WO2003026362A1

WO2003026362A1 - Electric fence and energizer therefor

Info

Publication number: WO2003026362A1
Application number: PCT/AU2002/001310
Authority: WO
Inventors: Kenneth S Mcbryde
Original assignee: Kenneth S Mcbryde
Priority date: 2001-09-21
Filing date: 2002-09-20
Publication date: 2003-03-27
Also published as: AUPR784301A0

Abstract

An electric fence (90) is disclosed which includes an energizer (100) having a first energizer terminal (1) and a second energizer terminal (2), and at least two electric fence wires including a first live wire (101) connected to the first energizer terminal (1) and a second live wire (102) connected to the second energizer terminal (2). Wherein the energizer (100) provides an alternating pulsed output whereby alternate pulses are directed, through the first energizer terminal (1) and second energizer terminal (2) respectively, to the first and second live wires (101, 102) which constitute alternately active and non-active fence wires.

Description

ELECTRIC FENCE AND ENERGIZER THEREFOR

Technical Field

The present invention relates to electric fences. In particular the present invention relates to energizers for electric fences, and to electric fences and terminating devices.

Background of Invention

Electric fences have been employed for a substantial period of time to keep animals within an enclosed area. They have also found application in certain security systems. Electric fences are preferred to barbed wire fences, as they provide the necessary deterrent factor without the risk of injury associated with barbed wire.

An electric fence operates through the use of an energiser which periodically generates high voltage electrical pulses which are sent through the fence wires. The pulses are of a very high voltage usually around 6,000 volts but operate for a very short amount of time, usually in the realm of 10 to 500 microseconds. An animal receives an electric shock upon touching the wire which deters it from attempting to break through the fence. However because of the extremely short duration of the pulse the animal is not harmed. Both the maximum voltage and pulse length are specified by industry standards. The relevant Australian standards are AS3350.2.76 and AS3014. These standards put "safe" limits on peak voltage, pulse width, pulse rate as well as joule and current limits for specified loads.

Electric fence systems are generally installed as an open circuit. Upon an animal coming into contact with the fence the circuit is completed with the current flowing through the animal and back to the energiser through an earthing system. The earthing system can be through the ground to an earth rod that is placed near the energiser to receive the returning current. Alternatively one of the wires of the fence can act as an earth return wire. The use of a dedicated earth wire has the disadvantage of additional expense in installing extra lengths of wire, which may not be necessary if a ground return system can be used. In particularly arid climates and areas of low soil conductivity, an earth return wire may be required. It is also possible to employ a combination of earthing systems where the earth wire is periodically earthed to ground such as through a metal post, such as a star post. This combination permits the electric fence to provide operative effect when a circuit is completed between an active wire and the earth wire or between an active wire and the ground. The operative effect once a circuit is completed between an active wire and the ground is maintained, notwithstanding the losses that would be expected between the earthing point and the primary earth post adjacent the power source, as the circuit will be completed through the metal post nearest the earthing point and through the earth wire connected thereto. For an electric fence system to be effective a high voltage must be maintained within the circuit comprising the energiser, fence, animal and earth return system. Because electric fences generally operate in rural areas vegetation and other debris can grow up against the lower wires of the electric fence thereby conducting current away from the fence and reducing the overall voltage. This condition is known as a leakage.

A number of systems have been employed to reduce the occurrence of leakage to provide a more effective electric fence system. These systems are constructed on the basis that electric fence energisers periodically produce a series of pulses along each of the fence wires with each of the pulses reaching the maximum voltage at the same time or, in other words the pulses frequencies are in phase. The most common arrangement to achieve this is for an energizer output to be connected to all live wires in parallel. Typically, this is for a variety of reasons including the type of animal to be contained or excluded. The use of parallel wires has an additional benefit of reducing line resistance. In such systems, any leakage occurring on any one wire, such as the bottom wire, will also degrade the performance of each of the other wires. In an alternative system a pulse of opposite polarity is generated along alternate wires. The pulse itself in each wire is typically of a magnitude approximately half that of the conventional system. Although leakage on one wire should not degrade performance of the opposite polarity wire or wires, a pulse of the full magnitude can only be experienced by an animal if it touches more than one wire at once. The effect when a circuit is completed between one active wire and the ground is typically half that of a conventional system and this may be further reduced by losses as the distance between the animal and the earthing post adjacent the energizer is increased.

