WO1997008714A2

WO1997008714A2 - The control of current-carrying conductors

Info

Publication number: WO1997008714A2
Application number: PCT/US1996/013180
Authority: WO
Inventors: Michael Frederick Johnson; Louis-Andre Primic
Original assignee: Handelman, Joseph, H.
Priority date: 1995-08-15
Filing date: 1996-08-14
Publication date: 1997-03-06
Also published as: AU6774496A; WO1997008714A3

Abstract

Equipment (10) for controlling a plurality of current-carrying wires (12) includes a control device (26) which is connected intermediate terminals (18, 20) and (22) of an energiser (16) and wires (12) of an electric fence (14). The control device (26) further includes a monitor (36) resistor (34) in which each wire (12) terminates. The monitor (36) control operation of its associated switch (28) for connecting and disconnecting the wire (12) to the energiser (16).

Description

THE CONTROL OF CURRENT-CARRYING CONDUCTORS

THIS INVENTION relates to the control of current-carrying conductors. More particularly, the invention relates to a method of, and equipment for, controlling a plurality of current-carrying conductors.

The invention has particular application in the control of current-carrying conductors of electrified fences, either where a plurality of current- carrying conductors is arranged in parallel spaced relationship with the conductors being connected to an energising unit, or the fence is divided into a number of sectors with the sectors being connected to the energising unit and each sector being defined by a conductor.

According to a first aspect of the invention, there is provided a method of controlling a plurality of current-carrying conductors, the method including monitoring a predetermined parameter in respect of each conductor; and disconnecting one of the conductors from an energising unit, to which the conductors are connected in use, when the parameter of said one conductor differs from a predetermined threshold by more than a preset amount.

Hence, the method may include monitoring the variation in an electrical parameter of each conductor and, should the electrical parameter vary from the threshold by more than the preset amount, disconnecting the conductor from the energising unit.

In a first embodiment of the invention, the method may include monitoring the current in each conductor. In a second embodiment of the invention the method may include terminating each conductor with an end-of-line resistor and monitoring the voltage across the resistor. In respect of the second embodiment the method may include connecting each conductor to the energising unit via a low voltage isolating device.

Further, the method may include activating an alarm device when any one of the conductors is disconnected from the energising unit.

According to a second aspect of the invention, there is provided equipment for controlling a plurality of current-carrying conductors, the equipment including a monitoring means for monitoring a predetermined parameter in respect of each conductor; and a control means connectable intermediate- the conductors and an energising unit, the control means _being responsive to the monitoring means to disconnect a conductor from the energising unit when said parameter of that conductor differs from a predetermined threshold by more than a preset amount.

The monitoring means may comprise a threshold detector which monitors an electrical parameter of each conductor.

In a first embodiment of the invention, the threshold detector may comprise a current sensor for monitoring the current in each conductor. In a second embodiment of the invention, each conductor may terminate in an end-of-line resistor and the threshold detector may then comprise an end-of-line resistance detector for monitoring the voltage across the resistor.

Then, in respect of the second embodiment of the invention the equipment may include a low voltage isolating device via which each conductor is connectable to the energising unit.

The control means may comprise a plurality of switch means, each conductor being connectable to the energising unit by means of one of the switch means. Conveniently, the switch means may be in the form of a so_lenoid switch which is operable to open to disconnect that conductor from the energising unit.

Instead, each switch means may be an electro¬ mechanical switch having a movable contact carrier which is displaceable by a displacement device. Then, each switch may also comprise an earth terminal so that, upon disconnection of the conductor from a live terminal of the energising unit, the conductor is connected to an earth wire.

The equipment may further include a connecting means via which the monitoring means is connectable to an alarm device of the energising unit, so that the alarm device is activated when the parameter of any one of the conductors differs from the threshold by the preset amount.

The connecting means may be a switch means, either a solenoid switch or the electro-mechanical switch as described above.

As a development of the invention, the control means may include a control unit which controls disconnection of the conductors from the energising unit regardless of the state of the monitored parameter of that conductor. The control unit may comprise a microprocessor which disconnects the conductors from the energising unit in a largely random manner so ^• that potential intruders will not be aware which conductors are currently "live" .

The invention is now described by way of example with reference to the accompanying diagrammatic drawings.

In the drawings

Figure 1 shows a schematic block diagram of equipment, in accordance with a first embodiment of the invention, for controlling a plurality of current- carrying conductors;

Figure 2 shows a schematic block diagram of equipment, in accordance with a second embodiment of the invention, for controlling a plurality of current- carrying conductors; and

Figure 3 shows a schematic block diagram of equipment, in accordance with a variation of the second embodiment of the invention, for controlling a plurality of current-carrying conductors.

