals onto and off an existing, possibly energised, distribution or transmission network. Accordingly, m a first aspect, the present invention provides a coupler including a pin for electrical connection to a socket, high pass filter means electrically connected to the pm and connection means for connecting the high pass filter means to a signal source. Preferably the pm is adapted or arranged so as to be suitable for connection to a socket (e.g. a primary terminal) of a transformer. Such a connector is suitable for use m situations where, for example, terminal Hlb as described above is not otherwise m use. In this way, a high frequency communication signal coupling may be made to the primary winding of the transformer without any need to interrupt the operation of the transformer or the power supply to consumers. Furthermore, the installation of the connection is safe and easy to do, which as will be appreciated, is important m high voltage equipment. However, as was explained above, the terminal Hlb (for example) may not always be free and will not be free if a number of transformers have been connected m a ring or a line. Accordingly, m a second aspect, the present invention provides a coupler including: a pm for electrical connection to a socket, a second socket electrically connected to the p and being adapted for receipt of a second pm of a further (e.g. high/medium voltage, low frequency) connector, high pass filter means electrically connected to the pm and connection means connected to the high pass filter means for receipt of a signal from a signal source. In this way, the connector may be formed in a "T" shaped package and can be interposed between a regular low voltage connector (e.g. an elbow shaped connector as shown in figure 6) and the input socket of, for example, a transformer. Again, this allows the coupling of communications equipment to the low voltage line in a safe and efficient manner. In particular, if a number of transformers are connected in a ring as described above, then this allows one of the connectors (e.g. attached to terminal Hlb as described above) to be disconnected without any interruption to the consumers' electricity supply and for the "T" shaped connector then to be connected safely. Preferably the coupler of either of the above aspects is arranged in a standard "elbow" or "T" shaped configuration so as to fit standard sockets on transformers. Preferably the coupler also includes a fuse which may be located between the high pass filter means and the pin. The high pass filter means may be provided by a capacitor and also included may be a protective balun and/or isolation transformer. The whole connector package may be filled with a suitable insulative resin and/or oil or other suitable insulative medium, preferably with adequate stress relief capabilities . In a further aspect, the present invention provides a method of coupling a communication signal to an electricity network and/or bypassing a transformer of the network using the apparatus as described above. A signal cable may be coupled to the signal source connector of the coupler which turn may be connected to an amplifier and/or signal regenerator (could be analogue or digital) and/or modem device, and/or remodulator. This m turn may be connected to a further low voltage coupler which is then connected to one or more of the terminals of the secondary of the transformer. Embodiments of the present invention will now be described with reference to the accompanying drawings which : - Figure 1 shows a coupler according to a first embodiment of the present invention. Figure 2 shows a coupler according to a second embodiment of the present invention. Figure 3 is a schematic circuit diagram of the coupler according to an embodiment of the present invention. Figure 4 shows a typical pad mount transformer with couplers according to embodiments of the present invention being used. Figure 5 is a schematic diagram of a bypass system for a transformer according to an embodiment of the present invention . Figure 6 is a schematic diagram of a prior art low voltage coupler. Figure 1 shows a coupler according to the first embodiment of the present invention. The coupler is included m a typical elbow connector profile package such as might be obtained from Elastimold (TM) , for example their 160 series. Such connectors are utilised, particularly the USA, to connect underground single phase medium voltage (e.g. 13.8kv) distributor cables to the primary connections of a pad mount transformer such as that shown in figure 4. The coupler includes a medium voltage probe 1 encased m a housing 3 which has been filled with an insulative resin 2 and/or stress relieving rubber. The probe 1 is connected to a fuse 4 which m turn is connected to a meαium voltage capacitor (e.g. 0.01 microfarads) which acts as a high pass filter for the communication signals. The capacitor 5 is connected to a balun and/or isolation transformer 6 which provides a protective coupling for high frequency communication signals. The transformer 6 is m turn connected