Bag filters to remove particulate materials from flue gases are becoming increasingly common. A clean burning smokestack may well be a sign that a bag filter is installed. However, we previously noted that nitrogen oxides are harmful pollutants [1,2], as are sulphur oxides. This article relates to the latter.

Take note
• Many of the most harmful emissions from smoke stacks are invisible.
• Sulphur oxides are harmful pollutants and are removed from flue gas by scrubbers.
• Special magnetic flow meters must be used in the control of limestone slurry fed to the scrubber.

About the author
Rob Oliaro has been the analytical specialist with Yokogawa South Africa since 1996.
He can be contacted on (011) 831 6300.

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If products, particularly capital goods, are going to be profitable in the long-term, it is not only procurement costs that companies have to take into account. The costs of operation, maintenance and unplanned downtimes are also crucial. In drive engineering, for example, the procurement costs only account for an average of between 10 and 15% of the total costs. How high the follow-up costs will be is determined by both intrinsic factors specified at the design and manufacturing stages and the operating conditions during the utilisation phase. Life Cycle Costing (LCC) is a valuation approach that allows for these follow-up costs and can be used as the basis for making decisions for both the development and production of new machines and system components as well as for their procurement.

Take note
• LCC draws up a financial assessment for capital goods based on all costs incurred during their life cycle.
• For drives, only between 10 and 15% of the total cost is the procurement cost.
• LCC allows rational comparison between products or components that may cost less to purchase, but are less to purchase, but are less efficient or reliable than others.

About the authors
Prof Dr Thomas S Spengler is Dean of the Department for Business and Social Sciences, Production Logistics at the Technical University of Braunschweig. Dr Ing Christoph Herrmann is associated with the Institute of Machine Tools and Production Technology at the Technical University of Braunschweig. Prof Spengler and Dr Herrmann were invited to write this article by SEW Eurodrive, who view LCC as a critical tool.
SEW Eurodrive can be contacted locally at (011) 248 7290 or rrose@sew.co.za.

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Whereas wireless-enabled devices are almost commonplace in consumer electronics their use in industry is less well-known. However, wireless-enabled devices are now poised to breakthrough into the process arena. This article explores the background and considers likely future applications for wireless on process plants.

Take note
• Wireless means cost savings on cable and flexible network configuration.
• Wireless monitoring is scaleable, flexible and secure.
• There is no doubt that wireless monitoring can boost plant safety levels.
• Introducing wireless transmitters can free up 20 to 30% of your existing cable cores.
About the author
Neil Hankey is EMEA product marketing manager for field instruments at Honeywell Process Solutions.
Honeywell Process Solutions can be locally contacted on (011) 695 8000 or has@honeywell.com.

Power over Ethernet (PoE) in compliance with IEEE 802.3af offers simultaneous transmission of data and electrical power of up to 15 W via standard Ethernet cabling. This technology is regularly used in industrial Ethernet networks when Wireless Local Area Network (WLAN) access points or Internet Protocol (IP) cameras have to be installed in remote or difficult to access sites, such as factory ceilings and walls. The integration of PoE technology into a managed switch infrastructure offers a variety of advantages besides easier installation.

Take note
• Electrical power of up to 15 W can be transmitted via standard Ethernet cabling.
• PoE was established particularly to cater for IP cameras, VoIP telephones and WLAN access points.
• PoE is suitable for use with a variety of automation components.
• The Phoenix Contact MMS is the first industrial Ethernet switch to feature integrated PoE interfaces.

About the author
James White studied Electrical Engineering at the Bloemfontein Technikon. He currently holds the position of product manager automation for Phoenix Contact Southern Africa. James has vast experience in automation with the focus on fieldbus systems.
He can be contacted on (011) 801 8200.

More and more industrial users feel attracted by wireless networks: flexibility, time saving, cost reduction, simplicity… Dreaming… Well, maybe… from theory to actuality, the subject can become tricky. Especially with industrial applications it becomes very necessary to identify the traps in order to avoid and properly pass around them. In particular, when building wireless networks, many candidates are wondering about such issues as security and reliability, topics which are especially relevant when preparing an industrial application. In this article, we offer an overview of how Frequency Hopping Spread Spectrum (FHSS) technology can assist with overcoming these concerns.

About the author
Bob Petrie is the owner of Throughput Technologies. Throughput Technologies has been the South African representative for Pro-Soft Technology for the past 10 years. Over the past five years, ProSoft’s RadioLinx products, designed for industrial radio systems – have locally been marketed and used in numerous applications in Southern Africa.
Bob can be contacted on (011) 705 2497 or bob@throughput.co.za.

Take note
• FHSS technology can assist in addressing network security and reliability issues.
• Frequency hopping technologies use narrow bandwidths and hop from one frequency to the next.
• The so-called 2,4 GHz band operates from 2,400 000 to 2,483 500 GHz.
• The 2,4 GHz band is an ISM band and is therefore license-free.

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Fossil fuels have always been the primary source of energy for electricity generation. Concerns about the sustainability and greenhouse gases from fossil fuels has led to an increased drive to develop alternative systems to generate electricity. This is further supported by international agreements to reduce the volume of carbon dioxide produced from fossil fuels. Most countries are exploring windmills as a possible source of energy.

Take note
• Wind energy terbines’ energy converters require numerous current transducers.
• Using a closed-loop principle current transducer can be made to react remarkably fast – fast enough to protect semiconductors.
• Current sensors can be developed for special applications.


About the author
The information in this article was provided by Mervyn Stocks on behalf of LEM. Mervyn Stocks is the director of Denver Technical Products, a company that has been responsible distributing LEM power electronic products in South Africa for the past 15 years.
Mervyn can be contacted on (011) 626 2023.

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Incidents of power outages are likely to increase before the situation improves at all. Recognition of the risk of outages affecting business and homes is resulting in a rush to purchase product, which in many cases, instead of adding value can suddenly become a liability.

Take note
• Most reported genset problems relate to poor and faulty installation.
• Installers should be very familiar with the Wiring Code SANS 10142-1.
• It is highly recommended that a genset is purchased with a professional service contract and at least four guarantee services/checks recommended as part of sale.

About the author
Alan Hoffmann currently holds the position of chairman of the Hoffmann Group of Companies. His background began with an electrical apprenticeship and the structuring of business that manufactured alternators, designed and built generating sets for homes, farms, industry and mining throughout South Africa. Alan was the chairman of the Contractors Plant Hire Association in South Africa for several years. The Hoffmann Group was originally established in 1937 and has over the years successfully represented world leading companies and products like Kohler, Miller and Curtis Wright.
Alan can be contacted on sales@hoffmannpower.co.za.

The use of modern enclosed hot aisles to address increasing power densities in the data and control centers has brought into question the suitability of working conditions in these hot aisle environments. In this article, it is determined that the additional heat stress imposed by such high density environments is of minimal concern.

Take note
• International guidelines exist for workers in a variety of environments.
• Increased power densities in control and data centres input on the ambient temperature in the aisles.
• Proper design considerations can ensure that personnel are never exposed to unacceptable temperatures.

About the Author:
Jim Fink is product manager for large systems precision cooling products at American Power Conversion in West Kingston, RI. He holds a Bachelors degree in Electrical Engineering from Union College in Schenectady, NY, and a Masters in Business Administration from University of Rhode Island. He is a registered professional engineer in the state of Rhode Island, and has 10 years of experience in mission critical facilities design and operation.
APC can locally be contacted through Barend Jonker (011) 465 5414 or barend.jonker@apc.com.

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