Data Loss in Case of Cable Breakdowns
Today, we are witnessing lots of events in the mining industry which make each manager think about future and review existing industrial safety systems.
Information about what is going on underground helps to avoid mistakes when extracting mineral resources, to optimize control of production processes, to ensure safe and trouble-free operation of the enterprise and to minimize losses caused by emergencies.
Under emergency conditions, the positioning system plays a crucial part. A mining dispatcher has to know who of the workers are within a dangerous area, how many people have left the mine and how many are staying under debris. The positioning system must be able to operate under both normal and emergency conditions, including mines with hazards related to gas (methane), dust and sudden outbursts.
Due to specific features of most communication systems’ architecture, breakdown of at least one cable segment results in loss of data, communication and the possibility of alerting in underground mines. Put simple, the system gets out of order completely.
This defect of the system was eliminated long ago for A71-02 type localized readers.
A solution related to the use of a communication cable for distributed readers is a recent innovation.
A conventional communication cable (RFK-01 type) provides for voice communication and wireless data transmission from the positioning system radio tags based on RFID technology. It consists of a mine design cable provided with a transceiver every 40 meters. The transceiver consists of a PVC pipe, terminal bushings, RFID_tube printed circuit board and heat shrinkable insulating tubes.
The innovative cable (RFK-02 type) contains the same elements but additionally comprises some reserve batteries that maintain power of the cable transceivers and supply circuits.
Stand-by power supply in A71-02 localized readers and RFK-02 distributed readers allows accumulating data about positioning even in case of a power failure or a cable breakdown. After power recovery, data are transmitted to the system.
Active autonomous operation time is about 10 hours (8 hours in case of heavy use). Stand-by power supply to transceivers is provided for by lithium-ion batteries with the capacity of 350 mAh and rated voltage of 3.7 V. A battery of the kind is provided inside each transceiver.
Charging is controlled by DKD11 data concentrator which prevents exceeding of the maximum value of utilized current at a port by means of limiting the number of transceivers being charged simultaneously.
If a system does not have any batteries inside reading devices, the reading devices become non-operating, meaning they cannot read information. People who are supposed to be monitored can leave the area or, vice versa, arrive there, and the information will not be registered by the software. After the function recovery, it will require at least one shift to let the system determine the exact number of people present in the monitored area.
The communication cable based positioning system is designed to eliminate a possibility of data loss in case of a power failure or cable breakdowns. After the system starts operating again, the accumulated data are immediately transmitted to the server for evaluation. As a result, the system starts working with correct data in just a few minutes after restoration.