This document summarizes a seminar presentation on using superconductors for surge current protection. It introduces surge currents and the need for protection against them. It then discusses superconductors and how they can conduct electricity with zero resistance below a critical temperature. Different types of superconductors are presented, as well as how superconductive surge current limiters work by providing high impedance above a given current threshold. The document concludes by discussing advantages of using superconductors for this application and future plans to introduce them into power grid transmission systems.

1. SEMINAR ON
SURGE CURRENT PROTECTION USING
SUPERCONDUCTORS
Department of Electrical Engineering
Submitted to :-
Mr. Manish Trikha
Guided by :-
Mr. Saurabh Saxena
Submitted by :-
Chirag Agrawal
(1208221014)
Branch - EN

2. CONTENT
 INTRODUCTION
 WHAT IS SURGE CURRENT
 NEED OF SURGE CURRENT PROTECTION
 WHAT IS SUPERCONDUCTOR
 MEISSNER EFFECT
 TYPES OF SUPERCONDUCTOR
 SURGE CURRENT LIMITER
 OTHER METHODS FOR SURGE CURRENT PROTECTION
 ADVANTAGES
 FUTURE PLANS
 CONCLUSION

3. INTRODUCTION
 Modern power system are growing fast with more
generators, transformers and large network in the
system. Whenever a fault occurs there is a need for
the protection of these system.
 Here we’ll discuss the use of superconductor as
protective device for surge current protection.
Superconductors conduct electricity, offering zero
resistance below certain temperature. We study
different types of superconductor as surge current
limiter and their working.

4. WHAT IS SURGE CURRENT?
 The maximum instantaneous input current drawn by
an electrical device when first it is turned ON , is
defined as surge current.
 It is also known as inrush current or input surge
current or switch on surge.
 Inrush current can be as high as 100 times the
normal steady state current .

5. Surge current waveform

6. NEED OF SURGE CURRENT PROTECTION
 High inrush current can affect the electrical systems
by tripping fuses and circuit breakers unnecessarily.
 If inrush protection is not in place, relays and circuit
breakers must be rated higher than any possible
inrush current.
 Inrush Current can also cause pitted contacts on
switches and relays due to arcing of the contacts.
 This surge current can cause component damage
and/or failure within the equipment itself, blown
fuses, tripped circuit breakers .

7. WHAT IS SUPERCONDUCTOR ?
 Metallic elements, alloys or compounds that will conduct electricity
without resistance below a certain temperature, is called a
Superconductor.
 The dutch physicist ‘HEIKE KAMERLINGH ONNES’ of leiden
university was the first person to observe superconductivity in
mercury.
 Superconductivity is a phenomenon of exactly zero electrical
resistance that apply in certain materials when cooled below critical
temperature.
 Superconductors are extraordinary because they take no energy to
make current flow .So no energy is lost to friction to sustain the
current.

8. MEISSNER EFFECT
 The phenomenon of exclusion of magnetic flux or ejection of
lines of magnetic induction from the interior of bulk
superconductors, when they are cooled below the transition
temperature is called Meissner’s effect.

9.  Superconductors have electronic and magnetic
properties. That is, they have a negative
susceptibility, and acquire a polarization OPPOSITE
to an applied magnetic field. This is the reason that
superconducting materials and magnets repel one
another.
 If the temperature increases the sample will lose
its superconductivity and the magnet cannot float
on the superconductor.

10. Magnet levitating on a Superconductor .

11. TYPES OF SUPERCONDUCTOR
• Low temperature superconductor :- Those
whose critical temperature is below 77 k.
Example :- lead and mercury (common LTS),
Ti, V, Zr, Nb etc.
• High temperature superconductor :- Those
whose critical temperature is above 77 k.
Example :- YBCO, BSCCO etc.

12. SURGE CURRENT LIMITER
 A surge current limiter is a device which limit
prospective surge current when a instant high
current occurs at starting . Generally SCL are
superconductor SCL.

13. How does it works ?
Superconductor SPD or SCL prevents the
current from exceeding a given value.
It presents a negligible impedance for normal
current value.
It naturally and automatically inserts a high
impedance above a given current.
Superconductor SPD’s impedance disappears
automatically after the surge clearance and a
certain delay.

14. Process for protection from surge current

15. SUPERCONDUCTIVE SCL

16. (i) If current flow normally then ;
(ii) If surge current flows then ;

17. Inductive type SSCL

18. Cryostat - It creates the low temperatures for
superconductivity hold up.
The inductive type SSCLs works like
transformer with shorted superconducting
secondary winding. In normal operation the
primary winding resistance and leakage
inductance determine the impedance of the
limiter. If the surge occurs, the resistance of
the secondary winding is the superconductor
quenches. The value Rsc is transferred into the
primary side by the K2=(w1/w2)2 and the SCL
impedance increases.

19. Superconductors providing a variable resistance

20. Superconductor as a variable resistor
Superconductors are strongly dependent on
direction of an applied external magnetic
field. The resistance of a superconductor can
change by several orders of magnitude by
applying a magnetic field.
Thus a superconductor varies it’s resistance in
the circuit.

21. WHY WE USE SUPERCONDUCTORS ?
The losses are reduced by using
superconductors.
The best conductivity is provided by
using superconductors.
These are the ideal conductors.

22. OTHER METHODS FOR SURGE
CURRENT PROTECTION
Are following :-
Resistors,
Thyristors,
Triacs,
Inductors,
NTC thermistor,

23. ADVANTAGES
Safety, reliability, and power quality.
Cost for C.B. and fuses can be reduced.
Life of transformers extended.
Reduced or eliminate wide area, blackouts.
Provide protection to T&D equipment.

24. FUTURE PLAN
TEPCO will develop a three-phase limiter over
the next three to four years and test it in the
grid within this century. The current plan is to
introduce solid state breakers for distribution
before installing superconductive FCL.
The true application for the superconducting
FCL is at transmission voltages of 500 kV.

25. CONCLUSION
 The purpose of this presentation was the study of
surge current protection using superconductors. The
Superconductor Fault Current Limiters offers efficient
advantages to power systems and opens up a major
application for superconducting materials.

26. REFERENCES
http://www.scribd.com/doc/115890153/surge-
current-protection-using-superconductors
http://jntuhome.com/surge-current-protection-
using-superconductors-seminardownload-full-
paper-eee-seminar-topics/
http://kguru.info/t-surge-current-protection-
using-superconductors-ppt--55999
http://en.wikipedia.org/wiki/Surge_protector
www.ecoflow.org/index.php?option=com_conten
t&id=51&ltemid=55

27. ANY QUERIES??