Electric fence network

Details Electric fence network Electric fence network

1998-12-16

2001-01-16

Browne, Lynne H. (Department: 3629)

Fences

Electric

C174S16100R, 26

Reexamination Certificate

active

06173942

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention involves an electric fence network, consisting of branches, preferably running horizontally and vertically, connected to each other in the form of a network. The branches are made of a non-conducting material and are provided with an electrical conductor. Alternatively, the branches may be constructed directly as an electrical conductor. The conductor can be connected to a voltage-conducting terminal (post) of an electric fence device.
Network-like electric fences of this type, are constructed with various grid widths, preferably to confine sheep, chickens, rabbits, pigs, and other small animals.
In the prior art all horizontal branches, possibly with the exception of the lowest branch, are provided with an electrical conductor, in particular as a twisted cable, or are directly constructed as such, so that the individual conductors, connected in parallel, can be connected to the voltage-conducting post of an electric fence device. In order to have an especially effective grounding, it is also known therein to twist the lowest branch with an electrical conductor that functions as a ground conductor.
A problem with this construction according to the prior art is that with severe fouling by growth encrustation or with a deep snow cover, the voltage in the electric fence drops sharply. Thus, it is not infrequent that on account of the growth encrustation or the electrical conduction across the snow cover, a voltage impulse of, for example, 9000V will only have available a voltage impulse of 3500V on the spot for a confinement effect.
From European patent publication EP O 610 490, an electric fence is already known consisting of a network of non-conducting branches, which are connected to each other in a relatively complex manner. This network is passed through in a wave-like manner by at least two electrical conductors of high electrical conductivity, which are phase-shifted by 180°. This known network has a complex construction, which makes its manufacture expensive, and furthermore, the distribution of the voltage-conducting conductor is not optimal.
SUMMARY OF THE INVENTION
Based on this background, an object of the present invention is thus to construct the electric fence described at the outset in such a way that loss or leakage of electric energy into the ground is prevented as much as possible.
The achievement of this object occurs according to the present invention, wherein only a predetermined number (e.g., a minority) of the horizontal branches are constructed as conductor branches having relatively high conductivity and the other horizontal branches (e.g., a majority) are constructed as non-conductor branches, wherein on the horizontal conductor branches, vertical conductor branches are respectively connected at predetermined intervals as stub cables.
Through the horizontal conductor branches having relatively high conductivity and connecting to the voltage-conducting post of the electric fence device, like a ring circuit or busbar, practically no noticeable voltage drop occurs over the length of the fence, i.e. the electric potential is essentially equal at the points at which the respective stub cables connect. Since the length of the vertical conductor branches connected as stub cables is relatively short, because of the relatively low fence height compared to the fence length, the effect of a possible lower conductivity becomes practically unnoticeable and the voltage drop is only slight.
An especially cost-effective construction, because of its simplicity, can be obtained according to a further embodiment of the invention, if only the horizontal branch that is furthest from ground is constructed as a conductor branch having a high conductivity and the stub cable conductor branches extend essentially across the fence height at a sufficient distance from the ground to maintain insulation.
It is alternatively also conceivable that according to another embodiment of the invention, only a middle horizontal branch is constructed as a conductor branch having high conductivity and the stub cable conductor branches extend both towards the ground as well as away from the ground.
Both embodiments require only one single expensive high conductivity, which extends preferably as a ring circuit or busbar over the entire fence length. Both embodiments are thus very cost-effective.
Fundamentally, depending on the application, more than one horizontal conductor branch having relatively high conductivity can also be provided. Thus, it is conceivable according to another embodiment of the invention, that two spaced, horizontal branches are each constructed as conductor branches having high conductivity, and the stub cable conductor branches, connected to both horizontal conductor branches, extend essentially across the height of the fence, while maintaining the insulation by a sufficient spacing from the ground.
An embodiment of this type makes it possible, in particular, to use stub cable conductor branches that have a relatively high specific resistance.
In order to provide an effective electrical grounding, the electric fence according to a further embodiment of the invention is constructed in such a way that, in addition, the horizontal branch near the ground is constructed as a conductor branch having high conductivity, that is connectable to the ground as a ring circuit.
Especially effective in the area is thus the electrical grounding, if according to a further embodiment of the invention, vertical conductor branches, which lie interspersed between the vertical conductor stub cable branches and likewise have a low conductivity, are connected as stub cables at predetermined intervals to the groundable horizontal conductor branch.
Particularly advantageous is an embodiment in which the vertical conductor branches have a substantially lower electrical conductivity than the S horizontal conductor branches. The background for this is that conductors with a higher electrical conductivity on the order of magnitude of 0.1 ohm/meter, which are preferably used in the form of stranded conductors, are comparatively more expensive than conductors with lower electrical conductivities, by up to a factor of 10. Owing to the present cost pressure caused by international competition, this is a considerable cost factor.
A lower electrical conductivity of the vertical conductor branches is noticeable, however, with advantages not only in terms of cost. It also causes a smaller loss or leakage of energy into the ground in case of fouling by growth encrustation or by contact with a snow cover.
It is preferable, because it is especially cost-effective and nevertheless completely effective, if according to an embodiment of the invention, the specific resistance of the horizontal conductor branches lies in the range of 0.1-0.5 ohm/m and the specific resistance of the vertical stub cable conductor branches lies in the range of 1-50 ohm/m.
It is, however, expressly emphasized that the object of the present invention is achieved even with a network-like electric fence in which the difference between the electrical conductivity of the horizontal conductor(s) and the electrical conductivity of the vertical stub cables is zero or very small.


REFERENCES:
patent: 317908 (1885-05-01), Willianson
patent: 319300 (1885-06-01), Morton
patent: 401095 (1889-04-01), Wood
patent: 768077 (1904-08-01), Reynolds et al.
patent: 2172050 (1939-09-01), Mayberry
patent: 2530247 (1950-11-01), Koonz
patent: 4196890 (1980-04-01), Einhorn
patent: 4493480 (1985-01-01), Nichol
patent: 6036175 (2000-03-01), Harper
patent: 231466 (1991-05-01), None
patent: 241302 (1995-09-01), None
patent: WO 95/01720 (1995-01-01), None

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