THE GROUND LOOPS DETECTION SYSTEM IN THE RFX MACHINE

RFX is a toroidal machine for the fusion research based on the RFP con figuration. During the pulse, in any conductive loop close to the mach ine very strong currents can be induced, which may damage the diagnost ics and the other instrumentation. To avoid loops, the earthing system of the machine is tree-shaped, however an accidental contact between metallic earthed masses of the machine may give rise to an unwanted lo op as well. An automatic system for the detection of ground loops in t he earthing system has therefore been developed, which works continuou sly during shutdown intervals and between pulses. In the paper the des ign of the detection system is presented, together with the experiment al results on prototypes.