Electricity + Control October 2018

FEATURES: · Analytical instrumentation · Cables + accessories

· Control systems + automation · Earthing + lightning protection · Pressure + level measurement + instrumentation

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COMMENT

ON THE COVER

FEATURES: · Analytical instrumentation · Cables+ accessories

· Control systems+ automation · Earthing+ lightning protection · Pressure+ levelmeasurement+ instrumentation

You’ll never know what is around the corner unless you make the turn…

I have so far only heard remarkably positive feedback on Electra Mining Africa 2018 – and by this I mean that the general sense visitors got was that the industry is ‘back’. Now, this is not by any means to say that things are going swimmingly well. But each journey begins with a few small steps and I genuinely believe that even just a faint glimmer of light is, in cases like this, a fairly good start. In this regard, it also seems that there is a renewed feeling of hope (and I choose the word carefully) emerging in the mining sector. I have commented in the past on the need for a stable policy environment, and one must begin to wonder if such sta- bility is suspected to be emerging? But what a pleasure to find oneself in- volved in events and discussions where the doom and gloom seem to have moved somewhat further to the back of the mind. It is hard to pin down the actual rea- sons for this sense of hope – but a few things are beginning to happen that may well be pointers to a renewed belief in the future. There seems to be a percep- tible shift in the balance of power at the highest level, and there does seem to be a growing sense that some of the muck from the past will actually end up having consequences for certain people. This in itself is a significant step within the economy. And just perhaps, regular folk are now sensing this encouraging change in the wind, and reacting to it. That aside, I recently had the privilege of visiting Poland for the first time to attend the International Conference on Lightning Protection (ICLP). The conference will be coming to South Africa in 2022. This is re- ally significant, and in many respects a trib- ute to the rich history of lightning research associated with this country.

I am looking forward to that, and ammind- ful that although it sounds as if four years is a long while away, we all know that the date will be upon us in no time at all. I, personally, am thrilled that the ICLP is coming to South Africa, as I am fully aware of the challenge that lightning con- tinues to pose – not just in South Africa, but on the continent. It affects lives, and it affects industry. In this regard it is important to be aware that the Highveld is entering lightning sea- son, and simply hoping that nothing will go wrong is not an acceptable strategy. Everyone who has a responsibility for plant needs to be aware that lightning pro- tection strategies require regular review, and that lightning protection systems re- quire maintenance and upgrading. It bears repeating that a lightning pro- tection system is in reality a sub-set of a heath and safety system – where human safety is paramount, and equipment pro- tection important. It is my fervent desire that, in 2022, when the conference lands on our shores, we will be in a growing economy with a stable policy environment, and that we will be perceived as a safe investment destination by all nations. The tragedy of South Africa has been our inability to create the space for invest- ment and growth. And I think we are be- ginning to turn that corner.

EC_OCT cover.indd 1 9/26/2018 2:58:11PM www.electricityandcontrolmagazine.co.za

Endress+Hauser's Heartbeat Technology for flow, level, temperature and analytical measuring devices delivers a fast

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CONTENTS

12

Features

ANALYTICAL INSTRUMENTATION 4 UV vs IR in diagnostic inspection of lines and substations: Roel Stolper, CSIR

6 Sensor solutions in food safety: Brandon Topham, RET Automation Controls

9 Round Up

CABLES + ACCESSORIES 12 Developing next generation cable accessories: Ruben Grund and Michael Zerrer, Pfisterer

16 Round Up

CONTROL SYSTEMS + AUTOMATION 20 Optimising water transfer system with VSDs: Christo du Plessis, Zest WEG Group

24 Round Up

EARTHING + LIGHTNING PROTECTION 30 Surge protection of substations: Jonathan Woodworth, IEEE

20

34 Round Up

PRESSURE + LEVEL MEASUREMENT + INSTRUMENTATION 36 A wireless solution for tank level monitoring: Information provided by RET Automation Controls

38 Round Up

30

36

Regulars

1 Comment 11 Cover Article 42 Engineering the Future 44 Write @ the back 44 Events 44 Advertisers

2 Electricity + Control

OCTOBER 2018

ANALYTICAL INSTRUMENTATION

UV vs IR in diagnostic inspection of lines and substations

Roel Stolper, CSIR

One of the issues in maintenance of overhead lines and substations relates to better understanding as to what is being revealed during ultraviolet or infrared inspections of equipment and hardware.