We have now found that by alternately charging wires on an electric fence advantages over prior systems may be achieved.

Summary of Invention

In one aspect the present invention resides broadly in an electric fence including:- an energizer having a first energizer terminal and a second energizer terminal, and at least two electric fence wires including a first live wire connected to said first energizer terminal and a second live wire connected to said second energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed, through the first energizer terminal and second energizer terminal respectively, to the first and second live wires which constitute alternately active and non-active fence wires.

It is preferred that when an animal contacts at least two fence wires a current pulse is returned to the energiser by the non-active fence wire. Alternatively when an animal contacts an active wire, a current pulse is returned to the energiser by the ground and an earth stake at the energiser.

It is also preferred that the electric fence also includes:- a terminating device having a first terminating device terminal, and a second terminating device terminal respectively connected to the first and second live fence wires; said first terminating device terminal and said second terminating device terminal being connected to ground whereby current that has entered the ground may return via a non-active wire.

It is also preferred that the terminating device also includes a further terminating device terminal, and wherein the alternating pulses are combined and directed through the further terminating device terminal. In the present invention, alternate pulses are directed from the energizer through respective energizer terminals to the corresponding electric fence wires that are attached thereto. In a preferred embodiment, the electric fence wire that is out of phase with the alternate pulses is earthed. Thus the first energizer terminal and the second energizer terminal may be earthed out of phase with the alternate pulses. Alternatively the first and second live wires may be connected to earth out of phase with the alternate pulses.

Of course, the electric fence wires that are out of phase with the alternate pulses need only be maintained at a different electric potential in order for an electric fence to be effective. However, it is preferred for the sake of convenience and simplicity that the electric fence wires that are out of phase with the alternating pulses will be earthed at the energizer, at intermediate positions along the electric fence and at the end thereof.

The electric fence of the present invention includes at least two electric fence wires where a first live wire and a second live wire are connected to an energizer and the shocking pulse is alternately directed through the first and second live wires. In the present invention, the alternate shocking pulses may be sequentially directed through three or more electric fence wires. Alternatively, the electric fence may include a plurality of sets of electric fence wires where each set of fence wires includes at least first and second live wires, each first live wire in the sets being connected to the first energizer terminal and each second live wire in the sets being connected to the second energizer terminal. In embodiments where there are more than two live wires in each set, for example "n" live wires in each set, each nth live wire in the sets is connected to an nth energizer terminal. The electric fence of the present invention may employ a combination of live wires, selected wires of which may be connected to the combined pulses of the further terminal of the energizer, and other live wires may be connected to the first and second terminals.

Accordingly, in another definition the fence wire configuration of the present invention can be regarded a constituting a plurality of sets of wires, there being at least one wire in each set and each set being connected to a respective terminal of the energiser for receiving alternating pulsed outputs. Thus the invention may also be regarded as residing broadly in an electric fence including:- an energizer having at least a first energizer terminal and a second energizer terminal, and at least two sets of electric fence wires there being at least one live wire in each set, each set being connected to a respective energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed, through the respective energizer terminals to the set of fence wires connected thereto, the sets of fence wires constituting alternately active and non-active fence wires.

Each of the live wires of the electric fence will be insulated from the respective fence posts such that they are insulated from each other and from a direct connection to earth. Each of the live electric fence wires connected to the first or second energizer terminal may be connected to earth via a terminating device as described herein.

The energizer includes a first energizer terminal and a second energizer terminal whereby alternating pulsed outputs are directed through the respective terminals. In electric fence configurations that incorporate more than two live wires through which a shocking pulse is sequentially passed the energizer may include three or more terminals.

The energizer may preferably include a capacitor for providing the pulsed output. The capacitor may preferably discharge alternately to the first and second terminals or sequentially to three or more terminals.

In a preferred embodiment where alternating pulses are directed to first and second output terminals respectively, the capacitor may be connected essentially to the windings on one side of a transformer and the ends of the winding are respectively connected to earth through a solid state switch such as an SCR or a thyristor. The respective solid state switches being activated by a timer mechanism, the timing of which controls the rate at which the alternating pulses are directed through the respective first and second terminals.

