US2743376A

US2743376A - armistead

Info

Publication number: US2743376A
Authority: US
Publication date: 1956-04-24
Anticipated expiration: 1973-04-24

Description

April 24, 1956 F. v. ARMISTEAD ELECTRIC ENERGY LIMITING APPARATUS 2 Sheets-Sheet 1 Filed Oct. 10, 1952 April 24, 1956 F. v. ARMISTEAD ELECTRIC ENERGY LIMITING APPARATUS 2 Sheets-Sheet 2 Filed 001..10, 1952 0 1n: 124 5 ys United States Patent 2,743,376 ELECTRIC ENERGY LIMITING APPARATUS Frederick V. Armistead, St. Louis, Mo. Application October 10, 1952, Serial No. 314,147 6 Claims. (Cl. 307-35) This invention relates to electric energy limiting apparatus and in particular to an apparatus which may be used in lieu of the usual meter with installations, the power consumption of which is constant while the installation is in use, but the use of which is intermittent. An illuminated outdoor sign is an example of such an installation.

Heretofore each outdoor illuminated sign has been provided with a service entrance switch, fuses, meter loops, and a time switch (which elements are usually installed separately and individually in the field by the sign owner); and a kilowatt hour meter, installed and read from time to time (generally monthly) by the power supplier. The use of kilowatt hour meters involves not only investment of capital in the meters themselves,

installation, maintenance and testing costs, but also the continued cost of periodic meter readings, and the cost of calculating, rendering and collecting frequent individual bills. The reading of the meters and subsequent processing of accounts frequently costs the power supplier more than half the price charged for the energy consumed. This is particularly true of signs like the ordinary illuminated billboards which consume a relatively small amount of energy. The universal power suppliers practice of billing for each individual sign involves a corresponding amount of labor and cost on the part of the sign owner.

While the advantage of a fiat yearly rate for such signs has been recognized, the power suppliers have generally not been willing to charge on such a basis. The possibility that light bulbs or other load of a greater wattage or in greater number than that contracted for might be used, and the inability to predetermine, with assurance and accuracy, the amount of use have seemed insuperable obstacles to the allowance of such a yearly rate basis.

One of objects of this invention is to provide a ing drawing.

In accordance with this invention generally stated the energy consumption of a sign or the like is forecast, and consumption in excess of the forecast is precluded, by the provision of a time switch and a circuit breaker having an accurately calibrated overload element, all coordinated to limit the power drawn and the time period of its supply, to the requirements contracted for; and all confined so that their control elements are inaccessible replacement by any one except an authorized representative of the power supplier and their connections are protected to prevent the possibility of their being jumpcd." A time switch having an astro- 2,743,376 Patented Apr. 24, 1956 contracted for but which trips open when the current drawn slightly exceeds the rated value for a certain period of time. If the operating handle of the circuit breaker is accessible to other than authorized representatives of the power supplier, the device should be trip-free.

The time switch is electrically operate and is preferably provided with an auxiliary spring-operated carry over device to keep the switch in adjustment when its power supply is interrupted.

The time switch operating circuit may be protected by the circuit breaker,

trically operated time switch.

Those parts of the elements of the apparatus which control the total energy consumption of the installation, i. e. the maximum current and/or the length of time during which the load circuit is energized during a given period, are arranged to be placed under seal. Likewise, the connections of the load circuit to and through those elements are under seal. On the other hand, fuses in the load circuit and time switch operating circuit, if such fuses are provided, and the operating handle of a resettable circuit breaker are preferably made accessible without breaking the seal. Provision may also be made for testing of the circuit but no permanent adjustment of the maximum energy consumption is possible without breaking the seal. The device of the invention eliminates the necessity of using a kilowatt hour meter, because the maximum energy consumption of an installation supplied with the device can be predetermined for any given period. The entire device forms a compact unit which may be factory assembled. It is enclosed in a relatively small weather-proof container. The weather-proof container may itself be locked and/ or sealed so as to prevent unauthorized access to any working part of the device.

