US2767331A - Fence charger controller circuit - Google Patents

Description

' 1956 I 1. L. HURST, JR., ETAL 2,767,331

FENCE CHARGER CONTROLLER CIRCUIT Filed Nov. 25, 1952 .ITZ FEfiTLIZ-LE Leonard L. HumszJr' United States Patent FENCE CHARGER CONTROLLER CIRCUIT Leonard L. Hurst, Jr., and Ernest K. Hudson, Caldwell, Idaho, assignors to International Electric Fence (30., Inc., Caldwell, Idaho, a corporation of Washington Application November 25, 1952, Serial No. 322,420

11 Claims. (Cl. 307132) This invention relates to electric fences and, more particularly, to a fence charger for supplying controlled electric impulses to a fence wire or the like.

Electric fences have been widely accepted as effective enclosures for cattle and stock of many varieties. They pose the hazard of shocking humans and the more susceptible animals injuriously, or even fatally. Accordingly, codes setting forth safe practices under varying conditions have been promulgated and compliance with these is a requisite to a fence charger. Thus, the maximum voltage and current on the enclosure wire, the charge period, and the repetition rate must be restricted and controlled by the fence charger. Furthermore, a possible failure of the impulse forming section of the fence charger must not resutt in application of a prolonged charge to the enclosure wire, lest an animal in contact with the wire be paralyzed.

In addition to the safety problem there exist the problems of achieving long-lived .and e'fficient operation. To this end simple, long-wearing mechanical parts are desirably employed, together with such standard electrical elements as have a rugged, long-wearing characteristic. For most efficient and convenient operation, the electric fence should be energized from an alternating current source without rectification of the current. Provision of indicators to show continuing operation of the charger and to Warn of excessive loads or short circuits on the wire is also desirable to insure early restoration of the device to an eiiicien't operating condition.

Accordingly, it is an object of this invention to provide an improved electric fence system capable of efficient, safe operation over long periods of time.

Another object is to provide an improved, safeguarded electric fence system which employs but a few stable, long-lived elements.

It is a further object to doubly safeguard against the dangers of prolonged current charging by the provision of both a thermal and an electromagnetic switch to disconnect power from the fence wire before a dangerous prolongation of the charge may occur.

Another object of this invention is to provide a control for limiting the duration of the electric pulses with which the electric fence is charged and, further, to arrange a time-control element of such control for visually indicating the intermittent operation of the fence charger.

Yet a further object of this invention is the provision of a glow lamp visual indicator to give a warning upon the occurrence of an excessive load upon the output circuit.

Other and further objects and advantages of this invention will be readily perceived and may best be understood by reference to the following description, taken in conjunction with the accompanying drawing, in which:

The single figure shown is a schematic representation of the circuit and elements of an electric fence system embodying the present invention.

Using numerals to designate the illustrated and described parts, we have provided an electric fence system ice comprising a fence charger 10 having power input terminals 11 and charge output terminals 12, a charge conducting fence wire 13 connected to one of the output terminals and a grounding return conductor 14 connected to the other output terminal. The input terminals 11 may suitably be connected to a source of electrical power, preferably a steady alternating current source, to energize the fence charger 10 so that it may supply alternating electrical impulses for the fence wire 13. It will be understood that, in lieu of the fence wire, other electric shock conductors employed to control or shock living organisms might be substituted, as such are within the true scope and spirit of the present invention. The charged conductor will generally be insulated from the ground, with which the grounding conductor 14 provides a return path for current. Thus, the output circuit is generally open and transmits current only when the charged wire is grounded, as through contact with livestock or the like.