The energizer may also incorporate an earth terminal that may be earthed by connection to one or more metal stakes driven into the ground. This earthed terminal may provide an earth to the first energizer terminal and the second energizer terminal out of phase with the alternate pulses, or, in other words, when the respective terminals are at their resting potential.

The energizer may also include a further terminal that provides a combined pulsed output that combines the alternating pulses. This further terminal may be used to energize an electric fence of a conventional type that may include a single live wire. Alternatively, the further terminal may be connected in parallel to a number of live wires on an electric fence.

Terminating devices may be provided at intermediate points along the electric fence whereby the respective first and second live wires are earthed through the terminating device. The terminating device connects the respective first and second live wires to ground, effectively out of phase with the alternating pulses that are delivered from the energizer and permits current discharged to ground from a pulse to be returned to the energizer via a non-active wire. In a preferred configuration, the first and second live wires may be connected to a half bridge. The half bridge may then be connected to earth via an earth rod. The half bridge may comprise a pair of diodes that connect the respective first and second wires to an earth rod.

In another form, the terminating device may be a half bridge whereby a pair of diodes are so configured as to connect the respective first and second wires to a single output through which the combined pulses may be directed such as to energise a single wire electric fence.

In a further form, both the previous functions may be included in one terminating device whereby in a full bridge configuration of diodes, the respective first and second wires are connected to provide an output at one terminal and provide connection to an earth rod at another terminal. The electric fence of the present invention may also incorporate various components that may be used in conventional electric fences such as lightning diverters, volt meters, fault finders, monitors, flood gate controllers and spring gates.

In another aspect this invention resides broadly in an energizer for an electric fence having at least two electric fence wires, the energiser including:- a first energizer terminal, and a second energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed through the first energizer terminal and second energizer terminal respectively.

It will be appreciated that in this aspect of the invention, the energiser may variously also include the features defined above when referring to the electric fence per se, as preferred optional features of the energiser.

Thus in the energiser alternate pulses directed through one of the energiser terminals may be returned to the energiser via the other terminal to thereby complete a circuit to the energiser. The energiser may also include an earth terminal whereby alternate pulses directed through one of the energiser terminals may be returned to the energiser via the ground and an earthing stake connected to the earth terminal to thereby complete a circuit to the energiser.

In a further aspect this invention resides broadly in a terminating device for an electric fence having at least two electric fence wires including a first live wire and a second live wire for alternating pulses to be passed respectively therethrough, said terminating device including:- a first terminating device terminal, and a second terminating device terminal; said first terminating device terminal and said second terminating device terminal being respectively connectable to the first and second live fence wires and connectable to ground whereby current that has entered the ground may return via a non-active wire.

The terminating device may also include a further terminating device terminal wherein the alternating pulses are combined and directed through the further terminating device terminal.

In a further aspect this invention also broadly resides in a method of forming an electric fence, said method including:- setting up at least two electric fence wires; connecting said at least two electric fence wires to an energizer, and providing an alternating pulsed output whereby alternate pulses are directed through a first live wire and a second live wire respectively, the first and second live wires constituting alternately active and non-active fence wires. The method may also include returning a current pulse to the energiser when an animal contacts at least two fence wires, by the non-active fence wire.

The method may also include including returning a current pulse to the energiser when an animal contacts an active fence wire, by the ground and an earth stake at the energiser.

The method may also include including returning a current pulse to the energiser when an animal contacts an active fence wire, by the ground, an earth stake connected to a terminating device connected to the at least two electric fence wires and the non-active fence wire.

Description of Drawings

In order that this invention may be understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate preferred embodiments of the invention and wherein: FIG. 1 is a view of an embodiment of an electric fence of the present invention;

FIGS 1A and 1B respectively illustrate the alternate pulses on the energiser outputs and the combined pulses on a single live wire;

FIG. 2 is a systematic diagram of the circuitry of an energizer 100 as seen in FIG 1 of the present invention, and

FIG 3 is a circuit diagram of the terminating device 130 seen in FIG 1.

