Impact of Rogowski sensors on the EMC performance of medium voltage power substations

The application of Rogowski sensors in protection and control equipment has many benefits compared to traditional instrument transformers. However, the signal levels of these sensors are small compared to possible disturbances, which raises questions regarding the immunity of such applications to switching transients. This contribution investigates a protection application with Rogowski sensors from the EMC point of view. Therefore, the disturbances that are generated by the primary parts of the switchgear are described. The propagation path of the interference is presented and differences to conventional applications are discussed. The effectiveness of different EMC measures is evaluated, based on the disturbance voltages occurring at the input terminals of the protection device.