The Academy of Sciences of the Czech rebublic - ASCR

Key components of Power Supply System of the new tokamak COMPASS-U delivered

Works on the Power Supply System of the new tokamak COMPASS-U successfully advance. Further key components of the System were delivered recently, which will enable to create extremely strong magnetic fields in the tokamak coils.


This includes mainly the high-power pulse transformers providing energy for the tokamak Toroidal and Poloidal Field coils. These special transformers, which are almost 4 metres high and weigh 21 tons each, had to be custom-made to fulfil specific requirements needed for powering of the tokamak: pulse operation and atypical frequency range 60 – 85 Hz. Two pairs of transformers have nominal pulse power 2x85 MVA and 2x53 MVA, respectively, and are capable of generating up to 7 seconds long pulses every 25 minutes.
Furthermore, the high-voltage switchgear with nominal voltage 6 kV dedicated for the Poloidal Field coils was delivered. The switchgear is equipped by special fuses containing small charges of explosives: the so-called pyrobreakers. These will enable to quickly and safely interrupt the high-voltage circuit to protect the flywheel generators with nominal power 108 MVA, which serve as the source of electrical energy for the tokamak.
For balancing of current in the tokamak Toroidal Field coils four choke coils were delivered. Each coil can operate with nominal current 50 kA, which is approximately 5000 times more than the current in an electric kettle.
Furthermore, the prototype of the Poloidal Field coils power converter was successfully tested. This power supply can regulate the current running through the tokamak coils in less than a thousandth of a second and thanks to this stabilize the position of the plasma in the tokamak. The prototype converter is based on the IGBT transistors and it fulfils a set of demanding parameters, which were required by the Institute of Plasma Physics. Completion of the prototype is one of the major milestones in the scope of the development and delivery of the Power Supply System.

Strategie AV21 Choke Coil

Strategie AV21 Prototype

Strategie AV21 Substation

Strategie AV21 Transformer












































Photo: IPP

26 Nov 2021