Take Note!

1. In simple physical terms, corona is plasma discharge whenever ambient gases are ionised. 2. During the subsequent de-ionisation phase, pho- tons are emitted with emission lines related to the spectral properties of these gases. 1 2

Typical problems on lines Electric utilities and research organisations world- wide have launched programmes to investigate and classify all the typical faults that occur on over- head lines. A past working group within CIGRE, for example, has been dedicated to better under- standing the behaviour of polymeric insulators un- der different environmental conditions. Current inspection technologies Years of experience in line inspection have indi- cated that there is still no single best technology that meets every need, i.e. there is no diagnostic sensor that will detect and locate all the possible different faults that may appear on a line. Given this fact, it is probably correct to state that the ide- al inspection tool is one that integrates different types of sensors into a single instrument. Generally speaking, modern inspection tech- nology can be classified into two main groups: ul- trasound radio telescopes and camera detectors. Both make use of the basic phenomenon that every defect emits radiation (energy in the electro- magnetic spectrum) that can then be detected and recorded by an inspection device. Basic principle of ultrasound detectors A round dish focuses ultrasound radio waves onto an RF detector (microphone) that amplifies and presents any weak signal detected to the operator by means of sound produced by an earphone. Basic principle of camera detectors Light from a source is collected by a lens and pro- jected through a filter onto a detector that converts

the light energy into electric signals. The signals are electronically manipulated into a raster image and displayed to the operator. The images shown in Figures 1 to 6 are from various UV and IR camera recordings of electro- magnetic radiation related to unique defects oc- curring in line components. For example, a simple structural defect (e.g. a cut in a silicone insulator housing or a damaged ceramic disc) generates corona activity due to distortion of as well as in- crease in electric field. Similarly, an internal defect in a composite insulator can result in leakage cur- rent along the FRP core rod, causing heat dissipa- tion. Viewed this way, it is clear that corona and thermal cameras are essentially complementary and that no single inspection technology is inher- ently superior. One can therefore also conclude that, ideally, IR and UV inspection should be con- ducted simultaneously. To demonstrate: Figure 1 shows ultraviolet and infrared recordings of the same object. There is only corona activity present due in this case to sharp edges on the clamps. But there is no heat dissipation, suggesting that corona does not nec- essarily generate heat. UV/IR inspection with single device Corona discharges are detected using a UV de- tector that converts UV radiation to wavelengths that are visible to the naked eye. This same prin- ciple applies to IR heat radiation detected by the IR uncooled micro-bolometre and subsequently converted to wavelengths in the visible spectrum. In simple physical terms, corona is plasma dis- charge whenever ambient gases are ionised. Dur-

There is no diagnostic sensor that will detect and locate all the possible different faults that may appear on a line.

Author: Roel Stolper is an expert researcher in diagnostics with the CSIR.