To interrupt current received at the input terminals 11 and to convert it into a train of electrical impulses, the fence charger 10 comprises a cyclic thermal current interrupting device 15 serving as a chopper or flasher device in the line of current transmission to the load. This device includes a pair of temperature responsive bimetallic switch arms 16 and 17 connected together and conductive of electricity. The less responsive arm 16 supports one of a pair of normally closed switch contacts 18, While the more responsive or thermally sensitive arm 17 supports one of a pair of normally open switch contacts 19. These contacts 18 and 19 are composed of long-wearing alloys of a type that will minimize pitting and sticking, since the normally closed contacts 18 operate as breaker points and the normally open contacts 19 have 'an important safety function.

An electrical resistance heater 20 is connected to the arm 16 for the reception of current through the normally closed contacts 18. This heater 20 is arranged to transmit su'fiicient heat to the bimetallic arm 16 to cause opening of the contacts 18 after a predetermined period of closure. The heater and the arm 16 are further designed to cool at a suflicient rate that the contacts 18 will close again after a predetermined quiescent or off period of the charger.

During a cyclic repetition of heating and cooling of the arm 16, su'fiicientheat will be received and retained by the bimetallic arm 17 to cause the normally open contacts 19 to remain closed. Should the heater 20 burn out or otherwise cease to function, the contacts 19 will open to deenergize the remainder of the fence charger. For the sake of safety, then, the contacts 19 open when the closed contacts 18 are no longer opened by automatic thermal actuation. During normal cyclic operation, however, electric impulses are transmitted at a predetermined rate of repetition by the interrupter device 15. Conveniently, a manual switch 21 is interposed in the line 22-23 between the input terminals 11 and the device 15.

While the interrupter device may be designed to determine not only the repetition rate but also the duration of each electric impulse, a more accurate and de sirable control of the impulse duration is achieved through operation of a time delay relay 25. This relay includes normally closed contacts 26 connected in the line 22 serially with the thermal switch contacts 18 and 19 to pass the electric impulses from the current interrupter section to the load. These relay contacts 25 are arranged to be opened, after passing an electric impulse, of specified duration, by the energizaticn of relay solenoid 27 through suitable time delay means. We prefer utilization of a positive temperature coeificient resistance and particularly a tungsten filament incandescent lamp 30 to control the supply of energizing current to the relay solenoid 27.

For this purpose, the lamp 3% is connected across the line 2223 in series with a variable resistance 31, effectively.

to provide a voltage divider circuit, and the relay solenoid 27 is connected across the lamp 30. Accordingly, by a suitable design, the relay 25 will not operate until the resistance of the lamp 3% has increased sufiiciently to impress upon the solenoid 27 its operating voltage. The desired time delay in relay operation may be secured then by an appropriate choice of relay and voltage divider circuit elements. The time delay in opening of the relay 25 will necessarily be less than the closed period of the breaker contacts 13, but may be made adjustable within such limits by employment of the variable resistance 31. For economy, resistance 31 may have a fixed value.

Besides the function of controlling the duration of electric impulses applied to the fence wire, this voltage divider circuit and relay provide an added safeguard against application of an uninterrupted charge to the fence. Thus, if the breaker contacts 18 and the safety contacts 19 should fail to open, the relay 25 will be energized after the preselected time delay to open its contacts 26, thereby to disconnect the fence wire 13 from the power source. In this manner both a thermal and an electromagnetic safety device are provided, such that failure of either does not impair the safeguarding function of the other and failure of both is exceedingly unlikely.

The impulse limiting section of the charger, as yet another of its functions, provides a visual indication of the production of electric impulses by the repeated glowing of the incandescent lamp 30 as each impulse is transmitted. Failure of the lamp to glow would indicate either a power failure or non-closing of the safety contacts 19. If, on the other hand, the lamp 30 glows continuously, it would be apparent that contacts 18 and 19 had stuck in their closed position. By this simple visual indication, then, an accurate and rapid check of the charger operation may be made.

To increase the voltage or potential of the electric impulses formed by the current interrupter section and the impulse limiting section, the low voltage primary coil 34 of transformer 35 is connected across the line 22-23, and the high voltage secondary coil 36 is connected through line 37-68 to the output terminals 12. In this output circuit, a current limiting resistance 40 may be selectively connected by manual switch 41 to reduce the potency of shocks imposed upon animals contacting the fence.

