LeaXield filter for minimizing ground leakage current

     TDK Group has released the EPCOS LeaXield active filter module, which provides a new solution to minimize leakage current in inverter systems. Too high a leakage current can cause the RCD(residual current detection device) to trigger, which means that a low threshold RCD(such as 30 mA) cannot be used in some applications, or requires an expensive additional cost. The LeaXield active filter module can be connected between the RCD(residual current device) and the EMC input filter of the inverter in a standard three-phase industrial grid, without the need for additional power sources.

     LeaXield detects the common-mode current on the load side through a current mutual inductance transformer. The power amplifier generates a feedback current that is in the opposite phase of the leakage current and is then fed into the power line through a capacitor, which almost completely cancels out the leakage current. LeaXield is designed for 3-phase grid applications with frequency 50/60Hz, rated voltage of 520 V AC, and rated current of up to 150 A. Currently, the new active power filter can be used in systems with leakage currents up to 1000 mA.

     In addition to minimizing leakage current, the LeaXield active filter module enhances the EMC performance of the drive system at frequencies up to approximately 500 kHz; When the frequency is 4 kHz, the new active filter module can obtain a typical common-mode attenuation value of up to 30 dB. When the frequency is 10 kHz, the attenuation value is 40 dB; At a frequency of 150 kHz, this attenuation value is 15 dB.

     In order to improve the EMC and RCD compatibility of the drive system, the EPCOS LeaXield module can be easily installed in the existing frequency conversion system. In addition, LeaXield can be integrated into new EMC filter solutions to reduce the use of expensive common mode inductors.