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WO1998001990A2 - Power supply system for telephone line wires - Google Patents

Power supply system for telephone line wires Download PDF

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Publication number
WO1998001990A2
WO1998001990A2 PCT/GB1997/001844 GB9701844W WO9801990A2 WO 1998001990 A2 WO1998001990 A2 WO 1998001990A2 GB 9701844 W GB9701844 W GB 9701844W WO 9801990 A2 WO9801990 A2 WO 9801990A2
Authority
WO
WIPO (PCT)
Prior art keywords
power supply
load
line
voltage
monitoring
Prior art date
Application number
PCT/GB1997/001844
Other languages
French (fr)
Other versions
WO1998001990A3 (en
Inventor
Francis Charles Hackett-Jones
Philip Rushton
Original Assignee
Telspec Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telspec Plc filed Critical Telspec Plc
Priority to AU34532/97A priority Critical patent/AU3453297A/en
Publication of WO1998001990A2 publication Critical patent/WO1998001990A2/en
Publication of WO1998001990A3 publication Critical patent/WO1998001990A3/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H04Q11/0435—Details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/001—Current supply source at the exchanger providing current to substations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M19/00—Current supply arrangements for telephone systems
    • H04M19/08—Current supply arrangements for telephone systems with current supply sources at the substations
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/1308—Power supply
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13216—Code signals, frame structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q2213/00—Indexing scheme relating to selecting arrangements in general and for multiplex systems
    • H04Q2213/13302—Magnetic elements

Definitions

  • This invention relates to a power supply system for telephone line wires .
  • the traditional telephone exchange battery for powering a handset at subscriber's premises has comprised a 50 volt DC power supply, this value having been chosen with a view to minimising stress on the copper telephone lines and to safety in the case of human contact with the wires.
  • a 50 volt DC power supply this value having been chosen with a view to minimising stress on the copper telephone lines and to safety in the case of human contact with the wires.
  • Recently, however the requirement for more efficient use of the telephone network has led to the introduction of line sharing systems wherein multiple subscribers are served by a single line.
  • To enable a corresponding number of telephone apparatus to be powered from the line it has been necessary to increase the power supplied to the line. This has hitherto been achieved by increasing the exchange battery voltage applied to the line whilst limiting the available current to maintain acceptable levels of safety.
  • This solution nevertheless increases stress on the copper line conductors, undesirably reducing their service life.
  • the invention provides a power supply system comprising a variable rate power supply, a load coupled to said power supply by a line the resistance of which is significant in relation to that of the load, monitoring means associated with said power supply for monitoring the voltage and/or current of the line circuit in the vicinity of the power supply, monitoring means for monitoring the voltage and/or current in the line circuit in the vicinity of the said load, telemetry means for transmitting output signals from the monitoring means associated with the load to receiving means in the vicinity of the power supply, and means associated with said power supply for for controlling the power delivered by the power supply in accordance with signals received from the respective monitoring means .
  • the line coupling the power supply to the load may be a conventional telephone line pair, or a single line feeding one or more circuits having an earth return.
  • the telephone line may serve as the medium for the transmission of the telemetry signals or the signals may be transmitted independently, for example by an associated optical fibre link for which a redundant telephone line serves only as a source of power.
  • the control of the power supply may serve one or more alternative purposes .