Description of Preferred Embodiment of Invention

In FIG 1 there is shown an electric fence 90 having four live wires 101a, 101b, 102a, and 102b. The live wires 101a and 101b are connected to a single wire 101 that is connected to a first terminal 1 on the energizer 100. Electric fence live wires 102a and 102b are connected to a single wire 102 that is connected to the second energizer terminal 2. The wires are all insulated from the fence posts 110. An earth terminal 106 is connected to earth via an earth rod 107. The energizer also includes a combined or conventional output terminal 108. Periodically along the electric fence the respective live wires 101a and 101b may be connected to one side of a terminating device 120 and live wires 102a and 102b may be connected to the other side of the terminating device 120. The terminating device 120 may be earthed via an earth rod 107. A further terminating device 130 may be provided with one side of the terminating device being connected to a first live wire 101b and the other side of the terminating device being connected to a live wire 102a. A earth rod 107 may be connected to the terminating device and a single electric fence wire 103 may be connected to an output on the terminating device that provides the combined pulses from the live wires 102a and 101b.

FIGS 1A and 1B are graphical representations of the pulses directed down the respective live wires. The pulses passed through live wires 101 , 101a and 101b are labelled with numeral 1 in FIG 1A. The pulses shown as 2 in FIG 1A indicate the pulses directed down live wires 102, 102a and 102b. In FIG 1B the combined pulses directed down the live wire 103 are shown.

A schematic diagram of circuitry which could be used to implement the alternating pulse energiser in accordance with the present invention is shown in FIG. 2. The individual components are all well understood by those skilled in the art and accordingly their individual functions will not be described in detail.

At 300 there is a voltage doubler, the function of which is to build a high voltage on the capacitor 306 with respect to the internal circuit ground 320. The internal circuit ground 320 is not necessarily an external ground, such as earth, but may be a floating ground. The voltage doubler is connected to the internal circuit ground 320. A timer device 302 is connected to a pair of switching gates 305, a flip flop 304 and a pair of solid state switches 308 and 310. The main capacitor of the energiser 306 is connected to the voltage doubler 300 and also to the internal circuit ground 320. The main capacitor 306 is charged by the voltage doubler and has its output connected to the primary windings of a transformer 312. The solid state switches 308 and 310 are also connected to the primary windings of the transformer 312 and operate to alternate the polarity of the pulses delivered by the discharge of the main capacitor 306. The said alternation occurs on the primary winding of the transformer to avoid switching the large voltage induced on the secondary windings of the transformer. The output of the secondary windings of the transformer are connected to a series of diodes 316a - 316d which operate to permit the earth terminal to pick up current that has flowed to ground and also to combine the pulsed output for a conventional output. The pulses, having been switched by the circuitry 302, 304, 305, 308 and 310 will then deliver the pulses alternately along wire 1 (322 in FIG 2) and then wire 2 (324 in FIG 2). The operation of the timer 302 may be altered to deliver different pulse frequency depending, for example, on the number of wires in the system. Upon an animal coming into contact with wire 1 a pulse will travel through wire

1 , through the animal and back through wire 2 which acts as the earth return system during its inactive period. Alternatively upon the pulse being delivered through wire 2 324, wire 1 322 will act as the earth return system during its inactive period.

Terminating device 130 seen in FIG 1 is described in FIG 3 in more detail as terminating device 318 incorporating two half bridges. The upper half bridge combine the pulses from the alternate live wires. The lower half bridge of suitably rated diodes 330 establishes the ground reference for the two alternating pulse live wires 322 and 324.

As will be apparent to those skilled in the art, the terminating device can include lightning protection circuitry (not shown). This will protect not only the circuitry of the terminating device, but also has the added advantage of providing additional lightning protection for the energizer itself by absorbing/diverting lightning induced pulses along the fence. Lightning protection can also of course be incorporated in the energizer. It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is set forth.

Claims

1. An electric fence including:- an energizer having a first energizer terminal and a second energizer terminal, and at least two electric fence wires including a first live wire connected to said first energizer terminal and a second live wire connected to said second energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed, through the first energizer terminal and second energizer terminal respectively, to the first and second live wires which constitute alternately active and non-active fence wires.

2. An electric fence as claimed in claim 1 , wherein when an animal contacts at least two fence wires a current pulse is returned to the energiser by the non-active fence wire.

