System reduces VFD ground currents

Company says its solution, which meets NEC 250 grounding requirements, was engineered for use wherever ac induction motors are operating in conjunction with variable frequency drives and for other applications where large switching power supplies are used.
By Control Engineering Staff May 28, 2008

Waukegan, IL Zero Ground announced that its high frequency extraction system (HFES) has been formally approved by the U.S. Dept. of Labor, Mining and Safety Health Administration (MSHA) for use in underground and surface mines located in the United States, approved by the Bureau of Mine Safety, Commonwealth of Pennsylvania, and issued a “P” number to be used in conjunction with the MSHA approval number. Past

testing by MSHA


The company says its solution, which meets NEC 250 grounding requirements, was engineered for use wherever
Approved under the MSHA classification as “New Technology,” the patented cable assembly and installation method addresses existing safety concerns and unplanned downtime in mining applications associated with high frequency ground currents, the company says.
The company points out that in all VFD and motor applications, and those used specifically in the mining industry, the presence of high frequency ground currents can cause sparks, arcing and electrical shocks. High frequency ground currents have been known to affect sensitive electronic equipment, such as environmental sensors used in mine-wide monitoring systems (MWMS). These systems may be compromised as a result of high frequency ground currents, causing safety concerns and eventual system malfunction.
— Edited by C.G. Masi , senior editor
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