Abstract:
A superconducting fault current limiter includes a first superconducting module connected to an input terminal of a power system, a second superconducting module connected to an output terminal of the power system, and a connecting member interposed between the first and second superconducting modules. The first superconducting module and the second superconducting module each include two superconducting coils. The input terminal is connected to an end of the first superconducting module, and the output terminal is connected to an end of the second superconducting module. The end of the second superconducting module is disposed geometrically opposite the end of the first superconducting module.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of Korean Patent Application No. 10-2005-0044247, filed May 25, 2006, the disclosure of which is hereby incorporated herein by reference in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a superconducting fault current limiter capable of reducing a fault current in a power application field, such as a lossless power transmission line, a superconductive magnet for generating a strong or very stable magnetic field, an energy storage, a motor, a generator etc., of generating or transporting a large amount of current, and a traffic application field such as a superconducting magnetic levitation train, a superconducting propulsion ship, and so on. 
   2. Description of the Related Art 
   A superconducting fault current limiter, which is classified into an inductive type or a resistive type, is an electric power device for instantly generating impedance and sharply lowering fault current when the fault current is generated, while it is operated with a little impedance in a normal state. 
   The inductive superconducting fault current limiter limits current by mainly using an inductance component as impedance, and the resistive superconducting fault current limiter limits current by mainly using a resistance component as impedance. 
   In addition, the resistive superconducting fault current limiter generates resistance through rapid phase transition of a superconductor when a fault current is larger than a critical current of the superconducting fault current limiter, and uses the resistance as impedance to limit the fault current. 
   In particular, the resistive superconducting fault current limiter is a current limiter using a superconducting wire, which is disclosed in U.S. Pat. No. 6,275,365, entitled “Resistive Fault Current Limiter,” and U.S. Pat. No. 6,137,388, entitled “Resistive Superconducting Fault Current Limiter,” &#39;365 and &#39;388 patents employ a method of almost removing an inductance component by offsetting a magnetic flux component generated from one coil by one generated from the other coil. 
   In this manner, since the superconducting wire allows a large current to flow without loss due to zero resistance characteristics under a critical temperature, it is possible to put to practical use various types of superconducting power equipment, such as a transformer, a motor, a generator, a current limiter etc., using the superconducting wire as a superconducting coil conductor. In addition, the superconducting wire is widely used in various energy, traffic, and environmental industries applying an electric field, for example, a superconducting power storage, a superconducting power transmission cable, a superconducting magnetic levitation train, a superconducting magnetic isolation apparatus, and so on. 
   However, as shown in  FIG. 1 , the conventional resistive superconducting fault current limiters disclosed in &#39;365 and &#39;388 patents include a power input terminal IN and a power output terminal OUT, which are located at the same level, and a dielectric distance between ends of the power input and output terminals IN and OUT is very short, thereby generating disadvantages in electrical insulation. 
   That is, since most of the conventional resistive superconducting fault current limiters have a very short distance between first and final turns to which operational voltage is applied, they are inevitably vulnerable to the insulation. 
   In addition, since the conventional superconducting fault current limiters have a structure that a superconducting wire or coil  2  wound around a bobbin  1  is stacked as shown in  FIG. 2 , a temperature may be excessively increased during the phase transition, and a recovering speed of the fault current limiter may be considerably delayed until the next fault current is limited. 
   Meanwhile, U.S. Pat. No. 5,021,914, entitled “Superconducting Switch and Current Limiter Using such a Switch,” discloses another conventional resistive superconducting fault current limiter using a former made of a glass tube as well as an iron core made of cast iron. 
   However, in the case of &#39;914 patent, since a low temperature superconducting wire of stabilizer is made of a copper alloy as a main component, the stabilizer has a disadvantage of generating a very low resistance in a quench state of escaping from the superconducting state. 
   Therefore, the stabilizer of &#39;914 patent requires a very long wire. In addition, the lower temperature superconducting wire has a circular cross-section difficult to be wound around the same frame, and though the wire is wound, a somewhat magnetic leakage flux is generated to make it difficult to expect a perfect non-induction characteristic. 
   In addition, since &#39;914 patent includes the low temperature superconducting wire, liquid helium should be used as a coolant. However, when the superconducting wire is out of the superconducting state (quench), the liquid helium may be sublimated to remarkably lower insulation resistance. Further, the superconducting wire should be connected in parallel in order to increase a critical current. Nevertheless, &#39;914 patent has no structure capable of connecting the superconducting wire in parallel. 
   SUMMARY OF THE INVENTION 
