TDK Corporation has reengineered and improved the EPCOS LeaXield active leakage current filter, described as a unique solution that is able to minimize earth leakage currents in converter-based drive systems. The system 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 residual current devices (RCDs) 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 520 Vac. 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 spectral range from 150 Hz to approximately 30 kHz.
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.