This application generally relates to electrical power distribution units, such as wall-mountable and portable extension socket outlet units (power strips/bars).
Power distribution units provide an arrangement of electrical sockets allowing multiple electrical devices to be powered from a single electrical socket. These power distribution units are usually provided in the form of wall mount units and portable extension power strips. As exemplified in
Typically, power distribution units 10 are enclosed inside electrically insulating housing (not shown) to prevent accidental user contact with the electrified bus bar and socket elements of the units.
Design of power distribution units usually mainly concerns selection of suitable materials and sufficient cross-section areas of the electrical conductors to enable the power distribution unit to supply desired electrical power without being damaged (e.g., due to over heating). However, the design considerations usually do not concern the magnetic fields emanating from the power distribution units during their operational use, which may be a source of interference in operation of electrical appliances (e.g., wired/wireless data communication, audio cables, medical devices, and suchlike), and may also present health hazards to persons residing near these units during their use.
There have been some attempts to attenuate magnetic fields and/or electromagnetic interferences (EMI) produced by electricity carrying elements. For example, U.S. Pat. No. 5,986,355 suggests reduction of magnetic alternating fields in a vehicle which comprises at least one electrical system having at least two elements of which at least one comprises one or more components generating and/or consuming electricity, and which are connected through at least one connecting cable in which flows a current having an alternating current component generating a low frequency magnetic field. This publication further describes use of at least one detecting element arranged to detect the alternating current component, and means for generating a compensating current with the use thereof. The compensating current flows adjacent to the connecting cable in such a way that the low frequency magnetic field is reduced or eliminated.
In another example, described in U.S. Pat. No. 7,310,242, a distribution box used for enclosing an electrical connection in an electrical wiring system is arranged to include a housing that is resistive to penetration by electromagnetic fields and a plurality of electrical conductors that form the electrical connection. A mirror plate is disposed within the housing and generates mirror currents to suppress electromagnetic fields generated by current flowing through the plurality of electrical conductors.
There is a need in the art for electric power distribution units capable of suppressing magnetic fields emanating from bus bar systems of power distribution units. Power distribution units are designed to deliver significant amounts of electric power over bus bar elements of their bus bar systems to outlet sockets from which electrical loads (appliances) are supplied. The arrangement and connectivity of the bus bar elements inside a power distribution unit typically cause constructive interference of the magnetic fields emanating from the bus bar elements, such that when the unit is electrically loaded during use, magnetic fields emanating from the bus bar elements may be significantly intensified. Such undesired high magnetic fields may induce interferences in various electric devices (e.g., pacemakers, wireless devices, communication devices and wires), and cumulative exposure thereto presents health hazards (e.g., leukemia).
The inventors of the present invention have found that it is possible to significantly suppress/attenuate magnetic fields emanating from a bus bar system of a power distribution unit, by uniformly dividing the electric currents delivered through the bus bar system through a plurality of sub-bus-bar elements arranged in parallel to each other and uniformly distributed in a compact intervening fashion in a defined volume (or plane), such that each sub-bus-bar element is located adjacent at least one other sub-bus-bar element associated with electric current of a different phase or current direction.
The term intervening fashion/arrangement is used herein to refer to arrangements of electric carrying elements (e.g., bus bar or sub-bus-bar elements) wherein each element is located adjacent at least one other element associated with electric current of a different phase or current direction. For example, and without being limiting, in some embodiments at least some electric carrying elements are located between two other elements associated with electric current of a different phase or current direction, or surrounded by some number of the elements associated with electric current of a different phase or current direction.
By proper selection of the cross-sectional areas of the sub-bus-bar elements, the electric current delivered by the bus bar system is evenly distributed over the defined volume (or plane) through the sub-bus-bar elements. Each of said sub-bus-bar elements carries a predefined portion of the electric current of the specific electric phase or current direction with which the sub-bus-bar element is associated. Accordingly, each sub-bus-bar element carries a significantly smaller amount of electric current (50%, or less) relative to the total electric current of the specific electric phase or current direction with which the sub-bus-bar element is associated, such that the sub-bus-bar elements can be placed in closer proximity to each other in the defined volume.
