Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1982-04-20
1985-06-11
Levy, Stewart J.
Communications: electrical
Condition responsive indicating system
Specific condition
324 51, 256 10, 340650, 340652, 340540, H05C 300, G08B 2300, G01R 1900
Patent
active
045231877
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvements in electric fencing monitoring systems, particularly for multiple fence arrangements of relatively long lengths.
2. Description of Prior and Related Art
Electric fences utilizing an energizer at one end for producing a pulse along the length of the fence have been known for many years and are presently being used more frequently due to a more general awareness of their advantages over conventional fences. The pulse generated is of such a level and frequency that it will deter passage of animals and the like through the fence. The advantages of electric fences are particularly significant in farm fencing arrangements where temporary paddocks are desired and electric fences are becoming more extensively used for this purpose.
Electric fences permit a simpler, lighter and therefore cheaper construction than conventional fences as there is no longer any need to make design allowances for animals endeavouring to push through the fence to get to pastures on the other side.
However, problems do arise if a power loss of a certain dimension, or a complete power loss occurs along the fence; because of the light construction of the fence stock losses through the fence can occur or damage to crops can result from intrusion of ones own stock or foreign animals into crop growing areas. Therefore there is a need for some means of simply determining when a fault occurs along a conductor of a sufficiently significant nature to make the conductor ineffective for its design purpose and when such fault occurs an alarm is raised.
Some proposals have been made for alarm systems for these types of fences, however, these have generally been complex or ineffective in operation, particularly for fences of considerable length. An electric fence system suitable for lengthy systems has been proposed by us as described in our published Australian patent application No. 509,325. This system operates with a monitoring device including an alarm and a reflector means in the fence which reflects pulse signals to the monitoring device which will activate the alarm if the pulses are absent or are weak. This system has been used in the field and found to work satisfactorily. The present invention aims to remove the need for providing a reflector device in an electric fence alarm system and yet operates effectively.
SUMMARY OF THE INVENTION
There is provided according to the present invention a monitoring system for an electric fence having an energizer means for applying an electric pulse to a fence conductor, said system comprising means for sensing the voltage of said pulse in said conductor, means for sensing the current in the conductor, the value of current and voltage being related to the magnitude of said pulse and ambient conditions at the conductor, monitoring means for computing signals related to said current and voltage and adapted to operate alarm means when the computed signal falls outside a predetermined range of values or to indicate a reading on indicator means.
Conveniently said monitoring means includes means for detecting a rapid fall in current level (as may be caused by a breakage) whereby said alarm or indicator means is activated. Said monitoring means includes means for measuring or detecting a rise or fall in current level (as may be caused by an unacceptable drop in potential in the fence through insulator breakdown or moisture leads to earth) whereby said alarm is activated in the case of rise beyond predetermined limits. Additionally or alternatively an indicator is provided to give a reading of current levels at any given moment in operation.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be described in greater detail having reference to the accompanying circuit diagrams in which
FIG. 1 is a schematic block diagram of an electric fence circuit.
FIG. 2 shows details of voltage current measurement, curvature and mixing circuits.
FIG. 3 shows an alternative mixing circuit.
FIG. 4 shows a detailed switchin
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"Voltage Detection Circuit"; IBM Technical Disclosure Bulletin, vol. 3, No. 6, p. 37; 11-1960; F. L. O'Malley.
Levy Stewart J.
Noland Tom
Norman W. Hutchinson & Sons PTY. Ltd.
Teltscher Erwin S.
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