Referring firstly to Figure 1 of the drawings, equipment, in accordance with a first embodiment of the invention, for controlling a plurality of current- carrying conductors is illustrated, in use, and is designated generally by the reference numeral 10. The equipment 10 is intended particularly for use in controlling curren -carrying wires 12 of an electrified fence 14. The equipment 10 is connected intermediate the wires 12 and an energising unit or energiser 16 of the electrified fence 14.

The energiser 16 is a conventional energiser and the equipment 10 is configured to be connected to an output terminal 18 and an earth terminal 20 of the energiser 16. Further, the equipment 10 is connected to an alarm device input 22 of the energiser 16. It will be appreciated that, in a conventional fashion, a return wire 24 of the fence 14 iε connected to the earth terminal 20 of the energiser 16.

The equipment 10 comprises a control means 26 which is connected intermediate the terminals 18, 20 and 22 of the energiser 16 and the wires 12 of the fence 14.

The control means 26 comprises a plurality of switches 28 via which the wires 12.1 to- 12.4 are connected to the output terminal 18 of the energiser 16. Each switch 28 is in the form of a solenoid switch connecting the wires 12 in a controlled manner to the energiser 16.

The control means 26 further includes a threshold detector in the form of a current sensor 30 associated with each wire 12 of the fence 14. The current sensors 30 are connected to an alarm control switch 32 which, in turn, is connected to the alarm device input 22 of the energiser 16. The switch 32 is also in the form of a solenoid switch.

The equipment 10 is connected to the terminals 18, 20 and 22 of the energiser 16. The wires 12.1 to 12.4 of the fence 14 are, in turn, connected to their respective solenoid switches 28. The current in each wire 12.1 to 12.4 is monitored by its associated current sensor 30. If the current in any wire exceeds or is below a predetermined threshold, for example, when the wire is shorted or cut, as the case may be, the variation in the current in the relevant wire is sensed by its associated current sensor 30. The current sensor 30 then activates the solenoid switch, as shown in respect of wire 12.3, causing the switch 28 to open and disconnecting the wire 12.3 from the energiser 16. At the same time as the switch 28 is opened, the solenoid switch 32 is activated to cause a signal to be sent to the alarm device via the input 22 causing the alarm to be activated.

Referring now to Figure 2 of the drawings, equipment, in accordance with a second embodiment of the invention is illustrated and is designated generally by the reference numeral 10. With reference to Figure 1 of the drawings, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment of the invention, each wire 12.1 to 12.4 is terminated in an end-of-line resistor 34. Then, the control means 26 comprises an end-of-line resistor monitor 36. The monitor 36 comprises a reference resistor and control circuitry for controlling disconnection of the relevant wire 12.1 to 12.4 from the energiser 16.

Further, in this embodiment of the invention, the switch 28 is an electro-mechanical switch which comprises a live terminal 38 and an earth terminal 40. The earth terminals 40 of the switches 28 are connected to the earth wire 24 of the fence 14. Further, each switch 28 comprises a rotatable moving contact carrier 42 carrying a contact 44 thereon. A displacement device in the form of a drive motor and gearbox combination 48 controls rotation of the movable contact carrier 42 to displace the contact 44 from electrical contact with the contact 38 into contact with the contact 40 to isolate the relevant wire 12.1 to 12.4 from the energiser 16 and to tie that wire 12.1 to 12.4 to earth, and vice versa. The motor and gearbox combination 48 is controlled by the control circuitry of the monitor 36.

The live terminal 38 of each switch 28 iε connected to the live terminal 18 of the energiser 16 via a low voltage isolating device 50 such as a 50 Volt gas arrestor so that resistances of, for example, the transformer of the energiser 16 do not cause spurious operation of the monitors 36. It will be appreciated that the high voltage pulses output from the live terminal 18 of the energiser 16 do not "see" the isolating device 50 and pass therethrough.

The switch 32 is configured in a similar fashion to the switches 28. However, the terminal 40 of the switch 32 is left floating and is not connected to the earth wire 24. In addition, the "monitor" 36 of switch 32 does not include the reference resistor but only the control circuitry component for controlling operation of the drive motor 48 to activate the alarm of the energiser 16.

In this embodiment of the invention, the control means 26 includes a microprocessor 52 which controls opening and closing of the switches 28 in an apparently random manner, irrespective of the condition of the wires 12.1 to 12.4. Hence, potential intruders will not know which of the wires 12.1 to 12.4 is live at any one time. It will be appreciated that the microprocessor 52 can also be included with the embodiment of the invention illustrated in Figure 1 of the drawings. Referring now to Figure 3 of the drawings, a variation of the embodiment of the invention shown in Figure 2 of the drawings iε illuεtrated. Once again, with reference to Figureε 1 and 2 of the drawings, like reference numerals refer to like partε, unleεs otherwise specified.