In the drawings:

Figure l is a diagrammatic view showing a device of this invention in use with an illuminated bill-board;

Figure 2 is a front elevation of a device constructed in accordance with one embodiment of this invention;

Figure 3 is a sectional view taken along the line 3-3 of Figure 2;

Figure 4 is a front elevation in accordance with another embodiment of this invention, part of the cover being broken away to reveal the relationship of the parts; and,

Figure 5 is a sectional view taken along the line 5-5 of Figure 4.

Referring now to the drawing, Figure 1 shows an energy limiting apparatus 1 of this invention connected beand a group of electric lamps 3, which in this illustration, constitute the load. The several parts of the energy limiting apparatus are weather-proof and tamper-proof box 4. The essential features of construction of the box 4 are the same in' any of the embodiments shown, and the same reference numerals are used ments of the box itself in all of in Figures 2-5 the box 4 is of welded construction, and is provided with a removable lid 5. One end of the lid 5 fits snugly beneath an overhanging ledge 6 across what is the upper front edge of the box 4 when the box is mounted vertically. The other end of the lid 5 is provided with a lid tab 7. A box tab 8, a companion of the lid tab 7, projects outwardly from the lower end of the box 4. The lid tab 7 and box tab 8 are provided to indicate the elethe figures. As shown tab 15. up from the seal tab 15, hole 17 to take a threaded seal ,the car 16 is provided with a 20, totake a seal wire 21.

with matching openings to take a simple fastener, like a bolt, or padlock, or a seal. Depending flanges 12, around three sides of the lid 5, fitting tightly around the box 4, serve to make the box weather-proof. Projecting inwardly from the lower end of the box is a seal In the embodiment shown, an ear 16 is struck and the seal tab 15 has a tapered screw 18. The seal screw 18 is equipped with a transverse passage 19, while correspondingly large hole A cover tab 25 having a tapped hole' 26 to take a bolt 27 extends inwardly from the upper end of the box 4. Knockouts 28 are provided in the side walls of the box 4.

In the embodiment of the device shown in Figures 2 and 3, the cutout-limiting elements of the device consist of a circuit breaker 30, of the type which automatically opens in response to excess current, and a time switch 40. The circuit breaker 30 acts as a line switch. It is resettable and is preferably of the trip-free type. Either a thermal or electromagnetic (or combination thermal-electromagnetic) type circuit breaker may be used. A suitable circuit breaker for use with this embodiment is an electromagnetic type with a time delay mechanism in the form of a dash pot or the like, such as the Magnette, manufactured by Heinemann Co. Such a circuit breaker trips almost instantaneously in response I to a severe overload, as with a short circuit, but with a moderate overload, a definite time interval elapses, varying inversely with the amount of overload, before the circuit is broken. It has an operating handle 31.

The circuit breaker 30 is releasably mounted in the box 4 on a bracket 32. The bracket 32 is equipped with a pair of spring clips 33, taking into recesses 34 in one end wall of the body of the circuit breaker 30, and with a pair of fixed fingers 35 takinginto recesses 36 in the other end wall of the body of the circuit breaker 30.

The time switch 40 includes an electric motor and operates like an electric clock. It is provided also with a reserve spring motor which serves to continue the operation of the switch without interruption in case of power outage. The time switch is designed to close and open at predetermined intervals which may be over a long period of time, such as years, if the switch is equipped with an astronomic dial 41. It can be seen that the knid of astronomic dial needed for the time switch 40 varies with the latitude of the installation; and its setting, with the location of the installation within a given time Zone. When properly adjusted, such a time switch will operate to energize the load circuit at the same time with respect tosunset every day of the year. Time switches-adaptable to this use are well-known in the art and are produced by the Sangamo Electric Company, Springfield, Illinois, among others. The time switch 40 is mounted in the box 4, alongside the circuit breaker 30, on a time switch bracket 42, by means of screws 43.

The device of this invention may be used with either 2-wire or 3-wire power systems; In the embodiment shown in Figure 4, a 2-wire system is shown in full lines, and will first be described. However, the setup for a 3-wire system is indicated in dotted lines.

