FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A modular rod type resistive superconductor fault current limiter equipment and assembly
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company; AND
Centra] Power Research Institute (CPRI), Prof Sir C.V. Raman Road, P.B. No: 8066; Sadasiva Nagar Post Office, Bangalore 560 080, Karnataka, an autonomous society under Ministry of Power, Government of India.
INVENTORS
Dixit Manglesh, Lobo Anthony Marcel, Kulkarni Sandeep and Sukali Ramesh, all of Crompton Greaves Limited, Medium Voltage Product Technology Centre (MVPTC), Global R&D Centre, Kanjurmarg (East), Mumbai - 400042, Maharashtra, India; all Indian Nationals.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
This invention relates to the field of electrical and electronic components and assemblies.
Particularly, this invention relates to a current Jimiter.
More particularly, this invention relates to a superconductor fault current limiter.
Specifically, this invention relates to a modular rod type resistive superconductor fault current limiter equipment and assembly.
BACKGROUND OF THE INVENTION:
A Fault Current Limiter (FCL) is a device which limits the prospective fault current when a fault occurs in a power transmission and distribution network. It serves to limit mechanical, thermal, and electrical stresses applied to mechanical and electrical components of an electric power system when a fault current such as a short circuit, a ground fault, and a lightning strike occurs.
Current limiting devices are critical in electric power transmission and distribution systems. A current limiter is designed to react and absorb unanticipated power disturbances in a utility grid, preventing loss of power to customers or damage to utility grid equipment.

The concept of using the superconductors to carry electric power and to limit peak currents has been around since the discovery of superconductors and the realization that they possess highly non-linear properties. More specifically, the current limiting behavior depends on their nonlinear response to temperature, current and magnetic field variations. Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature,
The superconducting fault current limiter may be of an inductive type or of a resistive type. In a resistive FCL, the current passes through the superconductor and when a high fault current begins, the superconductor quenches: it becomes a normal conductor and the resistance rises sharply and quickly. This transition of a superconductor from its superconducting state to a normal resistive state is termed "quenching."
Superconductors, especially high-temperature superconducting (HTS) materials, are well suited for use in a current limiting device because of their intrinsic properties that can be manipulated to achieve the effect of "variable impedance" under certain operating conditions.
FCLs would be installed in transmission and distribution systems for electric utilities and large energy users in high-density areas. The benefits include increased safety, increased reliability, improved power quality, compatibility with existing protection devices, greater system flexibility from adjustable maximum allowed current, and reduced capital investment because of deferred upgrades. The superconducting FCL provides the same continuous

protection, with no standby energy losses due to joule heating and no voltage drop. The superconducting FCL instantaneously limits the flow of excessive current by allowing itself to exceed its superconducting transition temperature and switch to a purely resistive state, thus minimizing the fault current that passes through it. It takes less than 2ms in detecting and limiting the fault currents.
Generally resistive SFCL are manufactured by bulk superconductors or coils of superconductor tapes. The bulk superconductor modules are fragile and are prone to damages. Also the assembly becomes bulky. HTS coils for this application have inductive effects and cannot be non-inductively wound for higher voltages. Making non-inductively coils are complicated and space consuming. This makes the SFCL configuration bulky and complicated for assembly.
However, there is a need for a SFCL which is modular and is very simple and compact.
Also, prior art SFCLs are coil type in which if the superconducting coil gets damaged during surge, the entire coil needs to be replaced. Superconducting material is expensive, and hence entire replacement is a costly proposition. There is a need for an SFCL which is relatively inexpensive in terms of replacement of superconductor material.
A resistive type superconductor fault current limiter is an intelligent and self acting device that can detect and limit fault currents level up to 80% in very

