Conducted disturbances in industrial low voltage supply networks due to operation of high-power drive systems

Variable speed drives are usual and as well as systems in industrial installations nowadays. However, they generate significant conducted disturbances on the low voltage supply network leading to potential malfunction of other equipment which is connected to the supply. Extensive investigations were performed and published about disturbances in the harmonics frequency range as well as in the frequency range above 150 kHz in which limitations by relevant EMC standards are given. However, only little information is available for the frequency range in between, i.e. from 2 kHz to 150 kHz, in which nonetheless significant disturbances are generated. The paper presents results of measurements in this frequency range which were performed to obtain relevant information about disturbance levels in industrial supply networks. Inverter-fed drives with rated power of several hundreds of kW and detected disturbance levels are presented and assessed. Particular interest is taken for circuit breakers as components and potential victims in supply networks because they are directly exposed to those disturbances.