Abstract:
A circuit and system having an inductive data link from one or more user-side phases to a plurality of line-side phases by individual data transformers having a winding coupled to the particular phase by a high-permeability ferrite material. The resulting connection across the primary (or primaries) and secondary (or secondaries) selectively provides and efficient coupling of data in a multi-phase environment including step-down distribution transformers and “Δ”-to -“Y” configured circuits while maintaining isolation at the power line frequency. Further embodiments include transfer to selected phases or single-phase applications, and selective signal-pass or -reject filtering.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention relates to power mains data couplers, in particular, to data couplers providing a data path across multiphase transformers. 
       BACKGROUND OF THE INVENTION  
       [0002]    Residential and commercial power distribution comprising AC power mains are typically optimized for efficiency of power distribution at the particular frequency, voltage and current of the end user in the particular power service area. As important is the need for flexibility to provide the various combinations of voltage and power for differing end users who may be juxtaposed. The typical U.S. distribution systems provide a three-phase “medium” voltage (10-30 KV) pole-to-pole line to which a first step-down to 480 V 3 phase for a drop to the large/commercial building is typically provided by pole transformers. In the building, the voltage is typically further dropped to 120/208 (3-phase) and distributed to neighboring and/or adjoining users, or alternately first distributed at 480V to neighboring users and the subsequently reduced to 120/208. 
         [0003]    Increasingly for contemporary business and residential users, a separately wired data infrastructure is unattractive, inflexible or simply unavailable, and data over the power line (power mains) becomes interesting. However, blocks to effective power mains data transfer are the facility transformers, particularly the 3-phase 480-to-120/208 transformers that are used to provide the necessary voltage step-down. Furthermore, the final (480-to-120/208) step-down also often transforms the power distribution from 3-phase “Δ” (or “Y”) format to 3-phase “Y” format, which further complicates data transfer on the power mains through the transformer. 
       SUMMARY  
       [0004]    The present invention provides an inductive data link from one or more user-side phases to a plurality of line-side phases by individual data transformers having a winding coupled to the particular phase by a high-permeability ferrite material. The resulting connection across the primary (or primaries) and secondary (or secondaries) selectively provides and efficient coupling of data in a multi-phase environment while maintaining isolation at the power line frequency. 
         [0005]    Further embodiments include transfer to selected phases or single-phase applications, and selective signal-pass or -reject filtering. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING  
         [0006]    These and further features of the present invention will be better understood by reading the following Detailed Description, together with the Drawing, wherein: 
           [0007]      FIG. 1  is a block diagram of an exemplary multi-user power distribution system having data conductivity between the users; and 
           [0008]      FIG. 2  is a schematic diagram of one embodiment according to the present invention having a “Δ” to “Y” transformer; and 
           [0009]      FIG. 3 . is a schematic diagram of one embodiment according to the present invention having a “Y”-to-“Y” transformer. 
       
    
    
     DETAILED DESCRIPTION  
       [0010]    A typical power multi-user distribution installation  50  is shown in  FIG. 1 , wherein a “medium” voltage (e.g. 10-30 KV) Δ 3-phase 3-wire power line  52  is carried by to the facility by a pole  54  which typically holds a 3-phase transformer  56  (or 3 each single phase transformers) having a secondary voltage of 480 volts distributed over a 3 wire, 3-phase Δ (or Y) drop  58  to the facility  60  which in the embodiment shown, distributes the  480 V power to individual units  62 ,  64  and  66  each having a subsequent corresponding step-down transformer  72 ,  74  and  76  receiving the distributed 3 wire, 3-phase 480 V (“low” voltage) power into their respective primary winding connections  82 ,  84  and  86 . Each unit  62 ,  64  and  66  transformer  72 ,  74  and  86  is typically a “Δ”-to-“Y” transformer provides a voltage step-down to a nominal 120 volts (low voltage) from a phase to the neutral wire, or nominally 208 volts from one phase to another. Shown separately and without the ‘Y’ neutral wire, the transformer  72 ,  74  and  76  secondary 3-phases correspond to paths  91 ,  92 ,  93 ;  94 ,  95 ,  96 ; and  97 ,  98 ,  99 , respectively. Within each unit, the electrical loads are typically distributed as equally as possible over and among each of the 3-phases (e.g. paths  91 ,  92  and  93  have connected loads as equal as possible), wherein a data equipment, e.g.  102 ,  104  and  106  is connected to one of the phases  93 ,  96  and  99  respectively. The other loads and loads connected to the other phases (e.g.  91 ,  92 ,  94 ,  95 ,  97  and  98 ) typically exist but are not shown for clarity. Alternate embodiments include a “Δ”-to-“Y” pole transformer  58  and “Y”-to-“Y” transformers  72 ,  74  and  76  power distribution, discussed further below. 
