Reengineered EMC Filters Minimize Earth Leakage Currents

March 27, 2019 by Paul Shepard

TDK Corporation has reengineered and improved the EPCOS LeaXield™ active leakage current filter, a unique solution that is able to minimize earth leakage currents in converter-based drive systems. LeaXield is designed for applications in variable-speed drives such as those in machine tools, pumps, compressors, conveyance systems, and other pluggable devices.

In these systems aggregate earth leakage currents can cause RCDs (residual current devices) to trip at their threshold. As a result, RCDs are either not usable or only with substantial additional outlay.

LeaXield is available for load currents of up to 50A at a rated frequency of 50/60 Hz and phase-to-phase voltages of up to 520Vac. The active leakage current filter is connected between the RCD and the EMC input filter of the converter in industry-standard three-phase TN power grids and does not require an additional power supply. LeaXield can be utilized for earth leakage currents of up to 1A and can effectively compensate leakage currents over a wide spectral range from 150Hz to approximately 30kHz.

LeaXield couples a 180° phase-shifted current with identical amplitude to the leakage current to the respective phases and feeds it back to the source. This prevents the leakage currents from flowing through the RCD and tripping it unintentionally, thus increasing plant availability.

Thanks to its compact design, the LeaXield is also well-suited for retrofitting existing installations. As no external power supply is required and installation outlay is minimal.

Main applications

  • Converter-based variable-speed drives
  • Pluggable devices

Main features and benefits

  • Minimization of earth leakage currents up to 1A
  • High leakage current compensation in the frequency range of 150Hz to approximately 30kHz
  • Compact design
  • Minimal installation outlay, no external power supply required
  • Increased plant availability