Protection of individuals in nets with frequency inverters The flexible controlling of modern asynchronous induction motors by using frequency inverters is the state of technological development today. For adherence to relevant EMC - guidelines some measures are necessary. For example the use of shielded lines and EMC - filters. Through these measures a unwanted leakage current is floating to ground. These leakage current could be large enough to release a conventional Residual Current-operated circuit breaker (RCCB) for the protection of individuals. For this reason the protection of individuals by resorting a RCCB is disclaiming when using a frequency inverter. To close this gap is the objective of the EFRE - project "protection of individuals in nets with frequency inverters". For the implementation of this goal the leakage current has to be measured exemplarily. These measurements take place in time and frequency range. Therewith a declaration about the course, the root mean square (RMS) and the single frequency components is possible. These measurements are accomplished under variation of different parameters like chopper frequency, cable length and the speed of rotation of the drive. As result of these measurements stands an extensive data collection to the behaviour of the leakage current at the different operating cases of the frequency inverter. A RCCB with a frequency response coordinated with the typical leakage current of the frequency inverter was developed. This RCCB accomplish VDE 0664-100 (RCCBs type B) for the protection of individuals. In addition to these measurements we are working on the development of EMC - filters with lower leakage current. These ensure optimal protection of individuals in connection with the RCCB (type B), developed in this EFRE - project, with simultaneous working reliability. More information about this project on the homepage of the project (only german).

Protection of individuals in nets with frequency inverters

The flexible controlling of modern asynchronous induction motors by using frequency inverters is the state of technological development today. For adherence to relevant EMC - guidelines some measures are necessary. For example the use of shielded lines and EMC - filters. Through these measures a unwanted leakage current is floating to ground. These leakage current could be large enough to release a conventional Residual Current-operated circuit breaker (RCCB) for the protection of individuals. For this reason the protection of individuals by resorting a RCCB is disclaiming when using a frequency inverter. To close this gap is the objective of the EFRE - project "protection of individuals in nets with frequency inverters". For the implementation of this goal the leakage current has to be measured exemplarily. These measurements take place in time and frequency range. Therewith a declaration about the course, the root mean square (RMS) and the single frequency components is possible. These measurements are accomplished under variation of different parameters like chopper frequency, cable length and the speed of rotation of the drive. As result of these measurements stands an extensive data collection to the behaviour of the leakage current at the different operating cases of the frequency inverter. A RCCB with a frequency response coordinated with the typical leakage current of the frequency inverter was developed. This RCCB accomplish VDE 0664-100 (RCCBs type B) for the protection of individuals. In addition to these measurements we are working on the development of EMC - filters with lower leakage current. These ensure optimal protection of individuals in connection with the RCCB (type B), developed in this EFRE - project, with simultaneous working reliability.

More information about this project on the homepage of the project (only german).

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