short duration. It operates and limits the current within the quarter of first cycle of the fault (within 1 or 2 ms). It is invisible to the line during nominal operations and does not add reactive power losses to the system.
In today's power scenario, the generating capacity is rapidly increasing and is added in to the power systems with many interconnections. The addition of new generation and expansion of power network, has led to the threat of significant increase in fault current levels. The increase in fault current could surpass the breaking capacity of the installed circuit breakers. Conventional solutions such as bus splitting, fuses, upgradation of circuit breaker and downstream equipments, reactors and the like are available. However, they are not regarded as effective measures when reliability, stability and sustainability of power systems are considered.
Conventional solutions to cope with the fault currents also add more reactive power to the system during normal operation. Upgradation or replacement of the breakers and related downstream equipments would be expensive, time consuming and could lead to power cut for several days, affecting the economy growth.
There is a need for a smart engineering solution which is effective, reliable, and economical and maintenance free.
OBJECTS OF THE INVENTION:
An object of the invention is to provide a resistive superconductor fault current limiter.

Another object of the invention is to provide a modular type resistive superconductor fault current limiter.
Yet another object of the invention is to provide a coil free compact modular type resistive superconductor fault current limiter.
Still another object of the invention is to provide a modular assembly design for a superconductor fault current limiter which is compatible for all possible current and voltage rating.
An additional object of the invention is to provide a superconductor fault current limiter with relatively higher efficiency.
Yet an additional object of the invention is to provide a superconductor fault current limiter wherein effect of flux impact between modules is minimized
significantly.
Still an additional object of the invention is to provide a superconductor fault current limiter with relatively fast current limitation capability.
Another additional object of the invention is to provide a superconductor fault current limiter with ease of manufacturing and assembly.

SUMMARY OF THE INVENTION:
According to this invention, there is provided a modular rod type resistive superconductor fault current limiter equipment, said equipment comprises: i, a poly-sided elongate (rod shaped) substrate adapted to host a plurality of strips of superconductors which are axially aligned, such that there is at least one superconductor strip along one side of the poly-sided substrate, said strips being parallel to one another in a spaced apart manner due to the nature of the polygon; ii. plurality of operative horizontal contacts, each contact adapted to connect to a superconductor strip on each side of said poly-sided rod, said operative horizontal contacts being located at axial ends of said rod such that said strips terminate on said operative horizontal contacts, said operative horizontal contacts consisting of a first set of horizontal contacts and a second set of horizontal contacts, wherein said first set of horizontal contacts are adapted to connect to respective strips on a first axial end and wherein said second set of horizontal contacts are adapted to connect to respective strips on a second opposite axial end such that each strip terminates at one horizontal contact from a first set of contacts and a second horizontal contact from a second set of contacts; and iii. at least a first end vertical terminal adapted to be connected to said first set of operative horizontal contacts in order to provide external connections and a second end vertical terminal adapted to be connected to said second set of operative horizontal contacts to provide external connections.

Typically, said strips are high-temperature superconductivity (HTS) tapes.
Typically, said substrate is a Glass Fiber Reinforced Polymer (GFRP) plate or rod.
Typically, breadth "width" of the strips range from about 4mm to about
12mm.
Typically, said contacts are copper horizontal end terminals.
According to this invention, there is also provided a modular rod type resistive superconductor fault current limiter assembly, said assembly comprises:
A. a plurality of rod type resistive superconductor fault current limiter
equipment of claim 1, each rod having a pair of end vertical terminals;
and
B. an assembly for stacking a plurality of said equipment together, in a
spaced apart manner, to provide modular rating by adding or
removing said equipment, said assembly further comprising:
a. first end plate and an axially spaced apart second end plate wherein said first end plate is an operative top plate and said second end plate is an operative bottom plate with said plurality of stacked rods being aligned longitudinally (axially) in the spaced apart region between aid first end plate and said second end plate.