As shown in solid lines in this embodiment, two wires from the power main 2, enter the box 4 through a knockout 28. One of the wires is a ground wire 50, which is connected to an independent terminal 51. The other,-

hot, wire 52 is connected to a terminal 37 of the circuit breaker'30. A wire 53, connected to the remaining terminal 38 of the circuit breaker leads to a terminal 54 of the time switch 40. The time switch 40 is provided with

additional terminals

55, 56 and 57. Terminal 55, to which the time switch electric motor is connected, is connected to terminal 54. Terminal 6, the ground terminal for the time switch electric motor, is connected by a wire 59 to independent terminal 51. Terminal 57 to which terminal 54 is connected through the time switch,

Cit

is connected to the hot side of a 2-Wire load circuit. The ground side of the load circuit is connected to independent terminal 51. In the 3-Wire system, a second circuit breaker section 30' is added, to a terminal 37' of which a second hot wire 52, from the power main 2, is connected. A wire 53', connected to the remaining terminal 38' of the circuit breaker section 30' leads to a terminal 54 of the time switch 40. A terminal 57 to which terminal 54 is connected through the time switch is thus available to be connected to a third wire of a 3-wire load circuit.

A cover plate 60, proportioned to'fit closely within the box 4, is placed over the two energy-limiting elements and all of the wiring in the box 4. The cover plate 60 is supported by the cover plate supporting tab 25 at one end, and the seal tab 15 at the other. At the appropriate location above the hole 26 inthe cover plate tab 25, the cover plate 60 is provided with a bolt-receiving hole 61, and above the seal-screw receiving hole 17 of the seal tab 15 the cover plate 60 is provided with a seal screw-receiving hole 62. It is provided with an opening 63 proportioned to allow the ear 16 to project therethrough. The cover plate 60 also is provided with an opening 64 above the operating handle 31, through which that handle projects to allow its manipulation. A transparent window 66 may be provided in the cover plate 60 over the face of the astronomic dial 4-1. When the cover plate 60 is placed under seal, no change in the current limiting setting of the circuit breaker 30 or the time interval of the time switch 40 may be made without breaking the seal.

It may also be found desirable to provide openings in the cover plate 60 above part of the time switch 40 as shown at 65 in dotted lines in Figure 2, through which the load circuit may be tested. In lieu of such openings, such an arrangement as that requiring the use of a key which can be retracted only when the load circuit is broken, may be used. In either event, the testing arrangement is such as to make changing the setting of the time switch 40, or the load setting of the circuit breaker 30 impossible without breaking the seal on the cover plate 60.

In assembling the device of this embodiment, a time switch 40. constructed for the appropriate latitude, and a circuit breaker 30 constructed to permit the expected load to be carried but to trip it that load is exceeded for a given period (depending upon the amount of overload) are mounted within the box 4 and-wired. The box 4 is mounted at a convenient location with respect to a sign board or the like. The wires if the power main 2 are connected to the proper terminals of the circuit breaker 30, and the wires of the load circuit are connected to the proper terminals of the time switch 40. The time switch electric motor is started, the time switch astronomic dial 4, is set, the cover plate 60 is slipped into place and bolt 27 and seal screw 18 are screwed down. The cover plate is then sealed in place, generally by the power supplier, by inserting a seal wire though the transverse passage 19 of the seal screw 18 and the hole 20 in the car 16, and sealing the wire against removal. The lid 5 is then put on the box 4, and bolted, locked, or sealed in place. The lid is ordinarily sealed only when the installation is to be left idle for an extended period. Then, arrangement can be made for obtaining a minimum rate thereon, and the power supplier may be permitted to put its seal on the lid to ensure that the installation is not put into operation without its knowledge.

