1. ABSTRACT
In recent years, superconducting fault current limiter
(SFCL) has become one of the forefront topics of currentlimiting technology in the world.
The implementation of FCL devices may also
provide the opportunity to increase distribution and
transmission
equipment
reinforcement requirements.
utilization
and
reduce
2. INTRODUCTION
Almost in every field of modern civilization there is
the requirement of electrical energy which has
resulted in a considerable increase of electrical power
consumption.
Fault-current limiters using high temperature
superconductors offer a solution to controlling faultcurrent levels on utility distribution and transmission
networks.
Development of superconducting fault-current limiters is
being pursued by several utilities and electrical
manufacturers around the world, and commercial
equipment is expected to be available by the turn of the
century.
3. THE MAXIMUM FAULT CURRENT IN
A SYSTEM VARIETY OF REASONS
• Electric power demand increases (load growth) and
subsequent increase in generation.
• Parallel conducting paths are added to accommodate
load growth.
• Interconnections within the grid increase.
• Sources of distributed generation are added to an
already complex system.
4. SUPERCONDUCTOR FAULT CURRENT
LIMITER (SFCL)
•SFCL is a new power device to automatically limit a
fault current to a safe level with the superconducting
property.
•When superconductor is cooled down to critical
temperature (about -186℃) or less, the resistance
becomes zero. However, superconductor looses
• superconductivity and resistance occurs rapidly
(quench), when excessive current flows and exceeds
certain value (critical current). SFCL device uses this
property.
•A superconductor is a material that can conduct
electricity or transport electrons from one atom to another
with no resistance
5. SUPERCONDUCTOR CHARACTERISTICS
•Zero DC resistance
•High current density (high power)
•High electro‐magnetic shielding (low EMF)
These characteristics require:
•Cooling below a critical temperature
•Current levels below a critical current
•Magnetic field below a certain magnitude
8. 1. THE INDUCTIVE SFCL
Fig.. Inductive fault-current limiter
The inductive limiter can be modeled as a
transformer. The impedance of this limiter in
the steady state is nearly zero, since the zero
impedance of the secondary winding is
reflected to the primary.
9. 2. THE RESISTIVE SFCL
Fig. Resistive fault-current limiter
Resistive SFCLs utilize the superconducting
material as the main current carrying conductor
under normal grid operation.
10. 3. THE SHIELDED-CORE SFCL
Fig. Shielded-Core fault-current limiter
shielded-core designs have worked well, their size
and weight have limited grid
11. 4. THE SATURABLE-CORE SFCL
Fig. Saturable-Core fault-current limiter
This concept utilizes two iron cores and two AC windings
for each phase. The AC windings are made of conventional
conductors that are wrapped around the core to form an
inductance in series with the AC line
12. DESIGN PARAMETERS OF SFCLS
•System voltage
•Continuous current rating
•Maximum 3phase short circuit current or source impeda-
nce
•Fault clearing time; backup clearing time, reclose sequence (if any)
•1st cycle peak fault current desired to be limited
•Per unit level of rated current for FCL transition
13. SUPERCONDUCTOR FAULT CURRENT
LIMITER APPLICATIONS
1. Fault Current Limiter In The Main Position
2. Fault Current Limiter In The Feeder Position
3.Fault-Current Limiter In The Bus-Tie Position
14. 1. FAULT CURRENT LIMITER IN THE
MAIN POSITION
Fig. Fault-current limiter in the main position
The fault current limiter protects an individual circuit on
the bus. Underrated equipment can be selectively
protected as needed in this manner an fcl can also be used
to protect the individual loads on the bus.
15. 2. Fault Current Limiter In The Feeder
Position
fig. Fault Current Limiter In The Feeder Position
FCL can also be used to protect individual loads on
the bus . The selective application of small and less
expensive limiters can be used to protect old or
overstressed equipment that is difficult to replace, such
as underground cables or transformers in faults.
16. 3.Fault-Current Limiter In The Bus-Tie
Position
Fig. Fault-current limiter in the bus-tie position
•Separate buses can be tied together without a large
increase in the fault duty on either bus.
•During a fault, a large voltage drop across the
limiter maintains voltage level on the unfaulted bus.
17. ADVANTAGES OF
SUPERCONDUCTOR FAULT
CURRENT LIMITER
•Because the resistance of superconductive material is
so low, there is no current wastage when they are used
to conduct electricity.
• When used in the process of magnetic levitation, no
kinetic energy is wasted due to friction from contact
with the ground.
18. DISADVANTAGES OF
SUPERCONDUCTOR FAULT
CURRENT LIMITER
•To show their properties, and be of any use, they
must be at critical temperature, which can be costly.
• They emit strong magnetic fields which can affect
humans by causing blindness, sterility, brain cancer
and other things.
19. CONCLUSION
With increase in generation, comes an increase in shortcircuit current in a transmission line during faults.
Utilities usually predict how much fault current exists in
the line and can forecast its increase over a period of
time.
The result is a lower cost system that is smaller and
has much lower losses.