   In order to solve the foregoing and/or other problems, it is an object of the present invention to provide a resistive superconducting fault current limiter capable of obtaining a higher insulation resistance, reducing a temperature increasing width, and rapidly recovering a re-cooling speed of the current limiter, by locating an input terminal and an output terminal of the current limiter opposite to each other to stabilize insulation characteristics, though using the same length as a conventional superconducting wire. 
   According to an aspect of the present invention, a resistive superconducting fault current limiter includes: a first superconducting module connected to an input terminal side of a power system to stabilize insulation characteristics; a second superconducting module connected to an output terminal to stabilize insulation characteristics; and a connecting member interposed between the first and second superconducting modules to dispose the input and output terminals connected to the first and second superconducting modules opposite to each other. 
   In one embodiment, the first superconducting module may further include a first outer bobbin having a predetermined diameter, a first wire wound on a peripheral surface of the first outer bobbin in one direction with a predetermined inclination angle, a first inner bobbin having a diameter smaller than that of the first outer bobbin and disposed in the first outer bobbin, a second wire wound on a peripheral surface of the first inner bobbin in the other direction with a predetermined inclination angle so that the second wire has a magnetic field opposite to the first wire, and a current introduction terminal for connecting the first and second wires in parallel. 
   In another embodiment, the second superconducting module may further include a second outer bobbin having a predetermined diameter, a third wire wound on a peripheral surface of the second outer bobbin in one direction with a predetermined inclination angle, a second inner bobbin having a diameter smaller than that of the second outer bobbin and disposed in the second outer bobbin, a fourth wire wound on a peripheral surface of the second inner bobbin in the other direction with a predetermined inclination angle so that the fourth wire has a magnetic field opposite to the third wire, and a current output terminal for connecting the third and fourth wires in parallel. 
   In still another embodiment, the connecting member may include a first connecting body coupled to the first outer bobbin for electrical connection of the first and fourth wires, a second connecting body coupled to the second outer bobbin for electrical connection of the second and third wires, a third connecting body disposed in the second connecting body for electrical connection of the first and fourth wires and coupled to the first connecting body and the second inner bobbin, and a fourth connecting body disposed in the first connecting body for electrical connection of the second and third wires and coupled to the second connecting body and the first inner bobbin. 
   In yet another embodiment, the first connecting body may further include a first circular ring fitted to the first outer bobbin, and a first connecting part extending from the first circular ring to guide the first wire. 
   In yet another embodiment, the second connecting body may further include a second circular ring fitted to the second outer bobbin, and a second connecting part extending from the second circular ring to guide the third wire. 
   In yet another embodiment, the third connecting body may further include a third circular ring fitted to the second inner bobbin, and a third connecting part extending from the third circular ring to guide the fourth wire and coupled to the first connecting part. 
   In yet another embodiment, the fourth connecting body may further include a fourth circular ring fitted to the first inner bobbin, and a fourth connecting part extending from the fourth circular ring to guide the second wire and coupled to the second connecting part. 
   According to another aspect of the present invention, a resistive superconducting fault current limiter includes: a bobbin having a small diameter; a first wire winding groove formed at a peripheral surface of the bobbin in one direction with a predetermined inclination angle; a second wire winding groove formed, to have a depth different from the first wire winding groove through a stepped surface in the other direction with a predetermined inclination angle; an inner wire wound in the first wire winding groove; an outer wire wound in the second wire winding groove; an insulating material formed between the inner wire and the outer wire; a current introduction terminal connecting the inner and outer wires in parallel; and a current output terminal connecting the inner and outer wires in parallel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a circuit diagram of a conventional resistive superconducting fault current limiter; 
       FIG. 2  is a view illustrating a schematic connection of a conventional wire; 
       FIG. 3  is a circuit diagram of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention; 
       FIG. 4  is an exploded perspective view of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention; 
       FIG. 5  is an assembled perspective view of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention; 
       FIG. 6  is a partial cross-sectional view of a first superconducting module in accordance with a first embodiment of the present invention; 
       FIG. 7  is a perspective view of a connecting member in accordance with a first embodiment of the present invention; 
       FIG. 8  is an exploded perspective view of a connecting member in accordance with a first embodiment of the present invention; 
       FIG. 9  is an assembled perspective view of a connecting member in accordance with a first embodiment of the present invention; 
