Selective partial discharge measurements on assembled outer-cone cable plugs for on-site routine tests of rail vehicles

Medium voltage cables with assembled outer-cone type plugs (also called T-plugs) are widely applied in 15 kV- and 25 kV-supplied railway rolling stock. They connect the roof-mounted switchgear with the inside- or underfloor-mounted traction transformer. Poorly assembled or badly connected plugs are not reliably detected during routine voltage withstand tests on train level. In recent years this fact has led to several incidents on rail vehicles due to electric breakdown of plugs. These incidents affected the nearby equipment negatively without yet a safety impact on persons. After-installation partial discharge (PD) tests on train level can reveal poor assembly and plugging. A major problem of on-site PD measurements on assembled and connected plugs is the high environmental noise and PD…