As each sub-bus-bar element is carrying a relatively smaller amount of electric current, the intensity of the magnetic filed emanated therefrom, when electrically loaded, is also relatively smaller, such that the intervening arrangement of the sub-bus-bar elements in close proximity to each other, such that each sub-bus-bar element is located adjacent at least one other sub-bus-bar element associated with electric current of another phase or another direction causing destructive interference of the magnetic fields emanating from the sub-bus-bar elements, substantially attenuates the intensity of the overall (i.e., obtained by summation of all magnetic moments) magnetic field emanated from the bus bar system of the power distribution unit.
To this end, the present invention in some of its embodiments provides arrangements and designs to substantially suppress magnetic fields emanating from power distribution units. This is achieved by implementing each electricity carrying bus bar (e.g., phase and neutral bus bars, and/or electrical positive and negative bus bars) by at least two sub-bus-bar elements electrically connected to each other, and arranging the bus bar system such that each sub-bus-bar and bus bar element is located adjacent at least one other sub-bus-bar or bus bar element associated with electric current associated with a different phase or current direction (e.g., opposite direction). As will be exemplified hereinbelow, the sub-bus-bar and bus bar elements may be arranged in parallel to each other aligned in an intervening fashion in a defined plane, or uniformly distributed in an intervening fashion in a defined volume.
For example and without being limiting, in some embodiments a conventional bus bar system of a standard power distribution unit is modified by adding at least two sub-bus-bars to the original bus bar system e.g., aligned in parallel in the same plane (or in a parallel plane) of the bus bars of the original system. One of the added sub-bus-bar elements is electrically connected to the bus bar element carrying the electrical phase of the system, while the other sub-bus-bar element is electrically connected to the bus bar element carrying the electrical neutral of the system, and the sub-bus-bar elements are positioned in parallel to the original bus bar elements of the bus bar system such that each bus bar and sub-bus-bar element of the bus bar system is located adjacent at least one other sub-bus-bar or bus bar element associated with an electrical current of a different phase or current direction.
In another non-limiting example the bus bar system is arranged such that each bus bar and/or sub-bus-bar element carrying an electrical phase is located adjacent at least one element carrying an electrical neutral, and each bus bar and/or sub-bus-bar element carrying an electrical neutral is located adjacent at least one element carrying an electrical phase. In this way, the magnetic fields emanating from the bus bar elements and from the sub-bus-bar elements destructively interfere with each other such that the magnitude of overall magnetic field emanated from the power distribution unit during its operation is substantially suppressed/attenuated and minimized.
The modified bus bar system may be designed to guarantee maximal attenuation of magnetic fields emanating from its various elements by ensuring that the following condition is met for all magnetic moments Mi and dipoles Pi:
where N is a positive integer indicating the total number of magnetic emanating elements (e.g., bus bar or sub-bus-bar elements), and i is an integer index indicating a particular dipole/moment of a specific bus bar or sub-bus-bar element. Accordingly, the location, cross-sectional area, geometrical arrangement and/or connectivity of each electricity carrying element of the power distribution unit may be modified in order to meet the conditions set in equation (1).
In one broad aspect the present invention provides a power distribution unit, comprising a bus bar system connectable to an electric power feed line and comprising for each specific electric phase or current direction of the feed line at least two bus bar elements electrically connected to each other, said bus bar elements are arranged one parallel to the other and may be aligned such that each element is situated adjacent at least one other element carrying electric current associated with a different phase or current direction, and socket outlets each electrically connected to said bus bar elements.
According to one aspect there is provided a power distribution unit comprising a bus bar system connectable to an electric power feed line and comprising at least two bus bar elements electrically connected to each other and associated with an electric phase of the feed line and at least two bus bar elements electrically connected to each other and associated with an electric neutral of the feed line, the bus bar elements arranged one parallel to the other such that each element is situated adjacent at least one element carrying electric current of a different phase or current direction. The power distribution unit further comprises socket outlets electrically connected to at least one bus bar element associated with the electric phase and to at least one bus bar element electrically connected to the electric ground.
