Mining Contract: Application of Extreme Power Line Communication Methods to Mine Environments

Contract Status & Impact

This contract is complete. To receive a copy of the final report, send a request to mining@cdc.gov.

Electrical power cables are typically the most robust conductors found in underground mines; therefore, the use of power line carrier (PLC) techniques can potentially enhance a communication system’s ability to survive an adverse event such as a mine explosion or fire. PLC communication systems use electrical power distribution cables for voice and data transmission, and this contract assessed the suitability of this approach for underground coal mine power systems. Because power cables are part of the existing mine infrastructure, their use should result in cost savings for equipment and installation when compared to non-PLC communication systems. However, potential problems include frequency (bandwidth) limitations, power system noise, and high voltage safety issues.

This contract confirmed the technical feasibility of employing PLC techniques for voice and data communication over underground mine electrical power systems by designing and constructing an experimental PLC communication system and conducting in-mine tests. The system tested differs somewhat from PLC systems in non-mining applications, in that signals are carried on mine power system grounding conductors rather than individual power line phase conductors. This modification was due to safety concerns related to coupling onto high voltage conductors.

The research performed under this contract ultimately achieved reliable communication at 6 kb/s data rates over 5,000 ft of energized 12.4 kV mine power distribution cable at spread-spectrum center frequencies of 0.75 to 4 MHz, but had limited success over 10,000 ft of cable using an 8-kb/s data rate and 2-MHz center frequency.

Despite the system survivability and infrastructure cost advantages of PLC communication, the private sector is unlikely to commercialize this technology because there is not currently sufficient regulatory or market pressure to do so. The research under this contract, however, did establish PLC as a technically viable option for future systems targeting lower-cost primary (normal operation) communication systems for small mines, and high-survivability emergency systems for larger mines.