  • Monitoring only of the current flowing respectively at the power supply and load may be sufficient, for example, to determine leakage from the line and to enable the supply to be shut down for safety upon contact with the line. This may in turn enable the power supply equipment to have a higher permissible maximum current rating than would otherwise be considered safe.
  • the load may be in the form of a switch mode power supply the duty cycle of which varies in accordance with the number of subscribers being served at any given time. Variation of the resistance of the switch mode power supply as seen from the line will cause a corresponding variation in the voltage and current sensed in the vicinity of the load and thus the power supplied from the exchange battery can be varied accordingly.
  • an arrangement in accordance with the invention has the advantages that it can provide a maximum efficiency of power transfer under long line conditions; can provide only the amount of power required by the load, thus minimising voltage stress on the access network, and can provide safe operation at high terminal voltages without the need for arbitrary current limitation.
  • Fig 1 is a diagrammatic view of the basic system configuration
  • Fig 2 is a block schematic diagram showing the system in more detail.
  • Figure 1 shows the basic system configuration. It consists of five component parts, the load which is represented by a resistor, a variable voltage feed supply, a communication channel from the load to the feed supply, two line current monitors and a simulated line resistance.
  • the nominal value of load is designed such that it is equal to the line resistance. This ensures that for any given feed voltage the maximum power is supplied to the load. A voltage feed is used rather than a current because it results in a smaller change in power delivered to the load for any given resistive fault on the line.
  • the communication channel transmits the line current and the voltage across the load to the feed.
  • the purpose of the communication channel is to allow the load to demand only the necessary power from the exchange . As the system always operates at the maximum power transfer point the voltage on the line is kept to a minimum. This will reduce the effect of any electrolytic action on the copper pair and terminal blocks .
  • the exchange system knows the power that is fed to the line, the power used by the load and the power dissipated in the line, it is possible to detect any transient fault condition. Steady state line leakage conditions can also be monitored.
  • FIG 2 shows an example block schematic of the system.
  • the power feed and the load referred to in Figure 1 are now shown as the exchange and remote units respectively.
  • the exchange power feed consists of a dual output flyback switch mode supply.
  • the line voltage is fixed as symmetrical about earth.
  • Line current monitors are included for each wire and the results fed to the EU control circuit.
  • the transformers T2 and T3 provide the communication channel. This could use the 2B1Q basic rate ISDN line protocol. The voltage and current information would be transmitted using the spare bits in the EOC channel. It is not necessary to use this protocol, any appropriate system could be used provide that there is the spare bandwidth .
  • the remote power supply is also based upon a flyback switch mode configuration, however the primary and secondary sides are isolated.
  • a voltage and current monitor is provided on the primary side and opto couplers are used to feed the results to the RU controller.
  • the EU controller knows the voltage across the remote unit -and the feed voltage at the exchange. It adjusts the feed so that the remote voltage is nominally 60% of the exchange. This allows the remote to instantaneously draw more power from the line and give the exchange time to increase the feed to maintain the 60% ratio. If at any time the three line current monitors do not indicate the sam * value of current it can be assumed that a line fault exists. When th- fault condition arises slowly it will be due to l i ne leakage. A n appro ⁇ riate threshold can be set above which the system shuts down and raises an alarm. If the fault occurs quickly i t w i ll be due to a contact, such as a person touching the line. Under these conditions the system can immediately shut down mak i ng the system safe.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Devices For Supply Of Signal Current (AREA)