In some applications the power distribution unit comprises a bus bar element associated with an electric ground of the feed line, where the socket outlets are further electrically connected to the ground bus bar element.
In some embodiment the bus bar elements are arranged substantially in the same geometric plane. For example, and without being limiting, the bus bar elements associated with the electric phase and with the electric neutral may be arranged in an intervening fashion in the same geometric plane, wherein the ground bus bar element is situated at a center of the bus bar arrangement (e.g., in parallel to the other bus bar elements). Alternatively, the ground bus bar element may be situated anywhere adjacent (e.g., on top, or at bottom) to the other bus bar elements.
In some possible embodiments the bus bar elements are arranged in two substantially parallel geometric planes. For example, and without being limiting, the power distribution unit may comprise two bus bar elements associated with the electric phase and two bus bar elements associated with the electric neutral. In such an application the bus bar elements may be arranged such that one bus bar element associated with the electric phase and one bus bar element associated with the electric neutral are arranged in parallel in a first geometric plane (e.g., with the ground bus bar situated between them), and one other bus bar element associated with the electric phase and one other bus bar element associated with the electric neutral are arranged in parallel in a second geometric plane, said geometric planes being substantially parallel one to the other.
As another non-limiting example, the bus bar elements may be arranged such that the two bus bar elements associated with the electric phase are arranged in parallel in a first geometric plane, and the two bus bar elements associated with the electric neutral are arranged in parallel in a second geometric plane being substantially parallel to the first geometric plane, such that at least one bus bar element is situated above a midpoint between two bus bar elements situated in the other geometric plane and carrying electric currents associated with a different phase or current direction.
In possible implementations, the power distribution unit comprises a ground bus bar situated between bus bar elements arranged in one of the geometric planes. Alternatively, the ground bus bar may be situated adjacent (e.g., in parallel) bus bar elements arranged in one of the geometric planes.
According to another aspect there is provided a method for suppressing/attenuating magnetic fields emanating from a bus bar system, the method comprising using two or more sub-bus-bar elements to implement each bus bar element of the bus bar system, cross sectional areas of the two or more sub-bus-bar elements associated with a specific bus bar element are set so as to guarantee uniform distribution of electrical current associated with said specific bus bar element between said two or more sub-bus-bar elements, arranging the sub-bus-bar elements in parallel to each other and in an intervening fashion such that each sub-bus-bar element is located adjacent at least one other sub-bus-bar element associated with an electric current of a different phase or direction, and electrically connecting sub-bus-bar elements associated with a specific phase or direction of electric current between themselves.
In some embodiments the sub-bus-bar elements are aligned in the same geometric plane. Alternatively, the sub-bus-bar elements may be uniformly distributed in an intervening fashion in a defined volume.
According to yet another aspect there is provided a method for modifying a power distribution unit, comprising placing at least one sub-bus-bar element in parallel to each bus bar element of the power distribution unit associated with a specific phase or direction of electric current, and electrically connecting between the at least one sub-bus-bar element and the bus bar element associated with the same specific phase or direction of electric current. The method may comprise connecting one or more sockets to the sub-bus-bar elements.
In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings. Features shown in the drawings are meant to be illustrative of only some embodiments of the invention, unless otherwise implicitly indicated. In the drawings, like reference numerals are used to indicate corresponding parts, and in which:
The various embodiments of the present invention are described below with reference to
The present invention provides designs and arrangements for substantially suppressing intensity of magnetic fields emanating from electrical power distribution units. With reference to
In some embodiments a bus bar system is constructed using at least two sub-bus-bar elements electrically connected to each other to implement the bus bar carrying the electric phase of the system, and at least two sub-bus-bar elements electrically connected to each other to implement the bus bar carrying the electric neutral of the system. The sub-bus-bar elements are arranged in parallel to each other such that each sub-bus-bar element is situated adjacent at least one other sub-bus-bar element associated with a different electric phase or current direction.