The time switch 40 is set to operate at any predetermined interval. For example, in the case of billboard installations the time switch is often set to energize the load circuit approximately at sunset and to deenergize the load circuit at midnight. The circuit breaker 30 is rated to permit a given load to be carried but to trip open In the billboard illustration, such an excessive load in a sm ll installation might be an amount equal to the substitution in the load circuit of one lamp of the next higher standard wattage. For example, with a circuit breaker rated at 300 watts in an installation carrying three IOU-watt bulbs, if a ISO-watt bulb be substituted for one of the 100-watt bulbs, the circuit breaker will trip open after a short time. In a large installation the tolerated overload in terms of watts must be greater to allow for fluctuation in the line voltage,

but percentage wise, the overload tolerated may be less than that of a small installation. Since the length of time which elapses between the initiation of overload and the tripping of the circuit breaker is almost certain to be less than the length of time the entire load is cut oft, the power supplier will not lose by the substitution of lamps (or other devices) of high wattage.

It can be seen that since the circuit breaker 30 acts as a line switch and since the time switch 40 is connected to the load side of the circuit breaker 30, the tripping of the circuit breaker 30 stops the electric motor of the time switch. When this happens, the spring motor of the time switch takes over to prevent the time switchs getting out of adjustment. In the case of an illuminated sign installation, the length of the carryover of which the spring motor must be made capable will be determined by the likelihood of the sign owners attention being brought to the fact that his sign is not operating. In general this will be a relatively short time, because the sign does not operate during the day so that there is no chance of the circuit breakers being tripped at that time, and the failure of a sign to operate at night is immediately apparent.

In the embodiment shown in Figures 4 and 5 a time switch 140 of the same character as the time switch 40 of the embodiment shown in Figures 2 and 3 may be used. While a circuit breaker of the same type as was used in the embodiment first described may also be used, a'circuit breaker 130 of the thermostatic type such as the Westinghouse Electric Companys Motor Sentinel, which has provision for interchangeable heater elements to vary the rating of the circuit breaker, will be described as used in this embodiment. In addition to the circuit breaker 130 and the time switch 140 the device of this embodiment is provided with a fused switch 105, in which are two fuses. One of the fuses 106 is relatively heavy; the other fuse 107 is of relatively light capacity. In this embodiment, in which a 2-wire system is illustrated, the ground wire 50 from the power main 2 is connected to an independent terminal 151. The hot wire 52 is connected to one end of each of the

fuses

106 and 107. A wire 171 connects the heavy fuse 107 with a terminal 134 of the circuit breaker 130. A wire 173 connects the light fuse with a time switch motor terminal 155. The remaining terminal 138 of the circuit breaker 130 is connected by a wire 153 to a terminal 154 of the time switch 140. Terminal 154 of the time switch 140 is connected through the time switch to a terminal 157 to which the hot side of a 2-wire load circuit is connected. The ground side of the time switch electric motor circuit is connected through a terminal 156 to the independent terminal 151. The ground side of the load circuit is also connected to independent terminal 151.

In the arrangement of this embodiment, the time switch electric motor is separately fused from and connected independently of the circuit breaker 130. Therefore, while the time switch electric motor is protected against an extreme overload from the power main, it will continue to run so long as there is no power outage in the power main, whether the circuit breaker 130 is closed or open. The relatively heavy fuse 106 must be rated higher than the circuit breaker, and is simply a safety measure.

A cover plate 160 similar to the cover plate 60 of the embodiment first described is provided with an opening 164 above an operating handle 131 of the circuit breaker 130, and in addition with an opening 166 above the fuses 6

t

106 and 107, to permit the replacing of the fuses. In all other respects, the cover plate is identical with the cover plate 60 of the embodiment first described.