4 Electricity + Control

OCTOBER 2018

ANALYTICAL INSTRUMENTATION

ing the subsequent de-ionisation phase, photons are emitted with emis- sion lines related to the spectral properties of these gases. Air is made up of about 80% nitrogen, which has its dominant spectral lines in the UVA and UVB spectrum and minor lines in the UVC spectrum. With regards to heat radiation, any material emits at a wavelength that depends on body temperature, its so-called kinetic surface energy. Ac- cording to Wien’s displacement law, peak wavelength, λ max, is at 2898/T, where λ is expressed in micrometres (1.10-6) and T is temperature in de- grees Kelvin. Simple calculation reveals that a body at 27°C emits peak radiation at 10.55 μm such that, for example, a clamp at 100°C will have maximum radiation at 7.76 μm. Calculation shows that, for any line inspection application where there are only low temperature sources, a heat detector is required that con- verts radiation at 8-10 μm wavelengths into the visible spectrum. There are a number of heat detectors available on the market and these are classified according to spectral sensitivity as determined by material com- position of the detector. The mercury cadmium telluride (MCT) and Quantum Well (QWIP) de- tectors, for example, are relatively expensive since Sterling engines are required to cool them to -70°C. The micro-bolometer detector, by contrast, is used by many camera manufacturers for industrial IR inspections. This type of detector does not need cooling and works at room temperature. It is also compact with high pixel resolution, low cost and easy availability. Conclusions UV and IR inspection are not simply two alternative ways to look at the same problem. Instead, each inspection technology records a particular defect or abnormality within the component or equipment being inspect- ed. In general, it can be said that UV recordings indicate the presence of corona activity while IR recordings highlight heat phenomena. Moreover, UV corona recordings have to do with surface discharges and indicate the presence of high electric field. In contrast, infrared measurements high- light the presence of leakage current. The first phenomenon depends on surface condition while the second depends on an internally generated heat source. The latest multi-spectral camera will enable the power industry to si- multaneously inspect electrical equipment for corona discharges and IR hotspots. A specialised software program will assist the camera user to record, process, store and retrieve these recordings.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Electricity + Control

OCTOBER 2018

5

ANALYTICAL INSTRUMENTATION

Sensor solutions in food safety

Brandon Topham, RET Automation Controls

Product recall is costly not only in terms of lost revenue, wasted materials, and production time but also in terms of brand reputation and brand loyalty. The sooner food safety issues can be addressed and mitigated, the lower the risk of a large- scale recall.

Take Note!

1. A label verification tech- nology is critical to ensur- ing that the proper labels are affixed to the right products. 2. Monitoring and docu- menting temperatures throughout the food chain is imperative. 3. Another way to protect against the growth of path- ogens during food produc- tion is to select sensors with hygienic designs. 1 2 3

T his article outlines three of the most com- mon food hazards that can result in recall and describes several sensor technologies that can help ensure food safety in each scenario. Common food safety hazards Three hazards to food safety include undisclosed allergens, pathogens and physical hazards. Choos- ing the right sensor technology for your application can go a long way towards reducing your risk in each of these areas, saving you time and money in the long term. Undisclosed allergens One significant food safety hazard is undisclosed allergens. Food allergies are potentially lethal to the consumer, so it is essential that food packag- ing accurately discloses the allergens present in the food item. By law, eight major foods must be disclosed on packaging: milk, eggs, fish, shellfish, tree nuts, peanuts, wheat and soy. However, one error that can occur during the processing of packaged foods is when a product is placed in the incorrect packaging, resulting in in- accurate labelling of food contents. For example, if a cheese-stuffed hot dog is accidentally packaged in a regular hot dog packaging, the package would not include the required milk allergen warning. Solution: vision sensor for label verification A label verification technology is critical to ensur- ing that the proper labels are affixed to the right products. One very effective technology is a vision sensor, which can be used to verify the presence of the correct label on the packaged food item.

For example, bottle filling lines run many dif- ferent types of products and require frequent changeovers. To prevent mislabelled bottles and ensure quality and food safety, a vision sensor can determine whether a label pattern matches a reference pattern taught to the device. Automat- ing label inspections with a reliable vision solution improves quality control by reducing the risk of er- ror common to manual inspections, which in turn helps reduce the incidence of product recall due to undisclosed allergens.

Pathogens (biological hazards) Pathogens are another significant food safety concern. Also referred to as biological hazards, pathogens are any type of bacteria, virus, or para- site (such as listeria or salmonella) that can cause illness to humans if consumed. Pathogens can be

