Superconductivity is the ability to conduct electricity with no resistance. Heike Kammerlingh Onnes discovered superconductivity in 1911 when he found mercury had no resistance below 4.15K. Superconductors expel magnetic fields below their critical temperature, known as the Meissner effect. While promising technologies use superconductors, like maglev trains and MRI machines, widespread adoption is limited as most require cryogenic cooling below critical temperatures, with the highest at 138K. Research aims to develop room temperature "ultraconductors" for broader applications.

2. Definition
 Superconductivity is the ability to conduct electrical current
with no resistance , means no loss of energy.
 Which posses this property are called superconductors.

3. Discovery
• Superconductivity was first discovered in 1911 by the Dutch
physicist,Heike Kammerlingh Onnes.
• Onnes, felt that a cold wire's resistance would dissipate. This
suggested that there would be a steady decrease in electrical
resistance, allowing for better conduction of electricity.
• Onnes passed a current through a very pure mercury wire and
measured its resistance as he steadily lowered the temperature.
Much to his surprise there was no resistance at 4.15K(-2690C)

5. Animation of Cooper pairs

6. Meissner Effect
T > Tc
 Superconductors have negative susceptibility.
 If a superconductor is cooled below its critical temperature
while in a magnetic field, the magnetic field surrounds but
does not penetrate the superconductor. The magnet induces
current in the superconductor which creates a counter-
magnetic force that causes the two materials to repel.
T < Tc
h

7. h
h
Levitation of a magnet above a
cooled superconductor

8. Critical Temperature of some Superconductors
Material Critical Temp. (K)
Y 0.01(-2730C)
Al 1.20 (-2710C)
Hg 4.15(-2690C)
Pb 7.20(-265.950C)
V 4.3(-2680C)
Nb3Sn 18.00(-255.150C)
LaBaCuO 40.00(-233.150C)
YBCuO 92.00(-181.150C)
BiSr2Ca2Cu3Ox 113.00(116.150C)

9. Disadvantages of superconductors
Today’s commercialized superconductors require
cryogenic refrigeration in order to operate, severely
restricting their market adoption because of high capital
and operating costs.
The first of these is the restricted range for operating
temperature. Since the world record for the highest critical
temperature stands at 138 K(135.150C).
there is still a long way to go before superconductors are
available to the average user at room temperature.

10. ULTRA CONDUCTORS
 The materials exhibit a characteristic set of properties
including conductivity and current carrying capacity
equivalent superconductors, but without the need for
cryogenic support.
 some chemically distinct polymers have been used to
create Ultra conductors, including olefin, acrylate ,
urethane and silicone based plastics.
 very high electrical conductivity (> 1011 S/cm) and
current densities (> 5 x 108 A/cm2)
 over a wide temperature range (1.8 to 700 K).

11. NEW TECHNOLOGIES USING
SUPERCONDUCTORS:
Superconducting Fault Current Limiter(SFCL):
 When superconductor is cooled down to critical temperature
(about -186℃) or less, the resistance becomes zero.
 superconductor looses superconductivity and resistance occurs
rapidly (quench), when excessive current flows and exceeds
certain value (critical current). SFCL device uses this property.

12. SUPERCONDUCTING TRANSFORMER
 Superconducting windings are
cooled with liquid nitrogen.
 The superconducting wire can
flow 100 times more current
than copper wire of the same
unit area.
 superconducting transformer
is reduced more than 1/3 in
weight and volume, reduce
current loss more than 1/4
compared to the conventional
oil transformers.

13. SUPERCONDUCTING GENERATOR:
 HTS motors or generators are manufactured by using high-
temperature superconducting magnet.
 Neon re-condensing system, helium forced circulation system, the
refrigerator mount system and efficient and reliable cooling system
 Losses can be reduced down to 67% and efficiency can be increased
by 2%, compared to conventional motor.

14. SUPERCONDUCTING CABLE
 AC superconducting cable can carry power more than five times of
power and about 1/4 or less transmission loss compared to the
conventional cable of the same size
 and DC superconducting cable can have approximately 20 times more
transmission capacity and approximately 1/40 of the transmission loss
compared to the conventional cable of the same capacity .

15. SUPERCONDUCTING MAGNETIC
ENERGY STORAGE SYSTEM (SEMS):

16. Magnetically Levitated Trains (MagLev)
 As the train passes each coil, the motion of the
superconducting magnet on the train induces a current in these
coils, making them electromagnets. The electromagnets on the
train and outside produce forces that levitate the train and keep
it centered above the track.
 Trains are thrust forward by positively and negatively charged
magnets.
 The train floats on a cushion of air eliminating friction.

17. Application in Medical
MRI (Magnetic Resonance Imaging) scans produce detailed images of soft tissues.
 The superconducting magnet coils produce a large and
uniform magnetic field inside the patient's body.