Mains power synchronous conducted noise measurement in the 2 to 150 kHz band

When testing large stationary equipment for EMC compliance, on-site testing is often the only option. In case of a fixed mains connection, use of an artificial mains network is problematic. Within In the framework of an European Research project on EMI testing of large installations, research has been performed on the performance of new and existing alternative methods. While researching existing solutions, several devices were found that served to monitor events on live mains connections. A lot of research is going on in the 2 to 150 kHz band as proper civil emission standards are lacking here and manufacturers apparently –deliberately– select the switching frequency of their power converters in this range in addition, most modern power input circuits are diode bridges followed by electrolytic capacitors, creating mains frequency synchronous interference. One of these methods involves using a high-pass filtered adapter using a commercially available common-mode coil as transformer to measure mains carried noise safely.