FIELD OF INVENTION
The present invention generally relates to a method of manufacturing
superconducting coils. More particularly, the invention relates to a method
for manufacturing conducting coils adaptable in high temperature
superconducting transformers.
BACKGROUND OF INVENTION
In conventional high voltage transformer, copper or aluminum conductors
provided are sufficiently strong to remain in coiled from after making the
coils. Unlike HTSC tape, copper or aluminum conductor has better tensile
stress, strain, bending diameter. Accordingly, the interconnections are
achieved by regular soldering process along with the solid jumpers.
Prior to high temperature superconductors were disclosed in the art, Low
Temperature Super Conductors (LTSC) were used which required liquid
helium at 4.2 K for cooling superconducting motors/generators, and fault
current limiters. Such motors required that the LTSC coils be immersed in
liquid helium which is however expensive and difficult to handle. With
these inherent constraints, the LTSC could not find wider acceptance for
commercialization.
With the availability of High Temperature Super Conductors (HTSC) in the
art, many leading manufacturers of electrical equipments have shown a
renewed interest in the application of HTSC superconductors for
motors/generators, transformers, fault current limiters. The HSTC requires
liquid nitrogen for cooling, which is available aplenty and easy to handle as
compared to the liquid helium.
HTSC tape can carry 100 times more current than an equivalent sized
copper conductor. For an identical ampere-turns requirement, the size of
HTSC coils is much smaller than copper coils, requiring smaller window
size, and interalia an overall small size transformer.
With the present availability of HTSC tape, they can be exploited suitably
so as to be commercially viable for higher rating where high voltage is
invariably used for bulk transmission of power.
HTSC tape presently available in the art is bismuth based ceramic
superconductors. For making coils out of HTSC tape, a number of
restrictions has to be encountered for example. Tensile stress, wire
tension, minimum bending radius, maximum allowable temperature while
soldering. Being a delicate wire it does not have its own strength.
OBJECTS OF INVENTION
It is therefore an object of the invention to propose a method of
manufacturing and interconnecting conducting coils from superconducting
tape to form high temperature Superconducting transformers, which
eliminates the disadvantages of prior art.
Another object of the invention is to propose a method of manufacturing
and interconnecting conducting coils from superconducting tape to form
high temperature Superconducting transformers, which allows the
assembly of coils easy, and enables a near resistant free interconnection.
SUMMARY OF INVENTION
Accordingly, there is provided a method for manufacturing HTSC coils in
grooved spools having connectors for end terminals made of copper sheet.
HTSC wire while traveling on the surface of the spool is soldered at both
ends to the terminal connectors. HTSC wire does not take any bend while
ending. Terminal connector also has a groove over surface, where the tape
is soldered. This connector is fixed at the ends of the spool. These spools
are joined with copper inserts in between, the size and thickness of the
connector and those of the inserts are selected so that the current
densities are kept within limits.
GFRP hollow cylinders are used for holding the conductors. A continuous
groove is made on the outer periphery of the hollow cylinder called 'spool'.
Tape runs inside the groove. Two ends of the spool windings are soldered
to the end copper connectors. These copper connectors are fixed on the
spool ends. Thereby, each spool becomes one layer of winding. These
layers are connected with copper inserts, thickness of these inserts
constitutes the actual gap.
According to the invention, HTSC tape ends are terminated in the groove
of copper terminal and soldered without bending or sharp turns as the tape
has a restriction for minimum bend radius. Each grooved spool with the
winding and the end copper terminal operates as an Independent unit
thereby makes the assembly and intermediate testing easier. The cooper
terminals are disposed outside the spool allowing an easy connection of the
adjacent spools. A copper insert is adapted to connect the two end
terminals. Size and thickness of the copper insert, including profile of the
end terminals are selected to have an uniform and a low current density in
the current path. There is no degradation of performance of the
manufactured superconductors during operation. Electromagnetic forces
produced are taken care of by the grooved spools.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 shows round hollow GFRP spool having continuous grooves on the
outer surface according to the invention.
Figure 2 is a magnified view of the connector illustrating a connection
process of the adjacent coils.
DETAIL DESCRIPTION OF INVENTION
According to the invention, a plurality of concentric spools are assembled
to form HV and LV winding of a transformer depending upon the winding
design. Each spool have two end copper connectors fixed at the end of
spool. Adjacent spools have similar structure. End connectors of the
adjacent spools are disposed linearly for easy connection.
As shown in figure 1, a hollow GFRP spool (1) having continuous grooves
(5) is selected. A HTSC tape (6) is passed through the grooves (5) and the
tape (5) ends at a copper terminal connector (2) without taking any bend
or sharp curve. The copper terminal (2) also has a groove (4) matching
with the size of the HTSC tape (6) where the end of the tape (6) sits and is
then soldered with the end connector (2).
The terminal connector (2) is fixed with the spool (1) by means of a screw
arrangement (3). With this method, the HTSC coil (6) is secured in the
groove (5). Each spool (1) becomes an independent coil of a HTSC
transformer making it easy to assemble and to establish the
interconnection.
As shown in Figure 2, each adjacent spool (1) has copper connectors (2).
End connectors are joined rigidly with the help of a plurality of copper
spacers (5) and corresponding number of brass nuts and washers (6).
With this arrangement, it is easy to assemble the coils including its
interconnection with least resistance.
WE CLAIM :
1. A method of manufacturing and inferconnecting conducting coils
from superconducting tape to form high temperature
Superconducting transformers, the method comprising the steps of:
- providing at least one hollow GFRP Spool having a plurality of
continuous grooves;
- providing a terminal connector at the end of the at least one Spool,
the terminal connector having a groove matching that of the spool;
- joining the end terminal connector and the spool by fastening
means;
- causing a HTSC tape run through the grooves of the at least one
spool and securing the end of the tape in the groove of the terminal
end connector; and
- connecting the terminal connector in series with an adjacent
connector by means of copper spacers, nuts, and washer to form HV
and LV windings of high temperature superconducting transformer.
2. A method of manufacturing and inferconnecting conducting coils
from superconducting tape to form high temperature
Superconducting transformers as substantially described and
illustrated herein with reference to the accompanying drawings.

The invention relates to a method of manufacturing and interconnecting
conducting coils from superconducting tape to form high temperature
Superconducting transformers, the method comprising the steps of:
providing at least one hollow GFRP Spool having a plurality of continuous
grooves; providing a terminal connector at the end of the at least one
Spool, the terminal connector having a groove matching that of the spool;
joining the end terminal connector and the spool by fastening means;
causing a HTSC tape run through the grooves of the at least one spool and
securing the end of the tape in the groove of the terminal end connector;
and connecting the terminal connector in series with an adjacent connector
by means of copper spacers, nuts, and washer to form HV and LV windings
of high temperature superconducting transformer.