To provide a further indication of the condition of our electric fence system, a neon glow lamp 45 is serially connected in the output circuit and is bridged or shunted by a resistance 46 so as to glow when the output circuit is completed. If stock should ground the charged fence wire 13, for example, the intermittent charging current flowing through the resistance 46 would produce a voltage drop which, by suitable design, would intermittently ignite the glow lamp 45. An important function of the glow lamp, however, is to indicate the improper grounding of the fence wire by failure of insulators, contact with fallen tree limbs, and the like, so that the fault may be recognized and the electric fence system restored to effective operation. The glow lamp .5 and the incandescent lamp 30 have the further cooperative function of providing a check against failure of either. Thus, when the charger is on and the output circuit is intentionally closed, intermittent glowing of only one lamp would show the other lamp to be burned out.

The charger 10 is further provided with ballast condensers i) and 51 grounded to the casing (not shown) and wire 14 to minimize arcing at the breaker contacts 18, and for similar reasons ballast condenser 52 is connected across the contacts 26.

To operate our electric fence system, a suitable shock conductive fence wire 13 and a grounding conductor 14 are connected to the respective output terminals 12, and the manual switch 21 is closed to connect the charger with an alternating current source. The resist nce 29 then heats the bimetallic arms 15 and i7 nrst to close the safety contacts 19. An impulse of alternating current passes through contacts 1.8, 19 and 25 to the transformer 35 and induces a high voltage charge on the fence wire 13. Before the heated bimetallic arm 16 can open the contacts 18, the resistance of the lamp 30 is sufficiently raised by heating to cause the relay 25 to open, thereby to terminate the current impulse and thence the voltage charge on the fence wire. When, thereafter, the contacts 13 open, the resistance 29 is cooled to reclose the contacts 35 for conduction of another impulse.

It will be apparent that the current interrupter 15 determines the repetition rate, while the relay 25 and the voltage divider delay circuit 331 accurately determine impulse duration. At the same time, the interrupter 35 and the relay 25 provide a double safeguard against application of a prolonged charge to the fence. Moreover, the lamps 30 and 45 cooperate to provide a simple visual indication of the functioning of the system. In attaining these advantageous features, only a relatively few elements of rugged, long-wearing character are required, and several of these elements have multiple functions for the sake of economy.

Although we have described our invention in connection with a preferred embodiment thereof, many variations and modifications may be resorted to by those skilled in the art without departing from the principles and spirit of our invention. All of these variations and modifications must be considered within the true scope and spirit of the present invention as described and shown above and as defined by the appended claims.

We claim as our invention:

1. In an electric fence system, a fence charger comprising electric impulse forming means cyclically operative to supply a train of electric impulses, an open high voltage circuit charged by such impulses, relay means in terposed between said impulse forming means and said open circuit for terminating such impulses, and time delay circuit means cyclically energized by said impulses for operating said relay means during each impulse but after a predetermined time delay, thereby to determine the duration of each impulse charging said open circuit 2. In an electric fence, a fence charger comprising electric impulse forming means cyclically operative to supply a train of electric impulses, an open high voltage circuit charged by such impulses, a relay having normally closed contacts for passing such impulses to said open circuit, and a voltage divider circuit including a positive temperature coeflicient resistance energized cyclically by said electric impulses to energize said relay during the impulses but after a time delay determined by said resistance, thereby to open said relay contacts repeatedly to limit the duration of each impulse.

3. In an electric fence, an output transformer, an energizing circuit for said transformer including a cyclic current interrupter and a normally closed relay serially con necting said interrupter and said transformer, and a time delay circuit energized cyclically through said current interrupter to open said relay so as to limit the period of energization of said transformer through said interrupter.

