The Mine and Safety Health Administration (MSHA) recently completed tests and provided approval for Zero Ground’s High Frequency Extraction System (HFES). The system addresses existing safety concerns and unplanned downtime associated with high frequency ground currents generated by variable frequency drives (VFDs). These damaging currents can adversely affect the operation and accuracy of sensitive electronic and communications equipment, including environmental sensors used in mine-wide monitoring systems. Although VFD-generated currents cannot be eliminated, the HFES reduces them to safe levels by directing them away from hazardous locations and sensitive equipment.

The HFES cable assembly meets the MSHA requirement for electric cable flame resistance as New Technology under 30 CFR, Part 7, Subpart K and as a flame resistant solid product. MSHA on-site testing verified that the HFES reduced VFD-generated currents to levels that are safe and meet MSHA regulations, policies and procedures. Excerpts from this MSHA investigative report can be viewed at: