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Similar approach was followed for the DR design safe manner; the most important protections have
of PFC QPC, except for the aspect related to the a back-up detection system, i.e. a secondary pro-
maximum resistor temperature which was limited tection chain relying on different transducers.
to 200 ºC because these resistors will be installed All QPC components are supplied via uninterrup-
in indoor halls, where also other power equipment table power supply so as the correct functioning is
are installed (figure 5). assured even in case of full or partial loss of mains
The TFC DR is rated for 350 MJ; it is divided in two voltage.
identical parts with the common point connected
to the earth through a grounding resistor, thus Conclusions
allowing halving the voltage to ground seen from
each TFC terminal; the PFC DRs are rated for 70 This paper describes the Quench Protection Cir-
MJ, 100 MJ, 200 MJ, depending on the coil which cuits (QPC) for the superconducting magnets of
they are connected to. the JT-60SA Satellite Tokamak under construction
in Naka Fusion Institute of Japan Atomic Energy
The Control and Protection Agency . An innovative design solution composed
System of a mechanical-static Hybrid Circuit Breaker (CB)
was developed (figure 6). The mechanical ByPass
Each TFC and PFC QPC unit includes a dedicated Switch conducts the continuous current while the
Control and Protection System installed in a Local static Circuit Breaker is provided in parallel for cur-
Control Cubicle (LCC) which allows both the “Re- rent interruption; a pyrobreaker assures back-up
mote Control” and “Local Control” of the QPC unit. protection. The main choices of the final design
In “Remote Control”, QPCs receive hardwired acti- and the description of main equipment have been
vation commands and their operation is monitored described.
by the JT60SA Supervisory Control System and The whole project, from the detailed design to the
Data Acquisition System (SCSDAS). The “Local installation and commissioning on site, was carried
Control” is just intended for the purpose of testing, out by Nidec ASI in strict cooperation with Consor-
trouble-shooting and commissioning; in these ca- zio RFX and also Fusion for Energy (F4E) and Ja-
ses each QPC is operated from a Human / Ma- pan Atomic Energy Agency (JAEA) with the target
chine Interface (HMI).The communication with the to achieve the highest system flexibility, reliability
SCSDAS was realized via Reflective Memory. and safety. The complexity of the whole system,
The hardware control structure for each QPC is in which many devices had to be integrated for a
based on ARTICS Industrial Automation Suite, coordinated operation, has also required a special
Nidec ASI customizable industrial hardware and effort in the design. A careful analysis of the fault
software platform. This architecture is capable to conditions and the relevant protecting actions has
integrate different tasks and in particular both the been carried out. Nidec ASI experience in the field
Slow Control and Monitoring of the QPC compo- of power electronics and the joint studies brought
nents and the Fast Control to collect QPC activa- to the best possible solution using the most advan-
tion commands and to coordinate the intervention ced available technology.
sequence of QPC in normal operation and in case All the 13 QPC units were installed in 2014 and
of pyrobreaker intervention. commissioned early in 2015; after the completion
All protection circuits were implemented in a fail- of commissioning activities, the final acceptance
tests were successfully performed in June 2015,
allowing the closure of the QPC procurement ac-
tivities on 31 July 2015, according to the original
schedule.
Fig. 5 - Discharge Resistor References
60 Impiantistica Italiana - Settembre-Ottobre 2015
[1] Novello L., Gaio E., Piovan R.: Feasibility Stu-
dies of a Hybrid Mechanical-Static DC Circuit Bre-
aker for Superconducting Magnet Protection - IEEE
Transactions on Applied Superconductivity, 19(2),
pp. 76-83, 2009
[2] Gaio E., Novello L., Piovan R., Shimada K., Te-
rakado T., Kurihara K., Matsukawa M.: Conceptual
Design of the Quench Protection Circuits for the JT-
60SA Superconducting Magnets - Fusion Enginee-
ring and Design, 84 (2-6), pp. 804-809, (2009)
[3] Novello L., Baldo F., Ferro A., Maistrello A., Gaio
E.: Development and Testing of a 10-kA Hybrid Me-