6 Electricity + Control

OCTOBER 2018

Solution: hygienic sensors with remote temperature monitoring capabilities Monitoring and documenting temperatures throughout the food chain is imperative. Howev- er, manual documentation can be costly, requiring significant investments in time and resources. An IIoT solution to this problem is wireless tem- perature sensors. Wirelessly-connected tempera- ture sensors can be used to automate the docu- mentation process by wirelessly transmitting data through a controller. Not only does this solution allow for historical data to be stored and accessed in the future, but it also allows for real-time condi- tion monitoring. This means that, if the temperature of a food storage area rises above a set threshold, instant alerts can be sent, warning a manager that tem- perature requires adjustment. These alerts can be made viewable in the HMI, sent via text message, and/or set to initiate a warning signal on a tower light or other visual indicator. The ability to identi-

introduced to food products in several different ways before, during, or after food processing. While there are many points at which biological hazards can be introduced, temperature change is one of the most critical conditions for pathogen growth. For example, when lunch meat products are not lowered to the proper temperature quickly enough, or are not maintained at the correct tem- perature after processing, harmful bacteria will be allowed to grow. Ensuring that temperature levels remain appropriately controlled at all points – from food processing to distribution – can help prevent many biological hazards from reaching harmful lev- els. In addition, pathogens can be introduced if ma- chine components come into frequent contact with food. Components without a hygienic design (e.g. deep grooves where food can become lodged) may not be easily cleaned even with rigorous washdown practices and can become a food safety risk.

fy potentially dangerous temperature changes as they occur can help pre- vent product spoilage and save costs. In addition to remote temperature monitoring, another way to protect against the growth of pathogens during food production is to select sensors with a hygien- ic design. Any sensor that regularly comes into direct contact with food must be FDA-rat- ed. However, this rating is not required of the many sensors that do not typically come into direct contact with food.

Electricity + Control

OCTOBER 2018

7

ANALYTICAL INSTRUMENTATION

In some cases, it may still be possible for food to make brief contact with the sensor and then return back into the process. In these cases, a hygienic sensor – with minimal crevices is a must. Physical hazards Physical hazards refer to potentially harmful, non- food particles that end up packaged with the food, often due to breakage of mechanical parts on the machine. While metal detectors can identify small pieces of metal before the product is distributed, other materials such as plastic and glass could slip by unnoticed, risking the health of the end custom- er if they consume a foreign object in their food. Sensors are not the only machine components from which pieces can break off and fall into food, but they are still important to consider. In environ- ments with frequent washdown, it is important to ensure that the product is rugged enough to withstand high temperatures and pressure, and a high chemical resistance may also be necessary to withstand caustic cleaning solutions. In these applications, look for an IP69K-rated sensor that has been thoroughly tested to withstand harsh environments. Solution: rugged sensors with all plastic housing

In addition, the material construction of the sensor makes a difference. While stainless steel might seem like the intuitive choice for food appli- cations, a metal photoelectric sensor will always still have plastic components (e.g. window, light pipes, etc.) that can become dislodged and fall into the process. Because sensors with metal housing still contain some plastic, this means they have plas- tic-to-metal joints that are attached either by ad- hesive and/or mechanical means. When subjected to temperature change – such as during cleaning – the different materials expand and contract at different rates, creating small air gaps which leave room for water ingress. On the other hand, a photoelectric sensor made entirely of plastic has plastic-to-plastic joints that are ultrasonically welded together, becoming a single piece. This reduces the risk of the sensor window becoming dislodged, and the sensor is better protected against the ingress of water.

The sooner food safety issues can be addressed and mitigated, the lower the risk of a large-scale recall.

Brandon Topham is a Director at RET Automation Controls.

8 Electricity + Control

OCTOBER 2018

round up

ANALYTICAL INSTRUMENTATION

Ultrasonic sensors for switching and measuring

the detection of the smallest of objects or the detection through the smallest of apertures at short response times. Countapulse Controls is the official distributor for Leuze sen- sors in southern Africa and is able to offer technical support in- cluding assistance in selection of the most appropriate sensors for any given application. Enquiries: Gerry Bryant.Tel. +27 (0) 11 615 7556 or email bryant@countapulse.co.za

