Chapter 6B: Warm powering of the superconducting circuits

The warm powering of the HL-LHC involves the new circuits of the Inner Triplets and the Separation/Recombination magnets in Point 1 and Point 5, the powering of the 11 T magnets in Point 7, and the final R2E consolidation phase in LS3. The LHC was built with modular power converters to facilitate maintenance and integrate the redundancy principle. Redundancy was foreseen in power converters rated above 600 A. This has proven to be a real asset during operation. The n + 1 redundancy indeed allows the converter to be operated even with one module in fault. The advantages are: (i) in case of fault, only one sub- converter is not operational and usually this does not generate a beam dump; (ii) the LHC can run with some faulty sub-converters and all interventions for repairing can be performed during a technical stop of the machine. With the exception of dipole circuits (whose power converters are based on thyristors technology), switch-mode technology was chosen for the LHC power converters in order to minimize their size and assure low output voltage ripple. All LHC power converters rated at currents above 120 A are water-cooled, inducing a size reduction of the hardware. All these design principles will be maintained for the new HL-LHC power converters and the use of switch-mode technology extended to all new designs.