Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling

Several methods for electrical fault location have been developed and tested. As part of the electrical quality assurance program for the LHC, certain wires have to be subjected to a (high) DC voltage for the testing of the insulation. With the time difference of spark-induced electromagnetic signals measured with an oscilloscope, fault localization within ± 10 cm has been achieved. Another method used, and adapted for particular needs, is the synthetic pulse time-domain reflectometry (TDR) with a vector network analyzer (VNA). This instrument has also been applied as a low frequency sweep impedance analyzer in order to measure fractional capacitances of cable assemblies where TDR was not applicable.