Longer operating ranges and broader areas of application are only two of the features offered by the Leuze HTU 418B and Leuze DMU 418B ultrasonic sensors. Suitable for switching and meas- uring applications, these devices have an operating range of up to 1 300 mm. These fully metal-enclosed ultrasonic sensors offer protection to Class IP 67 and are available in either cylindrical M18 or M30 housings. The compact housing allows the sensors to be installed in locations where there are space constraints, and this offers end-users greater flexibility. Both series were equipped with an improved teach function: two push buttons for defining two independent switching points simplify setup and increase flexibility when using the sensors. De- vice types with an IO-Link interface ensure the intelligent, simple and user-friendly connection and activation of the sensors. Temperature compensation prevents measurement errors that could be caused by various environmental conditions. Four op- erating modes, e.g. for changing from synchronous to multiplex operation, offer high flexibility during use. The ultrasonic sensors operate using a switching behaviour that is largely independent on the surface of the sound-reflecting materials.They are available with various sound lobes, i.e. with dif- ferent opening angles.The narrow sound lobes in particular permit

Electricity + Control

OCTOBER 2018

9

round up

ANALYTICAL INSTRUMENTATION

WEG Motor Scan set to change industry

Leveraging digital technology is said to be key to participating in the next wave of economic growth. At the very least, using it will allow mines, process plants and other industrial operations to re- duce operating costs. Fanie Steyn, manager rotating machines at Zest WEG Group, says one of the areas that stands to be most impacted is predictive maintenance. “This is where access to accurate data can be used to increase production efficiency and reduce downtime and, for the first time, industry will be able to do this remotely with electric motor installations,” he says. WEGMotor Scan is a brand new solution available from ZestWEG Group that facilitates remote monitoring of electric motor installa- tions. This innovative technology allows engineers and maintenance personnel to make informed decisions about the health of installed motors and react accordingly, depending on the data captured. Steyn says that theWEG Motor Scan solution uses Industry 4.0’s digital technology including the Internet of Things (IoT) and big data analytics. The technology allows for the monitoring of running hours, measurement of vibration and surface temperature as well as provid-

ing data on speed and start/stop time. The load and efficiency will be included in the second phase. Data is extracted via Bluetooth using a smart device with the innovative app that is available on android and iOS phones and tablets. Users can also access the data on laptops and desktops via a dedicated web portal. Powerful analytics help to process the data and predict pending failures or hidden problems based on frequency spectrum analysis. Warning levels are pre-set based on acceptable baselines of temper- ature/vibration and sophisticated software is able to plot performance curves with the captured data. The data is sent to the cloud for stor- age facilitating fast access and more accurate decision making. “Using the WEG Motor Scan solution minimises the require- ment to manually collect and monitor data, and it eliminates the guesswork from preventative maintenance routines. This removes the inefficiency of reactive maintenance and assists in minimising motor failure,” explains Steyn. WEG Motor Scan solution is currently available for frame sizes from 63 to 450, providing this innovative monitoring solution for motors ranging from 0,18 kW up to 1250 kW. It can be fitted on newly manufactured motors or retrofitted to existing installations. The sensor itself is battery powered and has an estimated life span of three years. It is designed to work in ambient tempera- tures ranging from -40°C up to 80°C, has a protection rating of IP66 and can operate in Zone 1 areas with a T4 temper- ature rating. Offering optimum flexibility, the sensor can be used on direct online starting as well as variable speed drive (VSD) applications.

“This is a major value add for our customers and the market and will in reality set a new benchmark in pre- dictive maintenance,” Steyn concludes. Enquiries: +27 (0) 11 723 6000 or email marketing@zestweg.com

Next generation self-contained barrel-mount sensor

The new T18-2 photoelectric sensors have an FDA-grade shatter- proof plastic housing and are IP69K-rated and ECOLAB™ certified to protect against water ingress and chemical wash-down. TheT18-2 Series sensor is designed to hold up to high-pressure, high-temperature wash-down. The epoxy fill eliminates internal air cavities in the housing that can lead to condensation inside sensors during temperature cycling. The sensors have been tested by ECOLAB to certify that they resist damage when exposed to common cleaning chemicals. The plastic used throughout the T18-2 is made of FDA-approved, shat- terproof plastic for use on food production lines. Crevices have been minimised to eliminate debris build-up. The knurls have also been removed from the nut, and the light pipes have been over-moulded for easy cleaning. All labels have been removed and replaced with permanent laser etching. Installing the nut, option- al seal kit, and bracket will cover all exposed threads on the nose. Ultrasonic welding is an advantage of using an all-plastic hous-