       FIG. 10  is a schematic view illustrating connection of first and second superconducting modules in accordance with a first embodiment of the present invention; 
       FIG. 11  is a simulation screen illustrating distribution of a magnetic field in a space of a superconducting module in accordance with a first embodiment of the present invention; 
       FIG. 12  illustrates a bobbin having a dual wire winding groove in accordance with a second embodiment of the present invention; 
       FIG. 13  is a schematic cross-sectional view of  FIG. 12  illustrating a state that a plurality of wires are wound around one bobbin in accordance with a second embodiment of the present invention; 
       FIG. 14  is a circuit diagram for a current limiting test of a resistive superconducting fault current limiter in accordance with a second embodiment of the present invention; 
       FIG. 15  is a current waveform of a test result of a circuit diagram of  FIG. 14 ; 
       FIG. 16  is a current distribution waveform of a test result of a circuit diagram of  FIG. 14 ; and 
       FIG. 17  is a resistance measurement waveform of a test result of a circuit diagram of  FIG. 14 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     FIG. 3  is a circuit diagram of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention,  FIG. 4  is an exploded perspective view of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention, and  FIG. 5  is an assembled perspective view of a resistive superconducting fault current limiter in accordance with a first embodiment of the present invention. 
     FIG. 6  is a partial cross-sectional view of a first superconducting module in accordance with a first embodiment of the present invention, and  FIG. 7  is a perspective view of a connecting member in accordance with a first embodiment of the present invention. 
     FIG. 8  is an exploded perspective view of a connecting member in accordance with a first embodiment of the present invention,  FIG. 9  is an assembled perspective view of a connecting member in accordance with a first embodiment of the present invention, and  FIG. 10  is a schematic view illustrating connection of first and second superconducting modules in accordance with a first embodiment of the present invention. 
   Referring to  FIGS. 3 to 10 , the resistive superconducting fault current limiter in accordance with a first embodiment of the present invention includes a first superconducting module  10 , a second superconducting module  20 , and a connecting member  30 . 
   Referring to  FIGS. 3 to 5 , the first superconducting module  10  is connected to an input terminal side of a power system (for example, a power transmission line) in order to stabilize insulation characteristics. The first superconducting module  10  includes a first outer bobbin  11 , a first wire  12 , a first inner bobbin  13 , a second wire  14 , a current introduction terminal  15 . 
   Referring to  FIG. 4 , the first outer bobbin  11  has a predetermined diameter of cylindrical shape, and the first wire  12  is wound on a peripheral surface of the first outer bobbin  11  in one direction with a predetermined inclination angle. 
   The first inner bobbin  13  has a diameter smaller than that of the first outer bobbin  11 , and is disposed in the first outer bobbin  11 , as shown in  FIG. 6 . 
   At this time, the second wire  14  having a magnetic field opposite to the first wire  12  is wound around the first inner bobbin  13 , and the winding of the second wire  14  is disposed on a peripheral surface of the first inner bobbin  13  in the other direction with a predetermined inclination angle. 
   Referring to  FIG. 3 , the current introduction terminal  15  is connected to an input terminal side of a power system, and connects the first and second wires  12  and  14  in parallel. 
   Referring to  FIGS. 4 and 5 , the second superconducting module  20  is symmetrically disposed to the first superconducting module  10  with reference to the connecting member  30 , and connected to an output terminal side of a power system in order to stabilize insulation characteristics. The second superconducting module  20  includes a second outer bobbin  21 , a third wire  22 , a second inner bobbin  23 , a fourth wire  24 , and a current output terminal  25 . 
   Referring to  FIG. 4 , the second outer bobbin  21  has a cylindrical shape with a diameter equal to the first outer bobbin  11 , and the third wire  22  is wound on a peripheral surface of the second outer bobbin  21  in one direction with a predetermined inclination angle. 
   That is, the third wire  22  is wound around the second outer bobbin  21  in the same direction as the first wire  11 . 
   Referring to  FIG. 4 , the second inner bobbin  23  has a cylindrical shape with a diameter smaller than that of the second outer bobbin  21 , namely a diameter equal to the first inner bobbin  13 . The second inner bobbin  23  is disposed in the second outer bobbin  21 . 
   The fourth wire  24  is wound on a peripheral surface of the second inner bobbin  23  to be wound in the other direction with a predetermined inclination angle so that the fourth wire  4  has a magnetic field opposite to the third wire  22 . 
   That is, the fourth wire  24  is wound around the second inner bobbin  23  in the same direction as the second wire  12 . 
   Referring to  FIG. 3 , the current output terminal  25  is connected to an output terminal side of a power system, and connects the third and fourth wires  22  and  24  in parallel. 
   Referring to  FIGS. 7 ,  8  and  9 , the connecting member  30  is disposed between the first and second superconducting modules  10  and  20  to arrange the input and output terminals of the first and second superconducting modules  10  and  20  in directions opposite to each other as shown in  FIG. 10 . The connecting member  30  includes first to fourth connecting bodies  31 ,  32 ,  33  and  34 . 
