Sources of transient electromagnetic disturbance in medium voltage switchgear

Over the last decades, the worldwide market for medium voltage switchgear has shown a strong tendency to integrate power, control, protection and communication functions into a common panel. Today, this market demand is met by user-specific switchboards, consisting of modular composed switchgear panels with intelligent electronic devices (IEDs) for customized protection and control functionalities. Since switching operations inside a medium voltage switchgear are known to be serious sources of electromagnetic disturbance, the combination of the high voltage switching disturbance and strong coupling paths (due to the compact design) requires a carefully planning of electromagnetic compatibility. On the basis of practical measurements at a three panel switchgear installation, the paper will compare the interference behavior of different switching devices like air insulated disconnector, SF6 insulated disconnector and vacuum circuit breaker. The comparison will include the different disturbance levels of these sources in time and frequency domain and will also have a look on their most important propagation paths.