Patent Publication Number: US-8531262-B2

Title: Multi-site spare 3-phase transformer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application a divisional of and claims priority to U.S. patent application Ser. No. 10/175,888, filed Jun. 21, 2002 now U.S. Pat. No. 6,874,224, entitled METHOD OF MANUFACTURING A MULTI-SITE SPARE 3-PHASE TRANSFORMER, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OP THE INVENTION 
     The present invention relates generally to a transformer. More particularly, the present invention is directed to circuitry of a three-phase power transformer that is configurable to accommodate a delta or a wye connection on a supply and a load side of the transformer. Further, the present invention is directed to a three-phase transformer that can step up or step down the supply voltage to a user-selectable amount. 
     BACKGROUND OF THE INVENTION 
     Most electricity is produced at a power plant. When the electricity leaves the power plant, it is sent over high power transmission lines. Because electricity loses some of its strength, i.e., voltage, as it travels, it may be helped along to its destination by a transformer which will increase (i.e., step up) the voltage that it receives. 
     When the electricity gets closer to where it will be consumed, another transformer will be utilized to decrease (i.e., step down) the voltage that it receives before forwarding to a consumer. 
     Difficulty arises when a transformer at a substation along the distribution path from the power plant to the consumer breaks down. When a failure occurs a replacement/spare transformer is utilized to restore power. However, the replacement transformer has to meet the design requirements of the substation in need. 
     A transformer is typically designed to accommodate the layout of a particular substation. The layout from one substation to another will vary according to the electrical connections required to connect the transformer to a supply and a load. The electrical connections to the supply and the load may be via a delta connection or a wye connection. Accordingly, there are four connection configuration combinations i.e., a delta-delta, a wye-wye, a delta-wye, or a wye-delta that a substation in need could require to connect the transformer to a supply and, respectively a load. 
     Whether a transformer operates as a step up transformer or a step down transformer may also vary from one substation to another, and thus, the output voltage required from a transformer may also vary from one substation to another. Transformers have been developed to accommodate various supply and load connection configurations or various output voltage requirements. However, a transformer that has circuitry that allows a user flexibility in selecting both the supply and load connection configurations and the desired output voltage is desirable. 
     Because of the various possible supply and load connection configurations, and the various possible output voltages that a substation may require, it is costly for an electric company to maintain a replacement transformer for every possible transformer configuration. Typically, electric companies maintain transformers in inventory for utilization as replacement transformers. However, a transformer design is often unique, and thus, a transformer may not be available that is compatible with the specific requirements of the substation in need. As a result, a power outage is often extended until a suitable replacement is found. 
     Accordingly, there is a need for a spare transformer that is user-configurable to accommodate four supply and load connection configurations, and multiple output voltages. 
     SUMMARY OF THE INVENTION 
     In an aspect of the present invention, a three-phase transformer circuit is provided that includes a supply side, wherein the supply side is selectably configurable between a delta connection and a wye connection at a time of use; a load side, wherein the load side is selectably configurable between a delta connection and a wye connection at the time of use, and wherein an output voltage from the supply side is user-selectable, from multiple output voltages, at the time of use. 
     In another aspect of the present invention, a three-phase transformer circuit is provided that includes a supply side, a means for selectably configuring the supply side between a delta connection and a wye connection at a time of use, a load side, a means for selectably configuring the load side between a delta connection and a wye connection at the time of use, and a means for selecting a voltage output, from multiple voltage outputs, at the time of use, wherein the voltage output is from the load side. 
     In yet another aspect of the present invention, a method for manufacturing a multi-site transformer is provided that includes dividing the circuitry into a supply side and a load side, connecting a winding start lead from each of three sets of supply windings, individually, to one of three supply terminal boards for connecting the three sets of windings in one of a delta and a wye configuration, dividing outer windings on the supply side into a top portion and a bottom portion, and connecting a start lead and a finish lead from both the top portion and the bottom portion to the supply terminal board for controlling a voltage output from the circuitry. 
     There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of the circuitry of a multi-site three-phase transformer in accordance with the present invention. 
         FIG. 2  is a flow chart of a method for manufacturing circuitry of a multi-site three phase transformer in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
     Referring now to  FIG. 1 , wherein like reference numerals indicate like elements, circuitry  10  of a multi-site three-phase transformer in accordance with the present invention is shown. In an exemplary embodiment of the present invention, the circuitry  10  is user-configurable to accommodate multiple output voltage requirements, and multiple delta-wye connection configuration combinations for connecting the circuitry  10  to a supply and to a load. 
