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Surge current protection using superconductor.

Surge current protection using superconductor. Fault Current. The short ckt current can exceed by a factor of 100 of the nominal current. Produce mechanical and thermal stress proportional to square of the current. Fault current limiter is used to limit this current, it must possess:

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Surge current protection using superconductor.

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  1. Surge current protection using superconductor.

  2. Fault Current • The short ckt current can exceed by a factor of 100 of the nominal current. • Produce mechanical and thermal stress proportional to square of the current. • Fault current limiter is used to limit this current, it must possess: • Zero impedance(at normal operation • High Impedance(at faults) • Provide detection and recovery of the fault instaneously(16ms)

  3. Superconductor fault current limiter • Superconductor used because of their sharp transition from zero resistance at normal currents to finite resistance at higher current densities(above critical temp) • Type of Superconductor:Low Temperature(c<=23k),High Temp(c<=70) C=critical temp

  4. Types of Superconductor • Low Temp:Low AC losses. very high current carrying capacity, hotspots formation.. • High Temp:poor heat conductor, no hot spots.Examples:BSCCO,YBCO compounds. • SFCL types includes Resistive SFCL,Inductive SFCL.

  5. Resistive SFCL • Superconductor connected in series with the line to be protected. • To keep it superconducting, it is usually immersed in a coolant that is chilled by a refrigerator. • In case of a fault the inrush of current and magnetic field take the super conductor into the transition region, thereby the increasing resistance limits the fault current. • The behavior of resistic fault current limiter is largely determined by the length of the superconductor and the type of material used for it.

  6. SUPERCONDUCTORS AS VARIABLE RESISTORS • 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.

  7. Shielded Core SFCL • The shielded core fault current limiter basically a shorted transformer • The device’s primary coil is normal conducting and connected in series to the line to be protected, while the secondary side is superconducting and shorted

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