Energy Efficiency Made Simple Vol IV 2015

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to the network without any benefit. When considering Ethernet for use in substations or other utility sites, the hardware’s resistance to EMI must be considered. EMI can adversely affect transmission of data, especially over copper cables and within the units themselves. Hardware manufacturer It is also important to test functionality of a hardware manufacturer before purchasing. Some Ethernet standards are still quite vague in their exact requirements, or are very general in their requirements, so a manufacturer could correctly and legally offer compliance to a standard that turns out not to be the level of compliance required. A current and relevant example of this is the IEC61850 [2] standard for electrical substations. IEC61850 [2] is not a hard and fast standard, but a collection of standards, best practices and suggestions (regarding both the physical and logical aspects) for running a critical network for substation automation. For this reason, some manufacturers will state their hardware is IEC61850 [2] compliant when in fact it barely complies. From a technical and legal standpoint, the statement of compliance is correct and true. This leads to customers purchasing hardware that is not going to meet their requirements, and thus huge losses of capital time and investment. Avoid vendor lock Another important point when considering which manufacturer to use is to avoid becoming vendor locked where possible. For instance, if you select a certain manufacturer that offers a proprietary form of redundancy you will then be obligated to use that same vendor for any expansions or replacements in the future (unless that vendor offers backwards compatibility with open standards). Switching to a new vendor at that stage would require a lot of work and a possible complete redesign of the network to cater for a different redundancy mechanism. Using an open redundancy standard instead means that in future you simply need any manufacturer that complies with the original open standard. For instance, a power supplier could spend

a few years sequentially upgrading its entire control network across the entire country. If a few years into this upgrade a new technology becomes available that is not supported by the current hardware manufacturer, and the company wishes/needs to use this functionality, all the existing hardware would need to be replaced, even though the majority of it is still new. Using open standards, the option would exist to replace only the hardware on those sections of the grid that require the new functionality, whilst interfacing with the existing hardware where possible. Hardware selection must be considered throughout the planning phase. Hardware should be selected once the network is planned and the requirements are clearly stated, otherwise the hardware selection could limit your network design possibilities. One must consider not only the present, but also future plans for the network and the expansion thereof. If this is not properly considered in the beginning, expansion at a later date could lead to wasted time, effort and investment. For instance, if there are no spare ports, expansion will require additional switches to up the port count on the existing network. If the network is being expanded to add a single IP camera at each substation, with no ports available one would need to consider buying a new switch per substation, just to add a single connection point. Similarly, if the IP structures have not been properly planned and cannot cater for the upgrade, changing these would take a huge effort and possibly include downtime (i.e. loss of production). Topologies of the network The next consideration is the topologies of the network, both the physical and the logical. It is important to note that many of these points would not be done in a linear fashion. For instance, topologies will be affected by the manufacturer chosen and the functionality it has available and will in turn affect things such as routing and redundancy. So all of these points will need to be considered simultaneously to provide the best possible overall solution. The physical topology of the network refers, quite obviously, to the physical layout of the switches

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ENERGY EFFICIENCY MADE SIMPLE 2015