         [0011]    It is desirable to provide data communication between and among the data equipment  102 ,  104  and  106  over the power paths  93 ,  96  and  99  to each other, but a data path connection typically requires a pass through transformers  72 ,  74  and/or  76 . According to one embodiment of the present invention, data is transferred around the transformers by a data link including a first data transformer comprising a winding  112  coupled to a representative secondary winding wire  93 ,  96  and/or  99  by a magnetic core  122  providing efficient signal transfer at data frequencies, typically comprising a ferrite core having a permeability in excess of 1,000, the present embodiment having a permeability in excess of 3000. Alternate embodiments include additional transformers  112  connected to each of the secondary phases discussed further in  FIGS. 2 and 3 , below, and according to a single core simultaneously coupling (e.g. surrounding) all secondary phase paths. The data path around each transformer  72 ,  74  and  76  is completed by connection to a primary-side transformer or transformers illustrated by winding  114  coupled to one or more of the primary phase wire with a corresponding magnetic core typically comprising substantially the same material as core  122 , discussed above. In the embodiment  50  of  FIG. 1 , the windings  112  and  114  comprise relatively few turns of wire around or through the core, typically merely juxtaposing a single length of wire along the corresponding primary side wire  82 ,  84 ,  86  and surrounded by the core i.e. 122  or  124 . 
         [0012]    A more detailed view  150  of one embodiment according to the present invention showing a three-phase “Δ” input connection  152 A,  152 B and  152 C to corresponding primaries  154 A,  154 B and  154 C respectively coupled to corresponding secondary windings  158 A,  158 B and  158 C via magnetic cores  156 A,  156 B and  156 C and having a “Y” output configuration with each phase provided at connections  162 A,  162 B and  162 C with a neutral connection  162 N. In the embodiment shown, three separate, single phase transformers may be used, or the primary and secondary windings may share a common core as indicated by core elements  156 D and  156 E connecting the transformer cores  156 A,  156 B and  156 C to provide a single, 3-phase transformer. With regard to a typical multi-user installation such as  50  illustrated in  FIG. 1 , the implementation  150  is replicated within each unit,  62 ,  62 ,  66 , and so forth. 
         [0013]    A typical illustration of data from or to the user side of the transformer is shown as being presented by a data equipment  100  having a data signal connected or coupled to the power mains path  162 A inductively with a coil  126  and core  116 ; however other forms of coupling, e.g. capacitively (not shown) are within the scope of the present invention. Data is received from that power mains path  162 A with a corresponding data winding  164 A and core  166 A, and connected to three series connected windings  172 A,  172 B and  172 C, each coupled to a primary phase wire  152 A,  152 B and  152 C. While it is preferable to have signal coupled to each of the primary phase connections as a single data coupled (e.g. with data winding  172 A and core  174 A) phase wire cannot be reliably connected to a corresponding signal-coupled primary lead of another unit transformer for transfer to data equipment in the corresponding unit, the present does include data coupling to selected primary winding wires less than each of the 3-phase wires, in such case the unused data windings (e.g.  172 B and  172 C) and corresponding cores  174 B and  174 C) would be omitted and the signal paths be connected to form a circuit. Similarly, additional data coupling to other secondary phase wires (e.g.  162 B and  162 C) is provided according to the present invention via additional series-connected corresponding windings  164 B and  164 C coupled by cores  166 B and  166 C. Furthermore, further alternate embodiments include parallel and series-parallel connected data windings (not shown). 
         [0014]    Additional embodiments include a filter  180  disposed between the primary-side data windings (e.g.  172 A,  172 B,  172 C) and secondary-side data windings (e.g.  164 A,  164 B and/or  164 C) to provide a desired band-pass, band-reject, high-pass, low-pass, etc. control of data transferred in either or both directions, or differently in each direction. Moreover, according to further alternate embodiments, the filter  180  parameters may be set and/or dynamically adjusted by data signals via connection  182  received with the data winding(s) as introduced by the data equipment  100  or other corresponding equipment disposed in other units. 
         [0015]    A further alternate embodiment includes a “Y”-to-“Y” 480-to-120/208 Vac step-down transformer  190  shown in  FIG. 3  typically located at the end-user&#39;s location, such as in the building and/or at each unit  62 ,  64  and  66  which receives a “Y” (4-wire) primary feed  58 , such as from the pole transformer  56 , which in this embodiment receives a “Δ” pole-to-pole primary feed, but delivers a “Y” step-down drop at 480 Vac to the next set of transformers  72 ,  74  and  76 , which may comprise the exemplary transformer  190 . The transformer and the related data link circuitry according to one embodiment of the present invention is substantially the same as provided for the transformer  150  shown in  FIG. 2  and discussed above, with an exception being that the transformer  190  primary windings  154 A,  154 B and  154 C are connected in a “Y” configuration to 3-phase leads  192 A,  192 B,  192 C and neutral connection  192 N, such that the data signals from the windings  172 A,  172 B and  172 C are coupled to the 3-phase leads  192 A,  192 B and  192 C. As with the prior embodiments, two such transformers having primary windings connected together to a common feed (e.g.  58 ) in the same or different locations will provide a data path from a secondary of one such transformer to the secondary of the second transformer, such as in adjacent units  64  and  66 . 
         [0016]    Other equipment such as distribution panels and circuit breakers are effectively included in the distribution layout but not shown, and are assumed to be in a closed-circuit (“on”) state for the circuits illustrated with no impedance to data transfer therethrough. Further modifications and substitutions made by one of ordinary skill in the art are within the scope of the present invention which is not to be limited, except by the claims which follow.