   The first connecting body  31  for electrically connecting the first and fourth wires  12  and  24  includes a first circular ring  31   a  fitted to the first outer bobbin  11 , and a plurality of first connecting parts  31   b  extending downward from the first circular ring  31   a  to guide the first wire  12 , which are integrally formed with each other. 
   The second connecting body  32  for electrically connecting the second and third wires  14  and  22  includes a second circular ring  32   a  fitted to the second outer bobbin  21 , and a plurality of second connecting parts  32   b  extending upward from the second circular ring  32   a  to guide the third wire  22 , which are integrally formed with each other. 
   The third connecting body  33  for electrically connecting the first and fourth wires  12  and  24  includes a third circular ring  33   a  that has a diameter smaller than that of the second circular ring  32   a  to be disposed in the second connecting body  32  and is fitted to the second inner bobbin  23 , and a plurality of third connecting parts  33   b  that extend upward from the third circular ring  33   a  to guide the fourth wire  24  and are coupled to the first connecting parts  31   b.    
   At this time, surface contact parts of the first and third connecting parts  31   b  and  33   b  are coupled to each other using welding or soldering. 
   The fourth connecting body  34  for electrically connecting the second and third wires  14  and  22  includes a fourth circular ring  34   a  that has a diameter smaller than that of the first circular ring  31   a  to be disposed in the first connecting body  31  and is fitted to the first inner bobbin  13 , and a plurality of fourth connecting parts  34   b  that extend upward from the fourth circular ring  34   a  to guide the second wire  22  and are coupled to the second connecting parts  32   b.    
   At this time, surface contact parts of the second and fourth connecting parts  32   b  and  34   b  may be coupled to each other using welding or soldering. 
   In addition, when the first and fourth wires  12  and  24  are guided along the first and third connecting bodies  31  and  33 , ends of the first and fourth wires  12  and  24  are connected to each other, and when the second and third wires  14  and  22  are guided along the second and fourth connecting bodies  32  and  34 , ends of the second and third wires are also connected to each other. 
   Hereinafter, operation of the first embodiment of the present invention will be described in conjunction with  FIGS. 3 to 11 . 
   First, a resistive superconducting fault current limiter in accordance with an embodiment of the present invention is connected to input and output terminal sides of a power system through a current introduction terminal  15  and a current output terminal  25 , respectively. 
   Then, when a large current, i.e., a fault current generated due to the falling of a lightning, short-circuit, and so on, is applied through the input terminal side of the power system, the fault current is reduced by generating a resistance through the phase transition of the first and second superconducting modules  10  and  20  that are symmetrical about the connecting member  30  as shown in  FIG. 10 . 
   More specifically, the first superconducting module  10  has a multi-layered structure including a first outer bobbin  11  and a first inner bobbin  13 , and the second superconducting module  20  also has a multi-layered structure including a second outer bobbin  21  and a second inner bobbin  23 . 
   When the fault current is applied to the current introduction terminal  15 , the fault current is guided to the first wire  12  of the first outer bobbin  11  and the second wire  14  of the first inner bobbin, which are connected to the current introduction terminal  15  in parallel and have winding directions opposite to each other. 
   At this time, the first wire  12  is connected to the fourth wire  24  of the second inner bobbin  23  included in the second superconducting module  20  through the first and third connecting bodies  31  and  33  of the connecting member  30 , and the second wire  14  is connected to the third wire  22  of the second outer bobbin  21  included in the second superconducting module  20  having a winding direction opposite to the fourth wire  24  through the second and fourth connecting bodies  32  and  34  of the connecting member  30 . 
   Therefore, the magnetic field represented from the first wire  12  of the first outer bobbin  11  has a direction opposite to the second wire  14  of the first inner bobbin  13 . 
   In addition, the magnetic field represented from the third wire  22  of the second outer bobbin  21  has a direction opposite to the fourth wire  24  of the first second bobbin  23 . 
   Since the module  10  and the module  20  are connected to each other by means of the connecting member  30 , the fault current limiter has the bifilar characteristics. 
   That is, since the dielectric distance between the input terminal side and the output terminal side of the current limiter of the first embodiment in accordance with the present invention is set to reach a sufficient distance, and a distance between first and final turns to which operational voltage is applied is distant. Thereby, it is possible to obtain good electrical insulation characteristics. 
   In other words, from a viewpoint of cooling, since the first and second wires  12  and  14  and the third and fourth wires  22  and  24  of the first embodiment in accordance with the present invention are connected in parallel through the current introduction terminal  15  and the current output terminal  25 , a width of increasing a temperature and a time needed to re-cool the temperature can be remarkably shorted. 
   That is, providing that the contact surface of the wires of the conventional deposited structure is neglected, a quantity of heat generated therefrom will be expressed as follows:
 