In the power distribution unit 20 exemplified in
As seen, in this arrangement each element of the modified bus bar system 14′ is positioned in parallel to, and adjacent, at least one other element associated with electrical current of a different phase or current direction. For example, the bus bar element 14p carrying the electric phase is positioned adjacent and parallel to sub-bus-bar element 12n electrically connected to the electrical neutral, the sub-bus-bar element 12n electrically connected to the electric neutral is positioned in parallel and adjacent to bar elements 14p and 12p electrically connected to the electrical phase of the system, and the bus bar element 14n carrying the electric neutral is positioned adjacent and parallel to sub-bus-bar element 12p electrically connected to the electrical phase. The modified bus bar system 14′ is electrically connected to the electric power feed line 11 by the wires 11p, 11g and 11n, connecting the electric phase, ground and neutral of the feed line 11 to the respective bus bar elements 14p, 14g and 14n.
In the example shown in
It is noted that all of the socket outlets 15 and 15a are electrically connected in this example to the bus bar element 14g carrying the electrical ground of the system. In some possible embodiments the bus bar element 14g associated with the electrical ground of the system may be also implemented by two or more sub-bus-elements electrically connected to each other and arranged in parallel to the other bus bar and sub-bus-bar elements. However, the electrical elements associated with the electrical ground of the system usually do not carry substantial electrical currents during normal operation of the power distribution units, such that splitting the ground bus bar element into two or more sub-bus-bar elements usually does not substantially improve suppression of the intensity of the magnetic field.
More particularly, the sub-bus-bar element 12n electrically connected to the electric neutral of the system is positioned adjacent the bus bar element 14p carrying the electric phase of the system and adjacent sub-bus-bar element 12p electrically connected to the electric phase of the system, and the sub-bus-bar element 12p electrically connected to the electric phase of the system is positioned adjacent the bus bar element 14n carrying the electric neutral of the system and adjacent sub-bus-bar element 12n electrically connected to the electric neutral of the system. In this way the magnetic fields emanating from the bar elements associated with the electric phase and with the electric neutral of the system 24 destructively interfere with each other, such that the overall intensity of the magnetic field emanating from the bus bar system 24 is substantially suppressed.
For example and without being limiting, the sub-bus-bar element 12n may be placed above a midpoint between the bus bar element 14p carrying the electric phase and the bus bar element 14g carrying the electric ground, and the sub-bus-bar element 12p may be placed above a midpoint between the bus bar element 14n carrying the electric neutral and the bus bar element 14g carrying the electric ground. Thus, in some embodiments the bar elements may be arranged to form a trapezoid sectional shape, where the smaller base of the trapezoid is formed by the newly added sub-bus-bar elements 12n and 12p respectively carrying the electric neutral and phase of the bus system 24, and the large base of the trapezoid is formed by the bus bar elements 14p and 14n respectively carrying the electric phase and neutral of the bus system 24, and wherein the bus bar element 14g carrying the ground is positioned at the center of the large base of the trapezoid.
In the different arrangements exemplified in
In
It is noted that the splitting of the bus bar elements of the power distribution unit exemplified in
More particularly, in
An electrically conducting wire 2n is used to electrically connect between the sub-bus-bar elements 13n associated with the electric neutral of the system and situated in the upper geometric plane P2, and another electrically conducting wire 2p is used to electrically connect between the sub-bus-bar elements 13p associated with the electric phase of the system and situated in the bottom geometric plane P1.
While the bus bar element 13g associated with the electric ground is situated in
The distance g between each pair of sub-bus-bar elements associated with the same electric current direction (or phase) and situated in the same geometric plane is substantially the same. The distance h between the geometric planes in which the elements associated with the electric phase and neutral of the system is made as small as possible, and may generally be set to comply with customary standards.
The above examples and description have of course been provided only for the purpose of illustration, and are not intended to limit the invention in any way. As will be appreciated by the skilled person, the invention can be carried out in a great variety of ways, employing more than one technique from those described above, all without exceeding the scope of the invention.
Number | Date | Country | Kind |
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227278 | Jul 2013 | IL | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IL2014/050609 | 7/7/2014 | WO | 00 |