In recent years, utility and industrial sites have been moving over to Ethernet networks to run the automation across the site, due to the flexible, open standards created within Ethernet. Ethernet allows different vendors to all communicate using a common standard, such as the way a connection between devices is created or the way the data is packaged to be transferred between those devices and how it is put back together or reassembled. Using Ethernet means that the whole site can be connected by a single network, allowing remote configuration and control, as well as quicker response times within the control environment and helping to troubleshoot problems on the site. The physical medium being used to transmit the data is the first building block in the Ethernet model, and there are a wide variety of mediums on offer. The most commonly used medium is copper (Category 5e or 6) and fibre-optic cables. Copper cabling has a maximum distance of 100m without EMI (Electro Magnetic Interference) and so is generally used within a single cabinet/building. Fibre optic cabling, on the other hand, can reach up to about 100km per run between devices/repeaters (Depending on the equipment and type of fibre cabling being used) and so is more often used for linking the communications for buildings/sites/substations/mine or plant levels together.
The costs of the cables and installation can be extremely high, especially in harsh environments. In most industrial and utility installations a protected type of fibre optic cable called Ruggedized cable is used. This cable is wrapped in a protective PVC sheath which provides extra protection against elements that could damage the cable (Such as wear and tear or exposure to the elements). When using copper cabling in substations it is necessary to use F/S/TP (Foiled/Shielded Twisted Pair) cabling; this provides protection against EMI which can cause data loss or corruption or even cause equipment failure in certain environments.
It is recommended to use one or more fibre optic pairs to join core segments of the network, however in some cases there may be a remote location with only 1 or 2 end devices, such as a small rural substation or an overflow dam. In these scenarios the cost can be extremely high to purchase and run standard copper or fibre cabling for a small number of devices. When this is the case one looks at using cheaper alternatives, whilst still requiring the stability and reliability of hardened industrial or utility grade equipment.
One alternative to these more common communication mediums is to use WiFi devices. These devices communicate using radio signals and thus have no need for physical cabling. Installing wireless involves more planning than installing cables, as site surveys are required to determine where devices will need to be installed in order to provide coverage to the correct locations. Other factors include determining if there is correct line-of-sight between antennas and scanning to find out what other devices in the area could be using the same frequencies, thus causing unwanted interference.
One example of this is when H3iSquared was contracted to install a WiFi solution so as to get communications between a coal mine’s control room and an overflow meter at a remote dam 3km’s away. Communication was also required between a stacker and reclaimer in the field, both of which could move up and down up to 1 km of railway tracks. This was to complete the interlocking of these two machines so as to prevent physical collisions. H3iSquared concluded a site visit and determined that there were too many obstacles such as process equipment, structural buildings and even changes in the lands topography. These were factors illustrating the impracticality of using wired communications due to the time and cost that would be involved in running cables routes. For this reason a solution was required that would be part WiFi links and part wired.
In this scenario there is only one IED at the remote dam that needed to be linked to the rest of the network, however this IED is critical. Prior to installing this WiFi solution when a pump needed to be started or stopped an engineer would need to be called out and make the trip to the dam. With this installation the IED at the dam can be monitored and controlled remotely, meaning engineers can be more proactive and waste less time on travelling for a single IED.
WiFi can be a great alternative to using cabling, however it is quite dependant on a few different factors, mainly obstructions of the links, interference caused by EMI or other WiFi devices in the area. For places where WiFi is not feasible and standard Ethernet cabling is too costly, RuggedCom has developed its EoVDSL (Ethernet over VDSL) range of products. EoVDSL is a technology that can utilise single untwisted pair cabling (Such as telephone cables) to transfer Ethernet up to 4kms; with top bandwidths of up to 40 Mbps. This means that in many scenarios existing cabling can be utilised, meaning installation costs are minimised. EoVDSL can also be used in areas where obstructions limit the use of WiFi devices, or in extremely dirty/dusty areas where splicing of fibre optic cables is not practical.
Due to RuggedCom’s modular design of its devices, many different communication methods can be combined into a single unit. For instance a unit can be built with 6 normal copper ports for IEDs, a wireless module for engineering access or a wireless link, and an EoVDSL port to connect this remote section to the rest of the control network up to 4km’s away. With this kind of flexibility a unique tailored solution can be built for just about any solution the end user requires, whilst minimising the amount of different devices or even vendors required. These solutions are more reliable and budget sensitive as they have less points of failure, and it is cheaper and more feasible to keep a single device as a spare rather than having to worry about 2 or 3 devices per section. RuggedCom devices are built to last, with a standard warranty of up to 5 years, and the option to increase this to 10 years.
For any further questions on the RuggedCom family of products feel free to contact H3iSquared:
- Tel: +27 (0)11 454 6025
- Email: info@h3isquared.com
Website: www.h3isquared.com