Magnetic field immunity of the low voltage current breakers installed inside the ITER tokamak building

Two typologies of circuit breakers for low voltage distribution system have been extensively tested immersed in a static magnetic field, an environmental condition similar to what is expected inside the ITER tokamak building. Functionality tests with and without load, protection relay tests and life tests at nominal ratings have been performed. The results allowed to point out a magnetic field limit for regular operation irrespective of the installation, to find the operability limits for higher magnetic field and to assess if magnetic field changes the wearing during the life.