Location of partial discharge occurring in propulsion coil of superconducting Maglev system using radio interferometer system with EM shield

Superconducting magnetic levitation (Maglev) system needs a large number of ground coils: propulsion coils and levitation-guidance coils that are attached to both the concrete sidewalls of the guideway, which corresponds to the rails of a conventional railway. The propulsion coils are energized in order to propel the Maglev vehicle by a three-phase alternating current from a substation, which generates a shifting magnetic field on the guideway. The propulsion coils are made of aluminum conductors insulated with epoxy resin. Condition monitoring and diagnosis for insulating materials of ground coils are required in order to operate the Maglev system safely. We have previously shown that the radio interferometer system can locate a partial discharge (PD) occurring in the propulsion coil under noise environment through outdoor experiments. In this study we added EM shields to the radio interferometer system in order to suppress radio noise from the rear and both sides of antenna-array and reduce the reflection of EM waves. It was easier to obtain the EM waves emitted from PD because the radio noise could be suppressed. We also investigated the effects of a mock-up body (part of the sidewall) of Maglev vehicle on locating PD occurring in the propulsion coil.