to a connector 7 which may, m use, be connected to a signal source (not shown) . As is explained above, such a- coupler may be used to couple to an unused primary winding terminal (e.g. Hlb m figure 4) of a pad mount transformer. Figure 2 shows a coupler according to a second embodiment of the present invention. The coupler includes a pm 20 which, as for the embodiment of figure 1, is dimensioned so as to fit into a standard high voltage socket of e.g. a pad mount transformer as shown m figure 4. The pm 20 is again connected to a fuse 21, capacitor 22, balun/isolation transformer 23 and connected 24 m the same way as the embodiment of figure 1. However, the difference lies m the inclusion of a p socket 25 which is electrically connected to pm 20 and is m line with pm 20 m the upper arm of the "T" shaped coupler package. Socket 25 is dimensioned so as to receive a pm (which will be similar dimensions to pin 20) from a standard low voltage coupler such as that shown in figure 6. In this way, a prior art coupler such as shown in figure 6 can be "piggy-backed" onto the coupler of figure 2 which in turn is connected to a socket of a transformer. This permits the coupler of figure 2 to be connected to transformers such as that shown in figure 4 where both terminals Hla and Hlb are already in use. A schematic diagram of the electrical circuit of the couplers of figures 1 and 2 is shown in figure 3. A fuse link 30 is shown connected respectively to a transformer bus bar 31 and a capacitor 32. As before, the capacitor 32 is connected to a balun and/or isolation transformer (or other suitable transformer) 33, one winding of which is connected to a signal source 34. The secondary winding of the balun transformer terminates in a suitable high frequency connector (e.g. a BNC connector) and a safety earth bonding strap 35 is also provided. Figure 4 illustrates a pad mount transformer as utilised in a typical North American underground power distribution network. The transformer includes primary winding terminals Hla and Hlb and also secondary winding terminals XI, X2 and X3. A medium voltage high frequency coupler (such as the embodiment of figure 1) 40 is connected to terminal Hlb and from the coupler 40 a connection 42 may be made to high frequency communication signal apparatus. Also shown are a number of earth connections 44 for the various couplers and also for the secondary winding socket X2. Figure 5 is a schematic diagram of a transformer bypass which could be used with, for example, the transformer of figure 4. A "T" shaped connector 50, such as that of the embodiment of figure 2, is "piggy-backed" with a normal low voltage connector 52 and both of these are connected to a primary winding terminal Hla. Communication signals may be propagated along the cable or conductor 51 as has been described previous published patent applications by the present applicant. The communication signals may be removed from cable 51 using coupler 50 and then passed through an optional amplifier or signal regenerator 53. The signals can then be passed to a low voltage coupler 54 which m turn connects the signals to one or more of the secondary winding terminals XI, X2 and X3. The signals are then propagated on the low voltage network (LV) . 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: CLAIMS 1. A coupler including a pin for electrical connection to a socket, the pin being adapted or arranged so as to be suitable for connection to a socket of a transformer, high pass filter means electrically connected to the pin and connection means for connecting the high pass filer means to a signal source. 2. A coupler according to claim 1 including a second socket electrically connected to the pin and being adapted for receipt of a second pin of a further connector . 3. A coupler according to claim 1 or claim 2 arranged in a standard "elbow" or "T" shaped configuration. 4. A coupler according to any of the above claims including a fuse located between the high pass filter means and the pin. 5. A coupler according to any one of the above claims wherein the high pass filter means includes a capacitor. 6. A coupler according to any one of the above claims including a protective balun and/or isolation transformer . 7. A method of coupling a communication signal to an electricity network and/or bypassing a transformer of the network using the apparatus of any of the above claims. 8. A method according to claim 7 in which the high frequency communication signal coupling is made to the primary winding of the transformer without any interruption in the operation of the transformer or the power supply to consumers . 9. A method according to claim 7 or claim 8 wherein, if a number of transformers are connected in a ring one of the connectors is disconnected.

Inventors: BROWN PAUL ANTHONY, DICKINSON JOHN, BROWN, PAUL, ANTHONY, DICKINSON, JOHN
Applicants: BROWN PAUL ANTHONY, DICKINSON JOHN, NOR WEB DPL LIMITED, BROWN, PAUL, ANTHONY, DICKINSON, JOHN, NOR.WEB DPL LIMITED
Application year: 2000
Main classification: H01R13
IPC codes: H01H85, H01R13