Except that the time switch electric motor continues to run independently of the condition of the circuit breaker 136), the operation of this embodiment is substantially the same as the operation of the embodiment first described. The heater elements of the Motor Sentinel" circuit breaker are interchangeable and closely calibrated in amperes. Therefore, unlike the magnetic type circuit breakers which must be replaced completely (although this is easily accomplished in such a mounting as is illustrated in Figures 2 and 3) the rating of the Motor Sentinel circuit breakers may be changed by simply replacing one heater element with another. However, in either embodiment no change in rating can be accomplished without removing the cover plate.-

In both embodiments, all of the wiring within the box 4 is protected against tampering, by the cover plate, which is sealed by the power supplier. Thus the energylimiting elements cannot be shunted out within the box 4 by unauthorized persons.-

The time delay of thermostatic and dash pot-equipped electromagnetic circuit breakers may be utilized to integrate the power consumption of blinker type apparatus. For example, if a blinker is placed in the load circuit between the load and the device of this invention, the blinker operating in such a way that the load is on only two-thirds of the time, a circuit breaker rated at twothirds of the full load can be used, provided that the time lag of the circuit breaker is slightly greater than the interval during which the load is on. Thus if the charge by the power supplier is based upon the product of the rating of the circuit breaker and the total length of time during which a load circuit is energized by the workings of the time switch, that rate will reflect the actual amount of current used, whether the load is steady or regularly intermittent.

An undamped electromagnetic circuit breaker may be used in those installations in which it is desired to break the load circuit immediately upon its being overloaded in excess of the rated load.

Numerous variations in construction of the device of this invention within the scope of the appended claims will be apparent to those skilled in the art in the light of the foregoing disclosure. The box 4 may be made of any suitable material, such as steel or aluminum, and may be constructed in various different ways to render it weather-proof. The cover plate, too, may be made of plastic, glass, metal or the like. It may be secured by more than one seal. Various fusing arrangements, such, for example, as eliminating the heavy fuse 106 in the second embodiment described, may be used.

Since the time for which a sign or other apparatus will be in operation can be exactly determined from the setting of the time switch, and since the power consumption for a given time cannot exceed the Wattage for which the circuit breaker is rated, the maximum amount of electricity consumed in any given period can easily be predetermined by calculation.

Ordinarily the energy limiting apparatus will be placed nder seal by the power supplier, after the time switch and circuit breaking device have been properly set.

It can be seen that this invention provides a compact, weather-proof, tamper-proof unit, which may be factory assembled and may easily and quickly be installed; which requires no regular maintenance or adjustment; which eliminates the need for a kilowatt hour meter; and which requires no meter reading, with its attendant clerical work, thus reducing overhead and loss of time both for the owner of an installation equipped with a device of this invention and for the power supplier.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In an electrical power system supplying an outdoor comprising an enclosure in part under seal of the power distributor, an astronomical time switch contained Within the sealed portion of said enclosure and connected periodically to open and close the circuit to said sign,

and a circuit breaker connected to open the circuit to the sign, said circuit breaker having a power-responsive element rated at said predetermined average power consumption of the sign and contained Within the sealed portion of said enclosure.

2. Apparatus as set forth in claim 1, wherein said 'circuit breaker further includes a reset element extending from the sealed portion of said enclosure.

3. In the method of operating an outdoor illuminated sign of predetermined normal power consumption by means of an astronomical time switch, the improvement comprising the steps of providing a circuit breaker rated to said predetermined normal power consumption of the sign, connecting the sign through said time switch and circuit breaker directly to the service conductors of a power distribution system, and placing said time switch and circuit breaker at least in part under the seal of said power distributor.

4. The method set forth in claim 3, wherein said circuit breaker is provided with a power-responsive elemen: and a reset element, and wherein the powerresponsive element is placed under seal while the reset element is left accessible.

5. A control for an outdoor illuminated sign, the power consumption of which is to 'be held to a predetermined value, comprising a box divided into at leasttwo compartments, a first openable panel closing one of said compartments, means for sealing said first panel in its closed position, a second openable panel closing asecond compartment of the box, an astronomical time switch disposed within said first compartment so as to be accessible only upon opening of said first panel, and a circuit breaker having a current-responsive element and a reset element, said cuirent-responsive element being mounted within said first compartment so as to be accessible only upon opening of said first panel, and said reset element being disposed at least in part within said second compartment so as to be accessible upon opening of said second panel.

6. A control as set forth in claim 5, wherein said first panel is mounted behind said second panel.

References Cited in the file of this patent UNITED STATES PATENTS