Influence of Temperature on Generator Current and Magnetic Field of a Proximity Detection System

  • Jingcheng LiEmail author
  • Adam Smith
  • Jacob Carr
  • Bruce Whisner


Electromagnetic-based proximity detection systems (PDSs) are utilized on mining machinery to protect workers from being pinned or struck. These systems generate magnetic fields covering the space around a machine, and a miner-wearable component (MWC) detects the field. The PDS determines the distance of miners relative to the machine based on the detected magnetic flux density in the magnetic field. This information is used to establish warning and shutdown zones around the machine. Maintaining a stable magnetic field is essential for system accuracy. However, components used to generate magnetic fields can be influenced by temperature changes. Depending on ventilation conditions and seasonal alternation, a PDS can be subject to significant temperature fluctuation. To better understand and quantify this phenomenon, researchers from the National Institute for Occupational Safety and Health (NIOSH) developed an experimental apparatus to study the influence of temperature on magnetic field generator circuits used in PDSs. Results from the study show that the electric current through a generator can be influenced by both ambient and internal temperatures, modifying the magnetic field that is produced. These findings show that temperature can significantly influence the ability of PDSs, used in underground coal mines, to accurately determine a worker’s position in relation to mining machine.


Magnetic field Magnetic distribution model Proximity detection system Temperature 



The authors sincerely thank Mr. Jeffrey A. Yonkey and Mr. Joseph DuCarme for their support in designing and conducting this study.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that there is no conflict of interest.


The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.


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Copyright information

© This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection 2019

Authors and Affiliations

  • Jingcheng Li
    • 1
    Email author
  • Adam Smith
    • 1
  • Jacob Carr
    • 1
  • Bruce Whisner
    • 1
  1. 1.Pittsburgh Mining Research DivisionNational Institute for Occupational Safety and HealthPittsburghUSA

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