Abstract

A power supply system, more particularly for telephone lines, comprises a load coupled to the power supply by a line, for example a telephone line, the resistance of which is significant in relation to the resistance of the load. Monitoring means are provided in the vicinity of the power supply and in the vicinity of the load for monitoring the voltage and/or current in the line circuit. Telemetry means is provided for transmitting output signals from the monitoring means in the vicinity of the load to receiving means in the vicinity of the power supply. Means associated with the power supply is arranged to receive signals from the respective monitoring means and to control the power delivered by the power supply.

Description

POWER SUPPLY SYSTEM FOR TELEPHONE LINE WIRES
This invention relates to a power supply system for telephone line wires .
The traditional telephone exchange battery for powering a handset at subscriber's premises has comprised a 50 volt DC power supply, this value having been chosen with a view to minimising stress on the copper telephone lines and to safety in the case of human contact with the wires. Recently, however the requirement for more efficient use of the telephone network has led to the introduction of line sharing systems wherein multiple subscribers are served by a single line. To enable a corresponding number of telephone apparatus to be powered from the line, it has been necessary to increase the power supplied to the line. This has hitherto been achieved by increasing the exchange battery voltage applied to the line whilst limiting the available current to maintain acceptable levels of safety. This solution nevertheless increases stress on the copper line conductors, undesirably reducing their service life.
The same considerations may apply in cases where redundant telephone line wires are used only for power supply, for example to equipment handling signals transmitted by optical fibres that cannot carrry power.
It is accordingly an object of the invention to provide an improved system for transmittng power via telephone line wires .
The invention provides a power supply system comprising a variable rate power supply, a load coupled to said power supply by a line the resistance of which is significant in relation to that of the load, monitoring means associated with said power supply for monitoring the voltage and/or current of the line circuit in the vicinity of the power supply, monitoring means for monitoring the voltage and/or current in the line circuit in the vicinity of the said load, telemetry means for transmitting output signals from the monitoring means associated with the load to receiving means in the vicinity of the power supply, and means associated with said power supply for for controlling the power delivered by the power supply in accordance with signals received from the respective monitoring means .
The line coupling the power supply to the load may be a conventional telephone line pair, or a single line feeding one or more circuits having an earth return. The telephone line may serve as the medium for the transmission of the telemetry signals or the signals may be transmitted independently, for example by an associated optical fibre link for which a redundant telephone line serves only as a source of power.
The control of the power supply may serve one or more alternative purposes .
Monitoring only of the current flowing respectively at the power supply and load may be sufficient, for example, to determine leakage from the line and to enable the supply to be shut down for safety upon contact with the line. This may in turn enable the power supply equipment to have a higher permissible maximum current rating than would otherwise be considered safe.
Monitoring of both voltage and current may enable determination of the relative conditions of the line and load, for example enabling the power supply to be matched to the load without the need to take into consideration the line resistance. Where the line is fo supply a group of subscribers, the load may be in the form of a switch mode power supply the duty cycle of which varies in accordance with the number of subscribers being served at any given time. Variation of the resistance of the switch mode power supply as seen from the line will cause a corresponding variation in the voltage and current sensed in the vicinity of the load and thus the power supplied from the exchange battery can be varied accordingly.
In summary, an arrangement in accordance with the invention has the advantages that it can provide a maximum efficiency of power transfer under long line conditions; can provide only the amount of power required by the load, thus minimising voltage stress on the access network, and can provide safe operation at high terminal voltages without the need for arbitrary current limitation.
One embodiment of an arrangement in accordance with the invention is illustrated by way of example in the accompanying drawings, in which:
Fig 1 is a diagrammatic view of the basic system configuration, and
Fig 2 is a block schematic diagram showing the system in more detail.
Figure 1 shows the basic system configuration. It consists of five component parts, the load which is represented by a resistor, a variable voltage feed supply, a communication channel from the load to the feed supply, two line current monitors and a simulated line resistance.
The nominal value of load is designed such that it is equal to the line resistance. This ensures that for any given feed voltage the maximum power is supplied to the load. A voltage feed is used rather than a current because it results in a smaller change in power delivered to the load for any given resistive fault on the line. The communication channel transmits the line current and the voltage across the load to the feed.
The purpose of the communication channel is to allow the load to demand only the necessary power from the exchange . As the system always operates at the maximum power transfer point the voltage on the line is kept to a minimum. This will reduce the effect of any electrolytic action on the copper pair and terminal blocks .
As the exchange system knows the power that is fed to the line, the power used by the load and the power dissipated in the line, it is possible to detect any transient fault condition. Steady state line leakage conditions can also be monitored.
If a person should now make contact with the line some of the current from the feed will be taken away from the load. The system can sense this and shut down the feed supply making the system safe. In addition as the line voltage is always kept to a minimum it will inherently be safer than conventional systems.
Figure 2 shows an example block schematic of the system. The power feed and the load referred to in Figure 1 are now shown as the exchange and remote units respectively.
The exchange power feed consists of a dual output flyback switch mode supply. The line voltage is fixed as symmetrical about earth. Line current monitors are included for each wire and the results fed to the EU control circuit.
The transformers T2 and T3 provide the communication channel. This could use the 2B1Q basic rate ISDN line protocol. The voltage and current information would be transmitted using the spare bits in the EOC channel. It is not necessary to use this protocol, any appropriate system could be used provide that there is the spare bandwidth .
The remote power supply is also based upon a flyback switch mode configuration, however the primary and secondary sides are isolated. A voltage and current monitor is provided on the primary side and opto couplers are used to feed the results to the RU controller.
The EU controller knows the voltage across the remote unit -and the feed voltage at the exchange. It adjusts the feed so that the remote voltage is nominally 60% of the exchange. This allows the remote to instantaneously draw more power from the line and give the exchange time to increase the feed to maintain the 60% ratio. If at any time the three line current monitors do not indicate the sam* value of current it can be assumed that a line fault exists. When th- fault condition arises slowly it will be due to line leakage. An approπriate threshold can be set above which the system shuts down and raises an alarm. If the fault occurs quickly it will be due to a contact, such as a person touching the line. Under these conditions the system can immediately shut down making the system safe.

