Electric power cables – whatever happened to the factor of safety? by R Hardie, Aberdare Cables

Good engineering design has always incorporated factors of safety. For mechanical design, the maximum design load would typically range from 25% of the ultimate tensile strength of the material, up to perhaps 70% of the ultimate tensile strength. In civil engineering, the factors of safety are sometimes even more conservative, for example in the design of concrete structures.

Abbreviations
PVC - Poly Vinyl Chloride
RMS - Root Means Square
XLPE - Cross Linked Polyethylene


About the author
Dick Hardie has his BSc Electrical Engineering and is a PrEng with ECSA. He currently holds the position of technical marketing manager at Aberdare Cables. Dick can be contacted on (011) 456 4413.

Light and invisible
Underground transmission with HVDC Light
by D Ravemark and B Normark, ABB

When power must be transmitted over long distances, overhead lines (OHL) have long been the prevailing technology. The costs and performance of buried cables made them unattractive as an alternative. The advent of HVDC Light is bringing about a huge change. Whereas buried cables are not suitable for long-distance high voltage ac transmissions, the different behaviour of dc fundamentally changes this.

Take note
• HVDC makes the use of underground cable viable in many applications.
• Underground HVDC cable offers numerous advantages that include both environmental and technical considerations.
• New HVDC technology has made underground options technically and economically viable.


About the authors
Dag Ravemark specialises within the ABB Corporate Research Department in Sweden. He can be contacted on dag.ravemark@se.abb.com.
Bo Normak specialises within the ABB Power Technologies Department in Switzerland. He can be contacted at bo.normark@se.abb.com.
For local enquiries call Andrew Williamson at ABB SA on (011) 236 7171 or andrew.williamson@za.abb.com

Measuring currents up to 5 A directly Flexible cable for robotic use Slipdac makes for easy wiring An end to 'corkscrews' and breaks in wire shielding Greenlee voltage detector IO modules offer solution for analogue signals Universal tapping connectors Cables for harsh environments Circuit breakers that offer safety, flexibility and easy installation Fleximark thermal printer HVTest supplies cable fault locator vehicle

Automation of a cheese manufacturing facility
by W Kotze, Automation Works, M Bandini and W van der Merwe, Bandini Cheese

South Africa, like many other countries with a growing economy, is looking for opportunity and example when it comes to improving efficiency and production quality. This article considers the challenge of automating a cheese manufacturing facility with emphasis placed on a hands-on process where great value is associated with that personal touch.

This article explores the automation of the Bandini Cheese Factory in Roodepoort, Gauteng by Automation Works in Pomona, Kempton Park.
Take note
• You don’t have to lose the ‘personal touch’ when automating.
• The visibility of process parameters retains the feeling of ‘control’ over the process to the producer.
• Implementing an automation system in the dairy industry requires specialist knowledge and skill of the processes in this industry.


About the authors
Wynand Kotze has his T4 in Electrical Engineering Light Current. He has been the owner of Automation Works for six years.
Morris Bandini has his B.Sc Mechanical Engineering (Wits University). He has been a director of Bandini Cheese for 23 years.
Wilma van der Merwe is a process flow specialist and has her B.Ing Mechanical Engineering (RAU). She has been the engineering manager of Bandini Cheese for 18 months.
Wynand can be contacted on (011) 396 1581 or wynand@autoworks.co.za.

Who is Boss Man? And that avocado green carpet!
by WJ Steenberg, freelance senior instrumentation engineer

There are people I like, there are people who I respect, there are people I admire, and then, there are people that irritate me and people who leave me cold. I have, however, richly borrowed characters, experiences, sayings, idiosyncrasies and mannerisms from all of these, to add colour to the earlier articles and the subsequent parody of the young instrumentation engineer doing his first project.

Take note
• Were you being referred to at all?
• Take life’s lessons into your workplace.
• Work can be fun.


About the author
Bill Steenberg is a qualified industrial instrumentation mechanician and holds a National Technical Diploma in Industrial Instrumentation and Control Systems. He has 26 years experience in the chemical, petrochemical, mining and metallurgical process industries and is a freelance senior instrumentation engineer. He is also on the SAIMC committee for the Johannesburg branch, and serves on the Council of the SAIMC.
Bill can be contacted on 083 949 8104.

Build a soccer stadium in 3 years
ELECTRICAL PROJECT PLANNING AT ITS BEST
by G Badenhorst, Eplan

With the FIFA Soccer World Cup 2010 fast approaching, preparation, design and construction is under way for erecting new soccer stadiums in South Africa. Each proposed stadium is indeed a great project to manage. In the USA, the Project Management Institute’s (PMI) Project Management Body Of Knowledge (PMBOK) has identified four core elements which determine the deliverable objectives of any project, namely: scope, time, cost and quality. As was shown with the recently completed Allianz Arena in Munich, these objectives can be met, as long as the correct tools are used!

Take note
• It’s all about scope, time, cost and quality.
• The key to proper planning is use of the right tools.
• The Allianz Arena in Munich is a 66 000 seater stadium and was built in under three years.