     The circuitry  10  has a supply/input voltage side  12  and a load/output voltage side  14 . The supply side  12  of the transformer has three supply set of windings  16 ,  18 ,  20 . Each supply set of windings  16 ,  18 ,  20  has outer windings  22 ,  24 ,  26  and inner windings  28 ,  30 ,  32 . Each of the inner windings  28 ,  30 ,  32  are optionally includable in the circuitry  10  via a start/inner winding terminal board  34 ,  36 ,  38 . In an exemplary embodiment of the present invention a non-linear device  27 ,  29 ,  31  is connected across each of the inner windings  28 ,  30 ,  32  to protect the transformer circuitry  10  from charge that accommodates on the inner windings  28 ,  30 ,  32  during the time when the inner windings  28 ,  30 ,  32  are not included in the operation of the circuitry  10 . 
     Each assembly of outer windings  22 ,  24 ,  26  is divided into a first portion  40 ,  42 ,  44  and a second portion  46 ,  48 ,  50  that can be connected to each other in series or in parallel. Tap leads  51 - 84  extend from the outer windings  22 ,  24 ,  26  and allow a user to select a potion of the outer windings  22 ,  24 ,  26 , from zero to the maximum number of windings present, that will operate in the circuitry  10 . 
     A supply terminal board  86 ,  88 ,  90  is provided at each supply set of windings  16 ,  18 ,  20 . Individually, each supply terminal board  86 ,  88 ,  90  allows the start lead  92 ,  94 ,  96  and the finish lead  98 ,  100 ,  102  of each first portion  40 ,  42 ,  44  to be connected in series or in parallel with the start lead  104 ,  106 ,  108  and the finish lead  110 ,  112 ,  114  of each second portion  46 ,  48 ,  50 . 
     Collectively, the terminal boards  86 ,  88 ,  90  are utilized to electrically connect the start leads  116 ,  118 ,  120  and finish leads  122 ,  124 ,  126  of each supply set of windings  16 ,  18 ,  20  in either a delta configuration or a wye configuration. In an exemplary embodiment of the present invention, supply connection leads  128 ,  130 ,  132  extend from the supply side  12  of the circuitry  10  to connect an incoming supply to the supply side  12  of the circuitry  10 . It should be understood by one of ordinary skill in the art that the finish lead  110 ,  112 ,  114  of each second portion  46 ,  48 ,  50  may be formed continuously with the finish lead  122 ,  124 ,  126  of each supply set of windings  16 ,  18 ,  20  and/or the supply connection lead  128 ,  130 ,  132  of each supply set of windings  16 ,  18 ,  20 . 
     Shown in  FIG. 1 , the start leads  116 ,  118 ,  120  and finish leads  122 ,  124 ,  126  of each supply set of windings  16 ,  18 ,  20  are electrically connected in a delta configuration. The start leads  116 ,  118 ,  120  each emanate from one of the supply terminal boards  86 ,  88 ,  90 . Connections  117 ,  119  and  121  also emanate from the supply terminal boards  86 ,  88 ,  90  and, in an exemplary embodiment of the present invention, are utilized to connect the three sets of windings  16 ,  18 ,  20  in the delta configuration shown in  FIG. 1 . 
     It should be understood by one of ordinary skill in the art, that three connections are made between the first, second, and third set of windings to form a delta configuration. The connections between the windings are as follows: the start lead of the first set of windings is connected to the finish lead of the third set of windings, the finish lead of the first set of windings is connected to the start lead of the second set of windings, and the finish lead of the second set of windings is connected to the start lead of the third set of windings. 
     The connections between the windings  16 , 18 , 20  to form a delta configuration are as follows: the start lead  116  of the first set of windings  16  is connected to the finish lead  126  of the third set of windings  20  via connection  117 ; the finish lead  122  of the first set of windings  16  is connected to the start lead  118  of the second set of windings via connection  119 ; and the finish lead  124  of the second set of windings  18  is connected to the start lead  120  of the third set of windings  20  via connection  121 . 
     It should be understood by one of ordinary skill in the art that to form a wye configuration the first, second and third sets of windings are connected to a neutral point. 
     To form the windings  16 ,  18 ,  20  in a wye configuration, start leads  116 ,  118 ,  120  of each supply set of windings  16 ,  18 ,  20  are connected, via an electrical connection, to the neutral line  134  on each terminal board  86 ,  88 ,  90 . 