 Q =( I   2 ρ1)/ A=J ρp  1 I   [Formula 1]
 
   In this process, since a specific resistance ρ, a length l, a current density J of the parallel wires of the first embodiment in accordance with the present invention are equal to the wires of the conventional deposited structure, the quantity of heat Q is in proportion to the current  1 , i.e., Q∝I. 
   Therefore, while the current of the conventional multi-layered structure of n wires is entirely nI (Ampere, A), the current of each wire of the parallel structure of the present invention is I (A). 
   That is, since the heat quantity accumulated for the same time means that the wire deposited structure is larger than the wire parallel structure by the deposited number of times, the temperature increase of the conventional wire deposited structure is higher than that of the wire parallel structure of the first embodiment in accordance with the present invention. 
   In addition, a time that the increased temperature is lowered again to its original temperature is a time constant, which will be described as follows:
 
τ= Cρ   d   V/hS  
 
   Providing that a specific heat C, density τ d, and heat transfer efficient h are constant, the time constant τ is in proportion to a volume V and a surface area S. 
   Therefore, when the time constant τ of the conventional deposited wires and the parallel wires of the present invention is calculated using the above relationship, a time constant τ nt  of the conventional deposited wires is as the following formula 2:
 
τ nt   =ntw/ 2( nt+w )  [Formula 2]
 
   where n is the number of wires, t is a thickness of the wire, and w is a width of the wire. 
   In addition, a time constant τ 1  the parallel wires of the first embodiment of the present invention is as the following formula 3:
 
τ t   =tw/ 2( t+w )  [Formula 3]
 
   At this time, calculation of a ratio of the time constants of Formulae 1 and 2 is as the following formula 4:
 
τ nt /τ t   =n ( t+w )/( nt+w )  [Formula 4]
 
   In this process, due to characteristics of the superconducting wire, t&lt;&lt;w, and Formula 4 is expressed by the following formula 5:
 
τ nt /τ t ≈n[Formula 5]
 
   That is, the temperature decrease of the conventional deposited wires consumes a time longer than that of the parallel wires of the first embodiment of the present invention by about n times. This means that a re-operation time of the current limiter of the conventional deposited wire is longer than that of the parallel wires of the first embodiment of the present invention. 
   Meanwhile,  FIG. 11  illustrates a simulation result that the first and second superconducting modules  10  and  20  of the current limiter are simulated in axial symmetry using an FEM tool, representing a magnetic field existing in a space. 
   Referring to  FIG. 11 , it will be appreciated that the magnetic field in the first and second superconducting modules  10  and  20  of the first embodiment of the present invention is about “0.” This means that about 0.02 T of magnetic field (magnetic leakage flux) is generated between the outer coil and the inner coil. 
   In addition, it will be appreciated that a magnetic energy is 0.066J, and a inductance is about 12 μH by calculating the inductance using the magnetic energy equation. 
   Providing that the first embodiment of the present invention uses 16 current limiters, all of the current limiters have about 0.2 mH of inductance, which is corresponding to about 0.07 Ω of resistance. 
   Meanwhile, since the magnetic leakage flux generated between the outer coil and the inner coil is very small, most of the superconducting alternate current loss is a loss due to the transmission current. Calculating the magnetic leakage flux using the following formula 6, the Norris equation, the magnetic leakage flux P sf  is about 0.06 W/m, and the magnetic leakage flux of all the current limiters is about 54.78 W.
 