Typically, said first end plate includes slots such that the end vertical terminals of each rod protrude beyond the plane of the end plate to allow further electrical connections.
Typically, said assembly includes a third end plate operatively below said second end plate which is mechanically coupled to said first end plate by means of tie rods disposed therebetween, thus ensuring pre-defined space and a robust assembly.
Typically, said top plate is a GFRP plate
Typically, said bottom plate is a GFRP plate
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates a schematic of a single rod-type resistive superconductor fault current limiter equipment;
Figure 2 illustrates a front view of a multiple rod assembly using the equipment of Figure 1;
Figure 3 illustrates an auxiliary view of the assembly of Figure 2; and

Figure 4 illustrates a schematic view of the assembly of Figure 2 immersed in a cryostat chamber.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided a modular rod type resistive superconductor fault current limiter.
Figure 1 illustrates a schematic of a single rod-type resistive superconductor fault current limiter equipment (10).
In accordance with an embodiment of this invention, there is provided a poly-sided elongate (rod shaped) substrate (1) upon which a plurality of strips (4) of superconductors are axially aligned, i.e. along the axis of the elongate substrate, such that there is at least one superconductor strip along one side of the poly-sided substrate. The poly-sided substrate is such that it has sides more than 2. The strips are parallel to one another in a spaced apart manner due to the nature of the polygon. The strips are high-temperature superconductivity (HTS) tapes. The substrate is a Glass Fiber Reinforced Polymer (GFRP) substrate.
The breadth "Width" of the HTS strips may range from about 4mm to about 12mm.
In accordance with another embodiment of this invention, there are provided a plurality of operative horizontal contacts (3), each contact adapted to

connect to a superconductor strip on each side of the poly-sided rod. The operative horizontal contacts are located at axial ends of the rod such that the strips (4) terminate on the operative horizontal contacts (3). These contacts (3) are copper horizontal end terminals. These set of contacts lie within the perimeter defined for each side of the rod, and form the axial edge of the rod, without extending beyond its boundaries.
Superconducting material is brittle. The incoming surge, which it should withstand, is a relatively high surge, typically about 10 to 20 times the normal current. The cost of superconducting material is high. Hence, even if it formed into coils, the coil damages, and replacement of coil turns out to be a substantially expensive affair. In the current invention, only a portion (strip) of the superconducting material (on any side of the poly-sided rod) may get damaged. Thus, only the strip will have to be replaced, without affecting the adjacent strips, or the substrate, in general.
Depending upon the rating required, the number of sides to the poly-sided rod may be defined, thereby increasing the number of strips.
In accordance with yet another embodiment of this invention, there is provided at least an end vertical terminal (2) adapted to be connected to the operative horizontal contacts (3) in order to provide external connections.
Figure 2 illustrates a front view of a multiple rod assembly using the equipment of Figure 1.

In accordance with still another embodiment of this invention, there is provided an assembly for stacking a plurality of rods (Figure 1) together to provide increased rating to a superconductor fault current limiter (SFCL). Adjacent rods are spaced apart with respect to each other.
Figure 3 illustrates an auxiliary view of the assembly of Figure 2.
In accordance with an additional embodiment of this invention, there is provided a first end plate (5) and an axially spaced apart second end plate (6) wherein the first end plate is an operative top GFRP plate and the second end plate is an operative bottom GFRP plate. The plurality of stacked rods (10), as seen in Figure1, are aligned longitudinally (axially) in the spaced apart region between the first end plate (5) and the second end plate (6). Adjacent plates are spaced apart with respect to each other. The first end plate (5) includes slots such that the end vertical terminals (2) of each rod protrude beyond the plane of the end plate to allow further electrical connections.
In accordance with yet an additional embodiment of this invention, there is provided a third end plate (7) operatively below said second end plate which is mechanically coupled to the first end plate (5) by means of tie rods (8) disposed therebetween, thus ensuring pre-defined space and a robust assembly.
The technical advancement lies in providing a coil free compact assembly for resistive type superconductor fault current limiter. It also provides for a