4. In an electric fence system, a fence charger comprising a thermal current interrupting device, an output transformer, and relay switch means connecting said interrupting device and said transformer, and including time delay means periodically energized by said interrupting device to cause said relay means to disconnect said transformer from said interrupting device after current has been passed for a predetermined period.

5. In an electric fence, a fence charger comprising current interrupting means arranged for connection to an alternating current source, an output transformer, a solenoid relay having switch contacts in series connection with said interrupting means and said transformer, and a voltage divider circuit periodically energized by alternating current from said interrupting means, said circuit ineluding a positive temperature coeflicient resistance bridged across said solenoid relay to funrish an actuating voltage thereto after a predetermined time delay.

6. In an electric fence, a fence charger comprising an output transformer, a line for connecting said transformer to a current source, a thermal current interrupter in said line, a solenoid relay having normally closed contacts in said line between said interrupter and said transformer, and a voltage divided connected across said line for energization through said interrupter and including positive thermal coefficient resistance across which said solenoid relay is connected for time delayed actuation.

7. In an electric fence system, a fence charger comprising an output transformer, a cyclic current interrupter to supply a train of electric impulses to said transformer, relay means connected between said interrupter and said transformer for terminating each impulse, said relay means including a positive temperature coefficient resistive lamp to delay actuation of said relay means while visually indicating each actuation, and an output circuit connected to said transformer to be charged thereby, said circuit including a glow lamp and a resistance connected in parallel in said circuit to indicate passage of current therethrough.

8. In an electric fence system, an output transformer, a line for connecting said transformer to an alternating current source, impulse initiating means for cyclically connecting the current source to said line to send an electrical impulse through said output transformer, contacts in said line to open said line to interrupt each impulse from said initiating means, solenoid means operative to open said contacts, and stationary electrical timing means energized by each impulse sent by said initiating means to the output transformer to begin a timing cycle, said timing means controlling said solenoid means to automatically actuate said solenoid means and open said contacts at the end of a predetermined period and thereby limit the duration of each impulse to said predetermined period.

9. In an electric fence system, an output transformer, a line for connecting said transformer to a current source, impulse initiating means for cyclically connecting the current source to said line to send an electrical impulse through said output transformer, means in said line separate from said initiating means for interrupting each impulse from said initiating means, means for actuating said interrupting means, and a positive temperature coeflicient resistance connected in circuit with said actuating means and energized by each impulse from said initiating means to automatically operate said actuating means at the end of a predetermined period to actuate said interrupting means and thereby limit the duration of each impulse from said current source to said output transformer to said predetermined period.

10. ln an electric fence system, an output transformer, 21 line for connecting said transformer to a current source, impulse initiating means for cyclically connecting the current source to said line and output transformer to send an electrical impulse through said output transformer, electric contacts in said line for interrupting each impulse from said initiating means, solenoid means for actuating said contacts, and a positive temperature coefficient resistance means connected across said line and controlling said solenoid. means, said resistance means being operative to actuate said solenoid means to open said contacts at the end of a predetermined period of energization of the resistance means by an impulse transmitted to the output transformer over said line, thereby limiting the duration of each impulse to said predetermined period.

11, In an electric fence system, an intermittent alternating current impulse type energizing circuit for delivering energy to a charge conducting fence wire, an impulse limiting relay having contacts in said energizing circuit, said relay having a solenoid for actuating said contacts, and an impulse operated time delay circuit including a positive temperature coefficient resistance connected to said energizing circuit and operative upon energization of said energizing circuit to actuate said solenoid after a predetermined heating period, said solenoid being operative upon actuation thereof to open said contacts in said energizing circuit and thereby to interrupt delivery of energy to the charge conducting fence wire.

References Cited in the file of this patent UNITED STATES PATENTS 2,226,514 Pignolet Dec. 24, 1940 2,294,343 Nunn Aug. 2, 1942 2,294,344 Nunn Aug. 2, 1942 2,316,211 Agnew et al. Apr. 13, 1942 2,398,442 Moore Apr, 16, 1946

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