 P   sf =( fμ   0   I   2   c /2π S   f )×(2(1 −i   m )× LN (1− i   m )+2 i   m   −i   2   m )[ W/m]   [Formula 6]
 
   I c : critical current density f: frequency S f : space factor 
   i m : ratio of critical current vs applied current 
   μ 0 : permeability in air representing magnetic susceptibility of air 
   LN: natural log 
     FIGS. 12 and 13  illustrate a second embodiment of the present invention, showing a plurality of wires parallelly connected to one bobbin. 
   That is, the second embodiment of the present invention includes the plurality of wires wound around the one bobbin, rather than using the connecting member of the first embodiment. 
   The current limiter of the second embodiment includes a bobbin  41  having a predetermined diameter, a first wire winding groove  42  formed on a peripheral surface of the bobbin  41  in one direction with a predetermined inclination angle, a second wire winding groove  43  formed to have a depth different from the first wire winding groove  42  through a stepped surface in the other direction with a predetermined inclination angle, an inner wire  44  wound in the first wire winding groove  42 , an outer wire  45  wound in the second wire winding groove  43 , an insulating material (not shown) formed between the inner wire  44  and the outer wire  45 , a current introduction terminal (not shown) and a current output terminal (not shown) connecting the inner and outer wires  44  and  45  in parallel. 
   In this process, the first and second wire winding grooves  42  and  43  formed in the bobbin  41  is shown to have a different width for the convenience of understanding, but have the same width in real. 
   That is, the first and second wire winding grooves  42  and  43  have the same width, and the inner and outer wires  44  and  45  of the same width are wound in the grooves  42  and  43 , respectively. 
   As described above, while the first embodiment of the present invention has the structure that a plurality of wires are respectively wound around the plurality of bobbins in different directions, and then, the plurality of bobbins are symmetrically arranged through the connecting member in parallel, the second embodiment of the present invention has the structure that a plurality of wires are wound around one bobbin in different directions, and then, they are parallelly connected to each other, operation of which is the same as the first embodiment. Hereinafter, the description overlapping the first embodiment will be omitted. 
   In the second embodiment of the present invention, as a result of measuring inductance at a cryogenic temperature after manufacturing the resistive superconducting fault current limiter including a inner diameter 98 mm of bobbin having inner and outer layers on which 8.7 m of wires are respectively wound, it has been confirmed that the measured value of the inductance is less than 0.5 μH, and excellent non-induction characteristics can be obtained. 
   That is, as a result of performing a short circuit test of a current limiting module including constituting a circuit as shown in  FIG. 14  for the short circuit test, applying current to an AC power supply up to 150V, operating a fault controller to generate a fault current for about 0.1 second, and performing a test for recovering the fault, it has been confirmed that the current is limited at about 1600 A peak  when the resistive superconducting fault current limiter is used, while at least several kA may generate the fault current when the resistive superconducting fault current limiter is not used, as shown in  FIG. 15 . 
   In addition, as can be seen from the test result of  FIG. 16 , the current is uniformly distributed at about 1:1 of a current distribution ratio between the inner and outer layers, and as shown in  FIG. 7 , as a result of measurement of resistance generated due to the fault current, the resistance is instantly generated to about 0.02 Ω to limit the fault current, and then, the resistance is rapidly increased up to about 0.045 Ω. Entirely reviewing the test results, it will be appreciated that the resistive superconducting fault current limiter in accordance with the present invention has excellent resistive characteristics. 
   In accordance with the present invention, after the inner bobbin is disposed in the outer bobbin, the wires are wound around the inner and outer bobbins to be connected through the current introduction terminal in directions opposite to each other to thereby constitute the superconducting module, and the module is symmetrically formed through the connecting member, thereby completing the current limiter. Therefore, it is possible to obtain the following effects. 
   First, it is possible to obtain a higher insulation resistance by locating an input terminal and an output terminal of the current limiter opposite to each other to stabilize insulation characteristics, though using the same length as a conventional superconducting wire. 
   Second, it is possible to reduce a temperature increasing width, and rapidly recovering a re-cooling speed of the current limiter. 
   Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.