ing and creates a superior joint. Metal sensors contain plastic win- dows and other components that are joined mechanically or with adhesives. The joints are then subject to thermal shock because the metal and plastic components expand and contract at different rates, creating small gaps and allowing water inside the sensor. Ultrasonic welding fuses plastic components into one solid piece of durable plastic that is not affected by thermal shock. Features • Highly visible output and dual-function power and stability indi- cators. • Laser etched markings for longevity. • Powerful and bright visible red emitter for easy alignment and setup, excluding IR models. • Operates in temperatures ranging from -40 to +70 °C. • 4-pin M12 Euro-Style connector is IP69K wash-down rated. Enquiries: BrandonTopham. Email Brandon.topham@retautomation.com

10 Electricity + Control

OCTOBER 2018

COVER ARTICLE

FEATURES: · Analytical instrumentation · Cables+ accessories

· Control systems+ automation · Earthing+ lightning protection · Pressure+ levelmeasurement+ instrumentation

Taking the pulse of your measurement

EC_OCT cover.indd 1

9/26/2018 2:58:11PM

T hrough a clever combination of diagnos- tic, verification and monitoring functions, Endress+Hauser’s Heartbeat Technology for flow, level, temperature and analytical measuring de- vices enables safe and cost-effective plant oper- ation throughout the entire life cycle. Permanent diagnostics of the process and measuring devices guarantee efficient maintenance as well as safe plant operation. Verification takes place without in- terrupting the process, thus eliminating the need to remove the instrument. You have the certainty of knowing that your process is running safely and reliably while your testing costs are significantly reduced. In addition to these cost savings, the trend identification feature allows you to discover the potential for further process optimisation. Diagnostics with Heartbeat Technology Using the diagnostic capability of Heartbeat Tech- nology, field devices can monitor themselves continuously and output standardised diagnostic messages with instructions. The device status is always displayed, enabling you to adopt a sta- tus-oriented maintenance strategy. Status signals are classified in accordance with VDI/VDE 2650 and NAMUR recommendation NE 107. Additional corrective measures are displayed in full text, enabling you to direct maintenance

personnel to respond quickly with the necessary measures.

Verification with Heartbeat Technology Using Heartbeat Technology, you can verify that your measuring devices are functioning correctly while they are installed. A simple, guided test pro- cedure provides a clear ‘Pass’ or ‘Fail’ statement, which is documented in an automatically generated test report. This test function is integrated in the measuring device and is available via all operating and system integration interfaces. So, you can ver- ify anytime anywhere, thus saving time in the field. Monitoring with Heartbeat Technology New device-specific trend parameters within the monitoring function of Heartbeat Technology make predictive maintenance possible. With Heartbeat Technology, you optimise maintenance planning and perform target-oriented service according to the actual need. When compared with reactive maintenance, predictive maintenance allows you to realise higher plant availability and reduced product loss. With Heartbeat Technology you achieve effective predictive maintenance for the measurement fields of flow, level, analysis and temperature. You can plan maintenance work eco- nomically and avoid plant downtime.

Enquiries: Natlee Chetty. Tel. +27 (0)11 262 8007 natlee.chetty@ za.endress.com For more information: www.za.endress.com/en

Electricity + Control

OCTOBER 2018

11

CABLES + ACCESSORIES

Developing next generation cable accessories

Ruben Grund and Michael Zerrer, Pfisterer

Power distribution networks are changing rapidly as integration of renewables and creeping urbanisation require updated concepts in power infrastructure.

Take Note!

1. Modern cable joints en- sure simple installation of the waterproof exter- nal housing as well as 2. Treatment of the cable shielding can be adapted individually for cable type and customer needs.