3. An electric fence as claimed in claim 1 , wherein when an animal contacts an active wire, a current pulse is returned to the energiser by the ground and an earth stake at the energiser.

4. An electric fence as claimed in claim 1 , and also including:- a terminating device having a first terminating device terminal and a second terminating device terminal respectively connected to the first and second live fence wires; said first terminating device terminal and said second terminating device terminal being connected to ground whereby current that has entered the ground may return via a non-active wire.

5. An electric fence as claimed in claim 4, wherein said terminating device also includes a further terminating device terminal, and wherein the alternating pulses are combined and directed through the further terminating device terminal.

6. An electric fence as claimed in claim 1 , wherein the electric fence wires that are out of phase with the alternating pulses are earthed at the energizer, at intermediate positions along the electric fence and at the end thereof.

7. An electric fence as claimed in claim 1 , and including:- a plurality of sets of electric fence wires each set including at least first and second live wires, each first live wire in the sets being connected to the first energizer terminal and each second live wire in the sets being connected to the second energizer terminal.

8. An electric fence as claimed in claim 1 , wherein the energizer includes a capacitor for providing the pulsed output, the capacitor discharging alternately to the first and second terminals or sequentially to three or more terminals.

9. An electric fence as claimed in claim 8, wherein the capacitor is connected to the windings on one side of a transformer and the ends of the winding are respectively connected to earth through a solid state switch.

10. An electric fence as claimed in claim 9, wherein the respective solid state switches are activated by a timer mechanism, the timing of which controls the rate at which the alternating pulses are directed through the respective first and second terminals.

11. An electric fence as claimed in claim 1 , wherein the energizer includes an earth terminal for earthing by connection to one or more metal stakes driven into the ground.

12. An electric fence as claimed in claim 11 , wherein the energizer includes a further terminal for providing a pulsed output that combines the alternating pulses.

13. An energizer for an electric fence having at least two electric fence wires, the energiser including:- a first energizer terminal, and a second energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed through the first energizer terminal and second energizer terminal respectively.

14. An energiser as claimed in claim 13, wherein alternate pulses directed through one of the energiser terminals is returnable to the energiser via the other terminal to thereby complete a circuit to the energiser.

15. An energiser as claimed in claim 14, and including an earth terminal whereby alternate pulses directed through one of the energiser terminals may be returned to the energiser via the ground and an earthing stake connected to the earth terminal to thereby complete a circuit to the energiser.

16. A terminating device for an electric fence having at least two electric fence wires including a first live wire and a second live wire for alternating pulses to be passed respectively therethrough, said terminating device including:- a first terminating device terminal, and a second terminating device terminal; said first terminating device terminal and said second terminating device terminal being respectively connectable to the first and second live fence wires and connectable to ground whereby current that has entered the ground may return via a non-active wire.

17. A terminating device as claimed in claim 16 and also including:- a further terminating device terminal: wherein the alternating pulses are combined and directed through the further terminating device terminal.

18. A method of forming an electric fence, said method including:- setting up at least two electric fence wires; connecting said at least two electric fence wires to an energizer, and providing an alternating pulsed output whereby alternate pulses are directed through a first live wire and a second live wire respectively, the first and second live wires constituting alternately active and non-active fence wires.

19. A method of forming an electric fence as claimed in claim 18, and including returning a current pulse to the energiser when an animal contacts at least two fence wires, by the non-active fence wire.

20. A method of forming an electric fence as claimed in claim 18, and including returning a current pulse to the energiser when an animal contacts an active fence wire, by the ground and an earth stake at the energiser.

21. A method of forming an electric fence as claimed in claim 18, and including returning a current pulse to the energiser when an animal contacts an active fence wire, by the ground, an earth stake connected to a terminating device connected to the at least two electric fence wires and the non-active fence wire.

22. An electric fence including:- an energizer having at least a first energizer terminal and a second energizer terminal, and at least two sets of electric fence wires there being at least one live wire in each set, each set being connected to a respective energizer terminal; wherein said energizer provides an alternating pulsed output whereby alternate pulses are directed, through the respective energizer terminals to the set of fence wires connected thereto, the sets of fence wires constituting alternately active and non-active fence wires.