modular assembly design, compatible for a plurality of possible current and voltage ratings; just by increasing or removing the rod modules, various type of current and voltages ratings can be achieved. The spaces between the HTS strips provide for cooling channels and hence, higher efficiency due to cooling channels can be achieved. Every conductor surface is exposed to cryogenic fluid for effective cooling. Using this assembly, fast current limitation (1-2 ms) can be achieved. The non-inducting and coil free assembly is achieved due to parallel arrangement of conductors. The parallel arrangement in a module will have no effect of flux from other module. There is also provided an optimized design for HTS tapes performing live without damage or burnout. It is, therefore, a compact modular design for any rating of current or voltage. And it is easy for manufacturing and assembly.
Figure 4 illustrates a schematic view of the assembly of Figure 2 immersed in a cryostat chamber.
A multiple rod assembly (10) is immersed in a cryostat chamber (30) having liquid nitrogen (28) and is covered by a cryostat top flange (21). A liquid nitrogen inlet (22) facilitates entry of liquid nitrogen into the cryostat chamber. Reference numeral 23 refers to nitrogen gas vent of the cryostat chamber. Copper current leads (24) extend from the multiple rod assembly (10) out of the cryostat chamber. Reference numeral 25 refers to a lever sensor. Reference numeral 26 refers to a temperature sensor. Reference numeral 27 refers to a pressure release valve. The cryostat chamber is a

double layered chamber with vacuum (29) in between the doubled layered walls of the chamber.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A modular rod type resistive superconductor fault current limiter equipment, said equipment comprising:
i. a poly-sided elongate (rod shaped) substrate adapted to host a plurality of strips of superconductors which are axially aligned, such that there is at least one superconductor strip along one side of the poly-sided substrate, said strips being parallel to one another in a spaced apart manner due to the nature of the polygon;
ii. plurality of operative horizontal contacts, each contact adapted to connect to a superconductor strip on each side of said poly-sided rod, said operative horizontal contacts being located at axial ends of said rod such that said strips terminate on said operative horizontal contacts, said operative horizontal contacts consisting of a first set of horizontal contacts and a second set of horizontal contacts, wherein said first set of horizontal contacts are adapted to connect to respective strips on a first axial end and wherein said second set of horizontal contacts are adapted to connect to respective strips on a second opposite axial end such that each strip terminates at one horizontal contact from a first set of contacts and a second horizontal contact from a second set of contacts; and iii. at least a first end vertical terminal adapted to be connected to said first set of operative horizontal contacts in order to provide external connections and a second end vertical terminal adapted to be connected to said second set of operative horizontal contacts to provide external connections.

2. An equipment as claimed in claim 1 wherein, said strips are high-temperature superconductivity (HTS) tapes.
3. An equipment as claimed in claim 1 wherein, said substrate is a Glass Fiber Reinforced Polymer (GFRP) plate or rod.
4. An equipment as claimed in claim 1 wherein, breadth "width" of the strips range from about 4mm to about 12mm.
5. An equipment as claimed in claim 1 wherein, said contacts are copper horizontal end terminals.
6. A modular rod type resistive superconductor fault current limiter assembly, said assembly comprising:
A. a plurality of rod type resistive superconductor fault current limiter
equipment of claim 1, each rod having a pair of end vertical terminals;
and
B. an assembly for stacking a plurality of said equipment together, in a
spaced apart manner, to provide modular rating by adding or
removing said equipment, said assembly further comprising:
a. first end plate and an axially spaced apart second end plate wherein said first end plate is an operative top plate and said second end plate is an operative bottom plate with said plurality of stacked rods being aligned longitudinally (axially) in the spaced apart region between aid first end plate and said second end plate,

7. An assembly as claimed in claim 6 wherein, said first end plate includes slots such that the end vertical terminals of each rod protrude beyond the plane of the end plate to allow further electrical connections.
8. An assembly as claimed in claim 6 wherein, said assembly includes a third end plate operatively below said second end plate which is mechanically coupled to said first end plate by means of tie rods disposed therebetween, thus ensuring pre-defined space and a robust assembly.
9. An assembly as claimed in claim 6 wherein, said top plate is a GFRP
plate
10. An assembly as claimed in claim 6 wherein, said bottom plate is a GFRP
plate