     In one embodiment of the present invention, the neutral line  134  is connected to ground. It should also be understood by one of ordinary skill in the art that the neutral line  134  is not necessary to electrically connect each supply set of windings  16 ,  18 ,  20  in a wye configuration. 
     On the load/output voltage  14  side of the circuitry  10 , a first load terminal board  135  is utilized to connect the start leads  136 ,  138 ,  140  and finish leads  142 ,  144 ,  146  of a first set of load windings  148 ,  150 ,  152  in a delta configuration or a wye configuration for connection to a first load. 
     In an exemplary embodiment of the present invention start leads  136 ,  138 ,  140  are connected to the corresponding terminals  136 ′,  138 ′,  140 ′ on the first load terminal board  135 . The finish leads  142 ,  144 ,  146  are connected to the corresponding terminals  142 ′,  144 ′,  146 ′ on the first load terminal board  135 . 
     When it is desirable to form the first set of load windings  148 ,  150 ,  152  in a delta configuration, connections have to be made between the first, second and third sets of windings as defined above. Accordingly, a separate electrical conductor, such as a wire, is utilized to make an electrical between terminal  136 ′ and terminal  146 ′, terminal  142 ′ and terminal  138 ′, and terminal  144 ′ and terminal  140 ′. 
     In another exemplary embodiment of the present invention, when it is desirable to form the first set of load windings  148 ,  150 ,  152  in a wye configuration, terminals  136 ′,  138 ′,  140 ′ are each connected to neutral line  160 . In an exemplary embodiment of the present invention, the neutral line  160  is connected to ground. It should be understood by one of ordinary skill in the art that the neutral line  160  is not essential to electrically connect the first set of load windings  148 - 152  in a wye configuration. 
     A substation may be designed to output a voltage to two loads. Thus, in an exemplary embodiment of the present invention, a second set of load windings  154 ,  156 ,  158  are provided to electrically connect the second set of load windings  154 ,  156 ,  158  to the second load in a delta configuration or a wye configuration. 
     Shown in  FIG. 1 , the second set of windings  154 ,  156 ,  158  is electrically connected in a delta configuration as described above, that is fixed. It should be understood by one of ordinary skill in the art that the second set of windings  154 ,  156 ,  158  may be connected wye configuration, as defined above, that is fixed. Load connection leads  162 ,  164 ,  166  extend from the first set of load windings  148 ,  150 ,  152  of the circuitry  10  to connect the first set of load windings,  148 ,  150 ,  152  for a load. 
     In an exemplary embodiment of the present invention, a second load terminal board may be provided that may be utilized, as the first load terminal board  135  is utilized, that allows the second set of load windings  154 - 158  to be connected in either a delta configuration or a wye configuration. 
     Load connection leads  168 ,  170 ,  172  extend from the second set of load windings  154 ,  156 ,  158  of the circuitry  10  to connect the second set of load windings  168 ,  170 ,  172  to a load. 
     The circuitry  10  in accordance with the present invention provides a user with the option to select a voltage, among multiple voltages, to be output from the circuitry  10 . Accordingly, a user of circuitry  10  in accordance with the present invention can decide whether the circuitry  10  will be utilized to step up the voltage that the circuitry  10  receives or to step down the voltage that the circuitry  10  receives by controlling the number of windings that will be included during the operation of the circuitry  10 . 
     A user of the circuitry  10  in accordance with the present invention selects an input voltage to be received by the supply side of the transformer from multiple input voltages, and controls the output voltage from the circuitry  10  by selectively including the inner windings  28 ,  30 ,  32 , by selectively connecting the first portion  40 ,  42 ,  44  and the second portion  46 ,  48 ,  50  of each supply set of windings  16 ,  18 ,  20  in series or in parallel, and/or by selectively tapping into a the outer windings  22 ,  24 ,  26 . 
     In an exemplary embodiment of the present invention shown in  FIG. 1 , start leads  174 ,  176 ,  178  and finish leads  180 ,  182 ,  184  of each of the inner windings  28 ,  30 ,  32  respectively terminate on the start/inner winding terminal boards  34 ,  36 ,  38 . Each of the start leads  92 ,  94 ,  96  of the first portion.  40 ,  42 ,  44  also terminate on the respective start/inner winding terminal board  34 ,  36 ,  38 . Accordingly, each of the inner windings  28 ,  30 ,  32  can be electrically connected in series with the corresponding first portion  40 ,  42 ,  44 , when selectively included in the operation of the circuitry  10 . Because the start lead  116 ,  118 ,  120  of each supply set of windings  16 ,  18 , 20  also terminates on the start/inner winding terminal board  34 ,  36 ,  38 , an open circuit can be easily created between the start leads  174 ,  176 ,  178  and finish leads  180 ,  182 ,  184  of the inner windings  28 ,  30 ,  32  and the outer windings  22 ,  24 ,  26  to selectively exclude the inner windings  28 ,  30 ,  32  from operation in the circuitry  10 . 
