Using absorbing filters (such as common mode chokes or nanotech filters) in combination with a shaft grounding ring provides a robust defense against VFD-induced shaft currents.  These solutions work synergistically: the filter absorbs high-frequency common-mode currents at the source (VFD output), while the shaft grounding ring safely diverts any residual shaft voltage to ground, bypassing the bearings entirely.  This dual approach is especially effective in preventing EDM fluting, pitting, and premature bearing failure.