C ompactness is no longer only a desirable but a crucial performance requirement. Similarly, downtime has to be minimised while safety aspects are more complex. Increasing transmission capacity Urbanisation requires higher transmission capaci- ty that could be either triggered by increasing cus- tomer numbers or fluctuating power generation and consumption due to integration of renewa- bles. Moreover, energy has to be transported over long distances since points of generation and de- mand often do not overlap. This requires detailed consideration of power losses and one approach to reduce these has been increased system volt- age, as has occurred over past decades. While the first three-phase ac line in 1891 had a system volt- age of 25 kV and carried power over 176 km, these days system voltage of 550 kV is used for extra high voltage cable lines, allowing power transmis- sion up to 1.5 GVA. The main reason for higher system voltages is power loss reduction. For ex- ample, increasing system voltage by 10 leads to a reduction in power losses by a factor of 100, using same diameter cable. If cable diameter is reduced

by 10, power losses are still reduced by a factor of 10.

Cable accessories up to UM=550 kV Accessories are increasingly available for high volt- age cables up to 550 kV. These include dry, plug- gable cable connections for transformers and gas insulated substations (GIS), cable terminations, cable joints and pluggable cable joints as well as blind dummy plugs. These components are type tested and can be used for all types of XLPE cable, independent of core diameter, thickness of insu- lation or manufacturer. All field control units and electrically stressed materials are pre-fabricated and routine-tested, which ensures highest long- term operational safety. Pluggable systems One type of dry pluggable system can handle cable diameters of 3000 mm² CU or AL conductor, carry- ing up to 4000 A nominal current. Maximum diame- ter over insulation is 144 mm. An additional benefit is the housing, which is touch-proof, waterproof and salt-water resistant, meaning it can be used in coastal areas as well as in offshore surroundings.

12 Electricity + Control

OCTOBER 2018

CABLES + ACCESSORIES

tor length also changes leading to elongation and therefore a ‘buckling’ effect at high temperatures. The smaller the conductor, the greater this effect.

Energy has to be transported over long distances since points of generation and demand often do not overlap.

Figure 1: Example of pluggable system UM=550 kV.

Cable joints Modern cable joints ensure simple installation of the waterproof external housing as well as maxi- mum operational safety. Using a bolted connector allows the conductor to be connected with optimal contact force, without special tools. Treatment of the cable shielding can be adapted individually for cable type and customer needs.

Figure 3: Example of set-up for IEC type test.

To prevent buckling of the cable inside the termina- tion’s insulator housing, a special spring device has been integrated, as shown in Figure 3 . This allows for length compensation of the conductor inside the termination and at the same time prevents the conductor from moving off-centre, thereby also ensuring a constant field distribution, independent of temperature change. As in other terminations, the base plate is insu- lated from the cable screen, which allows a flexible earthing system according to customer require- ments. To allow quick and safe cable connection, the top bolt of the termination as well as the con- nection in the joint is equipped with a bolted con- nection that does not require any special tools. This bolted connection offers life-long contact force and assures the connection to the cable connector. A new cable clamping system has been devel- oped for both the cable connector and termination, consisting of mainly two parts; an extension cage and a cable clamp. If the system is to be used on small outer cable diameters, an additional adapt- er is available. The cable clamp is adjusted on the cable diameter to allow maximum retention force, ensuring minimal pressure on the cable. As such, even huge cable weights can be handled. At the same time, this system fulfils a centring function to ensure proper positioning of the cable within the connector-respective termination.

Figure 2: Example of cable joint UM=550 kV.

A major hurdle is the so-called Annex G test at which the joint is submersed in water at 1 bar pressure and cycled, with the number of cycles depending typically on regional specifications. Outdoor cable terminations Another key component in modern cable networks is the outdoor termination, now usually offering a water-repellent external housing made of silicone. Minimum creepage distance is 16 600 mm which covers a high pollution class of > 65 mm/kV. The stress cone of the termination is also pre-mould- ed and routine tested, which allows fast mounting time and ensures high reliability of these parts. A special centring device, unique to some types of terminations, ensures the right position of the stress cone, both in radial position and with the axial centricity of the important electrical part. A major hurdle for outdoor terminations is over- all size, resulting in a large free length of cable in- side the termination. Due to load change, conduc-