     Further, the start lead  116 ,  118 ,  120  of each supply set of windings  16 ,  18 ,  20  emanates from each of the inner winding terminal boards  34 ,  36 ,  38  independent of whether the inner windings  28 ,  30 ,  32  are included in the operation of the circuitry  10 . Accordingly, the circuitry  10  does not have to be significantly disturbed when changing the status of the inner windings  28 ,  30 ,  32 . 
     In the same or another exemplary embodiment of the circuitry  10  of the present invention, the start leads  92 ,  94 ,  96  and the finish leads  98 ,  100 ,  102  of each first portion  40 ,  42 ,  44  and the start leads  104 ,  106 ,  108  and the finish leads  110 ,  112 ,  114  of each second portion  46 ,  48 ,  50  terminate on each of the supply terminal boards  86 ,  88 ,  90 . Accordingly, the voltage can be controlled by selectively connecting each first portion  40 ,  42 ,  44  in series or in parallel with each second portion  46 ,  48 ,  50 . In an exemplary embodiment of circuitry  10  in accordance with the present invention, the supply terminal boards are utilized to selectively configure the three sets of supply windings  16 ,  18 ,  20  in a delta or a wye configuration, and to selectively vary the output voltage from the circuitry  10 . 
     In the same or yet another exemplary embodiment of the circuitry  10  of the present invention tap leads  51 - 84  are provided that allow a user to select how many of the outer windings  22 ,  24 ,  26  will be included during the operation of the circuitry  10 . In an exemplary embodiment of the present invention, the tape leads  51 - 84  of each supply set of windings are connected to tap switches, such that when a tap switch is switched on, the voltage corresponding to the number of windings associated with the tap switch is included in the operation of the circuitry  10 . Accordingly, the taps  51 - 84  provide flexibility in attaining the specific voltage step up or step down amount. It should be understood by one of ordinary skill in the art that the number of tap leads may vary. 
     The windings of the first and/or second set of load windings  148 - 158  on the load side  14  of the circuitry  10 , in an exemplary embodiment of the present invention shown in  FIG. 1  are fixed. The supply set of windings  16 ,  18 ,  20  induce voltage into the load set of windings. Accordingly, the amount of voltage output from the windings  148 - 158  of the load side  14  is controlled by the number of windings of the supply side  12  that are selected to be included into the operation of the circuitry  10 . In an exemplary embodiment the present invention, the output voltage from the load side  14  is variable from 0 kilovolts (kV) to 338 kV. 
     In an exemplary embodiment of the present invention, any one of the terminal boards may be replaced by a switch. In an exemplary embodiment of the present invention, a delta-wye switch is utilized to selectably configure coil sets on the supply and/or load side of the transformer in either a delta or a wye configuration. In the same or another exemplary embodiment of the present invention, a voltage switch, for example a dual-voltage switch, is utilized to select a voltage that is to be, for example, output from a load side of the transformer. 
     It should be understood by one of ordinary skill in the art that the number of terminal boards of the present invention may vary. 
       FIG. 2  is a flow chart describing the steps of an exemplary method for manufacturing circuitry  10  of a multi-site three-phase transformer in accordance with the present invention. In step  186  the circuitry is divided into a supply side and a load side. A winding start lead from each of the three sets of supply windings are, individually, connected to one of three terminal boards for connecting the three sets of windings in one of a delta and a wye configuration  188 . Outer windings on the supply side are divided into a top portion and a bottom portion  190 . The start leads and finish leads from both the top portion and the bottom portion are connected to the supply terminal board for controlling a voltage output from the circuitry  192 . 
     In an exemplary embodiment of the present invention, tap leads are extended from the outer windings  194 . In the same or another exemplary embodiment of the present invention, the start lead of the top portion is connected to a start terminal board  196 . In the same or yet another exemplary embodiment of the present invention, an inner winding start lead and an inner winding finish lead of the inner windings are connected to the start terminal board  198 . 
     The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.