Power Line Communication

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PLC in Mining Industry
The objective any mining company like TATA STEEL is to reduce the amount of energy used in mining through the increase in employee productivity and safety. Mining operations consist of several tasks. The highest efficiency can only be achieved with full coordination among the persons carrying out these tasks and if the locations of vehicles and people are known by those who coordinate the activities. In addition, the large number of risks of explosion has the potential to cause a major accident. Therefore, the establishment of a better communication system for the mine underground is very important and significant to modernize the mine management, increase the labour productivity, and strengthen the security to protect the lives and property of the mines. Present Scenario

At present, cable telephone communication, power line communication, sensor communication, telecommunication, leakage communication, and radio communication are the main forms of communication in a mine. Our study shows that, a variety of mobile communication methods have their limitary application under coal mine. Some mines still use hardwired wall-mounted telephones. The disadvantage of this technology is the obvious necessity that the user cannot be mobile. To reach this person, the caller must page the person who must then go to a wall-mounted telephone that may be a long distance away and in the case of an accident the telephone may be inaccessible to the injured person. Another popular technology , Leaky Feeder technology requires a relatively stiff,hard-to-install cable, about 5/8” in diameter, to be installed everywhere where communication is desired. To communicate the user must be in line-of-sight of the cable and not more than thirty or eighty feet away from the cable.

According to a survey conducted on how well current systems meet the needs for mining communication, 62 percent of Respondents replied negatively. None of them thought that mining communication needs were being met extremely well.

Some of their replies-
“Overall we cannot communicate well with miners.”
“There is the issue of battery, phone and wiring maintenance.” “Safety in an emergency is still an issue.”

As the power lines in an underground mine cover a broad area, if we can make full use of power lines to communicate, then we can completely solve the problem underground communication. The use of power lines saves the cost of additional cable and the labour cost for system installation. Furthermore, power lines are built and installed in a rugged manner. Any underground wire or cable, when fed an RF signal, tends to distribute that signal throughout its length. Carrier current systems utilize this fact to establish communication paths using existing mine wiring. Carrier current devices are basically FM radio transceivers that transmit and receive over existing mine wiring instead of using an antenna system. The LF (low-frequency) and MF (medium frequency)KP ranges propagate best in carrier current systems. A common example of a carrier current system is the trolley carrier phone systems presently used in many mines. Another example is the shaft communication systems that utilize the hoist rope itself to establish communications to and from the cage. The most modern system, based on MF, promises to be the most effective of a l l .

But there are lots of complex interference noises in power line communication under mine. More recently, the maturity of wireless as an accepted medium has increased the demand for instant, reliable, portable communication. Underground mines, however, have proved resistant to wireless communication due to environmental conditions that limit the transmission of radio waves. “Mines are looking to find such a system. It would become universal over time due...
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