Establishing reliable data communications within mining environments
24 July 2018
Whether recovering metals, coal or gemstones, an extremely competitive market demands that mining operations be as efficient as possible. In this article, Bo Jansson of Westermo looks at the critical role data communications play in mining operations and the absolute necessity of network reliability in ensuring production resilience and staff safety.
Maximising throughput, whilst still maintaining the safety of workers, is critical. Companies must aim for continuous operation and limit the amount of interruptions and unexpected downtime caused by equipment issues or loss of data communications. Failure to do so can have a huge effect on profitability.
To achieve this, essential safety, operational and machinery health data is collected from a broad range of mining machines, equipment and sensors. This is provided to the operations, safety and maintenance teams, enabling them to make informed actionable decisions.
Mines and quarries present incredibly challenging environments for data communications and put extreme demands on network design and hardware reliability. Networks often need to stretch over very large geographical areas, there is a significant risk of damage to cables and networking devices, and the environments they are installed in tend to be very harsh or even hostile. Network infrastructure devices such as switches and line extenders must be able to cope with dust, dirt, water, constant vibration, high electromagnetic interference and even extreme shock.
In open pit mines, fluctuating operational temperatures and humidity are also issues, especially for unprotected equipment or devices installed in unheated cabinets. There are also hazardous area applications where technology choice must be carefully considered.
Networking devices are available that have been designed specifically to meet the challenges presented by mining applications. In fact, some devices with extremely robust characteristics can be bolted directly onto the walls of the mine and will provide reliable communications. Typically, switches designed for these applications are constructed using high-quality components that create 20-year service lives and offer Mean Time Between Failures (MTBF) of over 600,000 hours.
Ideally products that are tested to meet the environmental requirements of the IEC 60068-2 standard should be specified. IEC 60068 is a collection of methods for environmental testing of electronic equipment and products to assess their ability to perform under environmental conditions including extreme cold and dry heat. IEC 60068 offers appropriate severities and prescribes various environmental conditions for measurements and tests.
Reliable networking technology
The latest devices can operate in temperatures of -40°C to 70°C and have sealed enclosures with IP65 (or IP67) ratings able to prevent dust and dirt ingress. For surface mines or quarries with high humidity levels, there are switches with anti-condensation breathable textile membranes built into the switch housing that allow moisture and condensation to seep out, but keep the switch completely sealed from moisture and dirt. M12 connectors with integrated threading ensure reliable and robust cable connections.
There is often an imminent risk of exposure to water flowing along mine walls. Ethernet switches with an IP67 rating can be submerged in water to a depth of 1m for a period of 30 minutes without water ingress likely to cause damage. These devices, also often used in food and beverage applications that are pressure washed to remove waste material, can be installed without additional protective housing, which is important as that is not always an option in mining applications.
Vibration, interference and shock protection
Constant vibration is another major issue in mining operations. Network infrastructure is often installed alongside or on equipment such as conveyor belts, which can severely damage a switch over time. It is important to select devices that have been tested to meet IEC 60068-2-6 and 60068-2-64 standards which focus on vibration. There has been much research and development in this area, primarily due to the demand for Ethernet networks to support rail rolling stock applications. Ethernet switches are also available that have been designed according to the IEC 60068-2-27 standard, capable of withstanding shocks of up to 100G, ensuring they will continue to work even if they are exposed to a nearby blast.
Electronic equipment may also be exposed to electromagnetic interference from ventilation fans and other mining equipment. Typically, the latest networking devices are designed and tested to meet the EMC requirements of the EN 61000 standard – the international equivalent is IEC 61000-4-2 - which focuses on the frequency range 0Hz to 400GHz.
Networks frequently operate in hazardous environments that are highly infused with inflammable components. Explosive atmospheres can be caused by gases, vapours or combustible dusts. With a certain level of concentration of these substances, a source of ignition may be all that is needed to cause a disastrous explosion. Installation of networking devices within hazardous areas requires certified equipment. In Europe and most of the world outside North America, hazardous areas are classified according to the zone system. In this system, zones define the general nature or properties of the hazardous material - essentially if it is gas or dust - and the probability of the hazardous material being in the surrounding atmosphere. Groups define the type of hazardous material and (partly) the location of the surrounding atmosphere.
Mining has its own group I, defined as “susceptible to firedamp (flammable mixture of gases naturally occurring in a mine)”, but it is important to consider that networking devices may be installed in hazardous areas with different classifications and certified equipment must be selected accordingly. Devices must be certified according to EX (European Union) and IECEx (global), and sometimes Div 1 class 2 (USA and Canada).
Networking devices are now available that have a case constructed of an alloy called ZAMAC 5. This has a high zinc content, making it non-sparking when struck with a ferrous metal.
These devices can’t necessarily be openly mounted in a hazardous atmosphere, but it does mean that a flameproof enclosure can be opened, if the power has been disconnected. This enables devices to be replaced without the risk of an accidental spark. Potentially this presents a huge cost saving for an operator who would normally have to bring the device or whole system to the surface, or a safe area, to change or even get access to the networking component.
With the mine face, digging equipment and machines constantly moving, there is a risk of cables being worn out, damaged or cut accidently. Networks must be resilient to cope with this eventuality, with switches and their operating systems able to provide rapid recovering redundant ring Ethernet networks. Should a cable be cut, that means communication is not lost and production can continue. In today’s world, that resiliency requirement extends to network security and switches now offer a host of functions to support greater protection against the threat of cyber-attack.
A practical application of this is described in a case study accessible in Editorial / Case studies on this website.
About the author
Bo Jansson is Network Products Manager at Westermo. He has 40 years of experience working with data communications in industrial applications and has been the product manager for Westermo’s network products since 2003. Bo has extensive knowledge of designing products for use in harsh environments.
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