In the embodiments of the invention illustrated in Figures 1 and 2 of the drawings, the fence 14 is defined by the wires 12.1 to 12.4 being arranged in vertically εpaced, horizontally extending parallel relationship.

In the embodiment of the invention illuεtrated in Figure 3, the fence 14 is divided into a plurality of sectors or zones with each zone being defined by one of the wires 12.1 to -12.4. Hence, as illustrated schematically in Figure 3, each wire is zig-zagged to define the zone with earth wires 24.1 to 24.4 extending between adjacent loops of the wires 12.1 to 12.4 of each sector. Thus, in thiε embodiment of the invention, when one of the switches 28 is activated, a zone of the fence 14 iε iεolated from the energiser 16 and the alarm of the energiser 16 is activated. Thus, an operator will be able to determine which sector or zone of the fence 14 is being tampered with or has been breached. A problem with electric fences is that intruders deliberately short certain of the wires of the fence to earth to create spurious alarm signalε. Eventually, in fruεtration, the energiεer 16 iε turned off by an operator rendering the fence 14 harmless enabling intruders to breach the fence to gain access to the premises. With the configuration of the equipment 10, in accordance with the invention, only one of the wires (wire 12.3 in the example illustrated in Figure 1) is disconnected from the energiser 16 at any one time with the remaining wires being retained in an energised configuration even after the relevant wire has been shorted to earth.

Claims

C L I M S

1. A method of controlling a plurality of current-carrying conductors, the method including monitoring a predetermined parameter in respect of each conductor; and disconnecting one of the conductors from an energising unit, to which the conductors are connected in use, when the parameter of said one conductor differs from a predetermined threshold by more than a preset amount.

2. The method as claimed in Claim 1 which includes monitoring the variation in an electrical parameter of each conductor and, should the electrical parameter vary from the threshold by more than the preset amount, disconnecting the conductor from the energising unit.

3. The method as claimed in Claim 2 which includes monitoring the current in each conductor.

4. The method as claimed in Claim 2 which includes terminating each conductor with an end-of-line resistor and monitoring the voltage acrosε the resistor.

5. The method as claimed in Claim 4 which includes connecting each conductor to the energising unit via a low voltage isolating device.

6. The method as claimed in any one of the preceding claims which includes activating an alarm device when any one of the conductors is disconnected from the energising unit.

7. Equipment for controlling a plurality of current-carrying conductors, the equipment including a monitoring means for monitoring a predetermined parameter in respect of each conductor; and a control means connectable intermediate the conductors and an energising unit, the control means being responsive to the monitoring means to disconnect a conductor from the energising unit when said parameter of that conductor differs from a predetermined threshold by more than a preset amount.

8. The equipment as claimed in Claim 7 in which the monitoring meanε comprises a threshold detector which monitors an electrical parameter of each conductor.

9. The equipment as claimed in Claim 8 in which the threshold detector compriseε a current sensor for monitoring the current in each conductor.

10. The equipment as claimed in Claim 8 in which each conductor terminates in an end-of-line resistor and the threshold detector compriseε an end-of-line resistance detector for monitoring the voltage across the reεiεtor.

11. The equipment as claimed in Claim 10 which includes a low voltage isolating device via which each conductor is connectable to the energising unit.

12. The equipment as claimed in any one of Claimε 7 to 11 inclusive in which the control means comprises a plurality of switch means, each conductor being connectable to the energising unit by means of one of the switch means.

13. The equipment as claimed in Claim 12 in which each switch means comprises an earth terminal so that, upon disconnection of the conductor from a live terminal of the energising unit, the conductor is connected to an earth wire.

14. The equipment as claimed in any one- of Claims 7 to 13 inclusive which includes a connecting means via which the monitoring means iε connectable to an alarm device of the energiεing unit, εo that the alarm device iε activated when the parameter of any one of the conductors differs from the threshold by the preset amount.

15. The equipment as claimed in Claim 14 in which the connecting means is a εwitch meanε.

16. The equipment aε claimed in any one of Claims 7 to .15 inclusive, in which the control meanε includes a control unit which controls disconnection of the conductors from the energising unit regardless of the state of the monitored parameter of that conductor.

17. The equipment as claimed in Claim 16 in which the control unit comprises a microprocesεor which diεconnects the conductors from the energising unit in a largely random manner.