About the author
Gerhard Badenhorst received a B.Ing. degree in electrical and electronic engineering from RAU in 2002. After several years of commissioning in the packaging industry, he has joined the Eplan team in South Africa, providing consulting, services and support.
Gerhard can be contacted on (011) 840 0849 or info@eplan.co.za, also go to www.eplan.co.za for more information.

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Maintenance of medium voltage switchgear
by FD Bolota, Alstom South Africa


This is the first part of an article that will look in-depth at the topic of medium voltage (MV) switchgear maintenance. Initially we will consider what maintenance is and how best to resource your plant to properly maintain its system. Thereafter, we will consider case studies and the detail of how to maintain switchgear.

Take note
• Most failures can be attributed to human error or inadequate maintenance.
• Maintenance can be preventive or interventive.
• A maintenance programme must be in place.
• Maintenance impacts directly on human safety.

Fieldbus intrinsically safe concept (FISCO)
Part 2: Power supplies
by P Saward, MTL UK

Previously we introduced the basis of FISCO [1]. In this article we will consider in detail the requirements of power supplies.
FISCO power supplies are designed to meet the requirements of the International Electrotechnical Commission (IEC) technical specification IEC 60079-27 and provide power and the signal repeater function for an Intrinsically Safe (IS) bus designed in accordance with that specification.

Take note
• FISCO power supplies must meet the requirements of IEC 60079-27.
• The FISCO power supply produces and IS supply to the trunk.
• LED indication clearly shows the status of a FISCO power supply.


About the author
Phil Saward currently holds the position of product manager for fieldbus products at MTL in the UK. MTL is locally represented by Extech Safety Systems.
For more information locally contact Gary Friend on (011) 791 6000 or garyf@tempcon.co.za.

Fieldbus intrinsically safe concept (FISCO) Part 2: Power supplies by P Saward, MTL UK Previously we introduced the basis of FISCO [1]. In this article we will consider in detail the requirements of power supplies. FISCO power supplies are designed to meet the requirements of the International Electrotechnical Commission (IEC) technical specification IEC 60079-27 and provide power and the signal repeater function for an Intrinsically Safe (IS) bus designed in accordance with that specification. Take note • FISCO power supplies must meet the requirements of IEC 60079-27. • The FISCO power supply produces and IS supply to the trunk. • LED indication clearly shows the status of a FISCO power supply. About the author Phil Saward currently holds the position of product manager for fieldbus products at MTL in the UK. MTL is locally represented by Extech Safety Systems. For more information locally contact Gary Friend on (011) 791 6000 or garyf@tempcon.co.za. Fieldbus intrinsically safe concept (FISCO) Part 2: Power supplies by P Saward, MTL UK Previously we introduced the basis of FISCO [1]. In this article we will consider in detail the requirements of power supplies. FISCO power supplies are designed to meet the requirements of the International Electrotechnical Commission (IEC) technical specification IEC 60079-27 and provide power and the signal repeater function for an Intrinsically Safe (IS) bus designed in accordance with that specification. Take note • FISCO power supplies must meet the requirements of IEC 60079-27. • The FISCO power supply produces and IS supply to the trunk. • LED indication clearly shows the status of a FISCO power supply. About the author Phil Saward currently holds the position of product manager for fieldbus products at MTL in the UK. MTL is locally represented by Extech Safety Systems. For more information locally contact Gary Friend on (011) 791 6000 or garyf@tempcon.co.za.

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Steam – Its role in the organisation
information supplied by B Brooke-Taylor, Spirax Sarco

Previously we considered the benefits of steam and why it is still used at all [1]. But these benefits are not necessarily of interest to all users – so in this article we attempt to consider the role of steam as viewed at the different levels of your organisation.

Take note
• Steam is a problem solver.
• Steam is efficient.
• Steam gives up its heat at a constant temperature.
• Steam systems are reliable and rugged.


About the author
This article stems from 75 years of grass roots field experience. Many people, past and present, are responsible for the quality of this information, predominantly Albert Armer (rtd) who still advises on technical issues. The latest incumbent is Phil Stockford, I Eng. MIET, who first joined Spirax in 1980 and has spent the last 10 years collating information to their present status. Bobbie Brooke-Taylor is the local contact for the article.
Bobbie can be contacted on BobbieBrooke-Taylor@za.spiraxsarco.com.

Choosing the right pressure sensor
by F van der Westhuizen, Switches International

Typically, hydraulics and pneumatics operate faster and more often, with higher pressures and temperatures. Accordingly, the pressure sensors have to be more reliable and rugged in order to reduce downtime.
In choosing the correct pressure sensor for your application, you must consider several specifications. You must decide which type of pressure sensor will give you the best results in your application.

Take note
• There are five basic types of pressure sensor.
• The sensor that will best suit your application must be chosen.
• The critical aspects to check are the electrical output, the accuracy, the operating environment and the mechanical coupling.


About the author
Francois van der Westhuizen provides technical and sales assistance at Switches International. They promote the BD Sensor range of pressure sensors. He can be contacted on (011) 462 4253 or francois@switches.co.za.

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