Claims

1. A power supply system comprising a variable power . supply, a load coupled to said power supply by a line the resistance of which is significant in relation to that of the load, monitoring means associated with said power supply for monitoring the voltage and/or current of the line circuit in the vicinity of the power supply, monitoring means for monitoring the voltage and/or current in the line circuit in the vicinity of the said load, telemetry means for transmitting output signals from the monitoring means associated with the load to receiving means in the vicinity of the power supply, and means associated with said power supply for controlling the power delivered by the power supply in' ccordance with signals received from the respective monitoring means
2. A system according to claim 1, in which the line coupling the power supply to the load is a telephone line pair.
3. A system according to claim 1 or 2, in which said telemetry means is coupled to said receiving means via said line.
4. A system according to any one of claims 1 to 3 , in which said monitoring means is arranged to monitor line current: in the vicinities of the power supply and the load.
3. A system according to claim 4, in which said monitoring means is further arranged to monitor voltage in the vicinity of the load.
6. A system according to claim 5, in which the said power supply is a variable voltage supply and incorporates voltage monitoring τιeans .
7. A system according to claim 6, in which the said control means is arranged to control the voltage of the said power supply in order to maintain a predetermined relationship between the voltages across the power supply and the load respectively. θ. A system according to claim 7, in which the said power supply is a switch mode power supply.
9. A system according to any one of claims 1 to 8, in which the said load comprises a switch mode power supply arranged to power a plurality of subscriber telephone line circuits.
10. A system according to claim 1, substantially as described herein.
PCT/GB1997/001844 1996-07-09 1997-07-09 Power supply system for telephone line wires WO1998001990A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU34532/97A AU3453297A (en) 1996-07-09 1997-07-09 Power supply system for telephone line wires

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9614401.9 1996-07-09
GB9614401A GB2315188B (en) 1996-07-09 1996-07-09 Power supply system for telephone line wires

Publications (2)

Publication Number Publication Date
WO1998001990A2 true WO1998001990A2 (en) 1998-01-15
WO1998001990A3 WO1998001990A3 (en) 1998-03-05

Family

ID=10796610

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/001844 WO1998001990A2 (en) 1996-07-09 1997-07-09 Power supply system for telephone line wires

Country Status (4)

Country Link
AU (1) AU3453297A (en)
GB (1) GB2315188B (en)
WO (1) WO1998001990A2 (en)
ZA (1) ZA966101B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7535966B2 (en) 2004-08-17 2009-05-19 Adaptive Spectrum And Signal Alignment, Inc. DSL data collection system

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2071461B (en) * 1980-02-14 1984-01-25 Standard Telephones Cables Ltd Telephone line feed
SE431704B (en) * 1982-07-06 1984-02-20 Ericsson Telefon Ab L M PROCEDURE FOR POWER SUPPLY OF A SUBSCRIBER DEVICE FROM A TELEPHONE SWITCH
US4808905A (en) * 1986-08-05 1989-02-28 Advanced Micro Devices, Inc. Current-limiting circuit
IT1197917B (en) * 1986-10-24 1988-12-21 Sgs Microelettronica Spa CONTROL CIRCUIT FOR A VOLTAGE REGULATOR OF A CIRCUIT INTERFACE CONNECTION USER TELEPHONE LINE (SLIC)
JPH0626358B2 (en) * 1989-08-11 1994-04-06 日本電気エンジニアリング株式会社 Power supply voltage control circuit
EP0446944A3 (en) * 1990-03-16 1991-12-27 Fujitsu Limited Feed circuit in exchanger
DE69120135T2 (en) * 1990-04-04 1997-01-23 Seiscor Tech Inc Interface circuit for subscriber line that supplies regulated electricity
JPH04157996A (en) * 1990-10-22 1992-05-29 Nec Corp Feeding system for key service unit
JPH05252286A (en) * 1992-03-03 1993-09-28 Matsushita Electric Ind Co Ltd Line terminal equipment

Also Published As

Publication number Publication date
GB2315188B (en) 1999-04-14
ZA966101B (en) 1998-03-03
WO1998001990A3 (en) 1998-03-05
GB9614401D0 (en) 1996-09-04
AU3453297A (en) 1998-02-02
GB2315188A (en) 1998-01-21

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