Genova, Italy
Genova, Italy
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Zito P.,ENEA | Lampasi A.,ENEA | Baulaigue O.,French Atomic Energy Commission | Gharafi S.,French Atomic Energy Commission | And 8 more authors.
Fusion Engineering and Design | Year: 2017

The Crowbar System is a key protection system for the Super Conducting Magnet Power Supplies (SCMPSs) of JT-60SA, it is a Safety Relevant component and it is designed to be seismic resistant. The Crowbar System is operated in case of faults, quench of superconducting coils, plasma disruption or earthquake event, and it has to carry the current flowing through the superconducting coils in order to protect them and the SCMPS from over-voltages. The circuit configuration is based on a hybrid-making-switch, composed by a bidirectional-static-switch with a mechanical-switch and a varistor in parallel. The static-switch is composed by eight thyristors in bidirectional configuration (four connected in parallel and four in antiparallel), and it is designed to be able to safely intervene even if one thyristor or the mechanical-switch is not operating. The mechanical-switch (rated 50 kA making capacity) takes some tens of milliseconds to close, limiting the conduction time of thyristors. The overvoltage protection is performed by a voltage transducer, a Break-Over-Diode (BOD) and a varistor assuring a fast intervention with a high redundancy protection level. © 2017 Elsevier B.V.

Zito P.,ENEA | Lampasi A.,ENEA | Coletti A.,Fusion for Energy F4E | Novello L.,Fusion for Energy F4E | And 6 more authors.
Fusion Engineering and Design | Year: 2015

Fast Plasma Position Control Coils (FPPCC) PSs control the vertical position of the plasma during a plasma shot, to prevent Vertical Displacement Event (VDE), using FPPC coils installed in vacuum vessel for JT-60SA. For this task, the FPPCC PSs have to be very fast for reacting to plasma movements. Further, an open loop feed forward voltage control is adopted in order to achieve a fast control of FPPCC PSs. The main characteristics are: 4-quadrant AC/DC converter 12-pulse with circulating current, DC load voltage ±1000. V and DC load current ±5. kA.The overvoltage induced by FPPC coil during a plasma disruption can reach 10. kV and it is protected by a nonlinear resistor in parallel to the crowbar up to its intervention. All these technical characteristics have strongly influenced the design of the FPPCC converter and transformers which have been validated by simulation model of FPPCC PS. The outcomes of the simulation allowed to finalize the performances and dynamic behavior of voltage response. © 2015 Elsevier B.V.

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