The electrical circuit of the HERA (Hadron Electron Ring Accelerator) proton ring (p-ring) is divided in octants so that in the case of a quench, the current has to be commutated to dumping resistors. The authors describe the application of superconducting switches which would enable the main circuit to remain at 4 K during a quench while the current is forced to flow through instantaneously loaded leads and dumping resistors. The main specifications of the required switches are: current of 6.5 kA, minimum off-resistance 12 Omega , energy absorbed 1 MJ, and self protecting. The various design and feasibility aspects of superconducting switches for this application are discussed. The requirement of being passively protected against a self-quench is considered the most critical design problem. It is still uncertain whether it remains necessary to apply an active protection scheme to enable safe operation of the switch.
ten Kate, H. H. J., Wipf, S. L., ten Haken, B., & van de Klundert, L. J. M. (1988). Development of a superconducting protection switch for the HERA P-ring: design study and demonstration models. IEEE transactions on magnetics, 24(2), 1178-1181. https://doi.org/10.1109/20.11443