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OCTOBER 2018

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CABLES + ACCESSORIES

investment is not equivalent to the benefit. Chart 1 compares use of different conductor types and shows the resistance increase with reference to the skin effect. The ratio of ac resistance to dc re- sistance is shown to be close to equivalent utilis- ing enamelled conductors, which are stranded and have every single wire insulated. Therefore, no cur- rent flows between the single strands, resulting in a great reduction of skin effect. This is a major advantage for cables but it chal- lenges design and therefore the function of cable accessories. Contact surface requires homogene- ous current distribution. Former solutions required removal of insulation layers by abrasives or heat, processes which are time consuming and are dependent on workmanship. Furthermore, addi- tional cable length is required due to the bending of strands. This therefore contradicts the goal of compact solutions. Some of the latest develop- ments make use of the front surface of the cable conductor as the connecting surface. Contact sur- face is offered with an incompressible yet flexible material. This solution is being used for joints, ter- minations and pluggable systems. Flexibility While increase in transmission capacity is a vital enabler for the grid of the future, network flexibility is another key aspect. Pluggable systems are be- coming more and more popular but any enclosed system, such as a cable system, needs additional thought when it comes to protection. Surge protection Surge arresters are usually either SF6 or air-insulat- ed and both have limitations. Use of SF6 is becom- ing more restricted and testing requires handling SF6 gas. Similarly, air insulation requires creepage and space and positioning is not optimal. Substa- tion grid layout when using cable usually does not allow an air-insulated arrester to be positioned as close to the transformer as possible. A pluggable, solid insulated arrester has been developed and tested up to Uc=144 kV (Ur=180 kV) with reference to the latest standards. The arrest- er’s main insulation is solid and there is no insula- tion liquid or gas such as SF6 included. The most important parts as far as arrester functionality is concerned are the metal oxide discs. These are used as a non-linear component with very low leakage current during operation.

Figure 4: Compensation device.

Figure 5: Cable clamp.

Decrease in skin factor De-centralised energy production, driven mostly by increasing generation of renewables, requires additional network capacity for energy transfer and distribution. Growing urbanisation further drives this by requiring additional distribution capacity. Increasing conductor cross-section is one op- tion. Nevertheless, due to the ‘skin effect’ the

Chart 1.

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all options without oil work and no need to open the transformer tank. The system can be tested using testing equipment – voltage-proof enclosed and connected to a cable system using cable con- nectors or connected to an overhead line utilising pluggable bushings. These pluggable bushings are available up to UM 245 kV and solutions for higher voltages are under development. While pluggable bushings are advantageous with regards to trans- formers, other applications are made possible with this approach. One example is a temporary instal- lation for short- or mid-term applications where downtime is crucial and full flexibility is required. All components are pre-tested and shipped to site and final assembly is but a plugging process. Evolution of cable terminations The major proportion of all cable terminations to- day are oil-insulated and consist of a GFR housing and a silicone stress cone for field control. This ar- rangement is established and still widely in use. However, if referring to assembly requirements, long-term stability and mode of failure, this sys- tem does not comply with most customer ex- pectations. Nowadays, cable terminations up to UM 170 kV are dry and have solid insulation. The assembly process is easier, there is no liquid in- sulation and therefore failure mode is optimised. By way of disadvantage, they are not self-support- ing and therefore the next evolutionary step is dry type terminations that are self-supporting, ena- bling integration of additional functions.

The discs are connected to the male part of the plug-in system and insulated by a silicone body, which includes field control elements. The head armature (flange) includes a bursting disk for pressure relief and a ‘turnable’ head for re-di- recting the gas in the event of failure, according to IEC 60099-4. The housing is made of glass-fibre reinforced resin and allows great mechanical strength as well as protection of the silicone body against the environment. The silicone body itself is protected and touch-proof. A special arrangement of the earthing path allows for connecting monitor- ing devices or discharge counters, if desired.

Figure 6: Cutaway view of surge arrester Size 4.

Pluggable bushings Conventional bushing are mainly used on trans- formers and these days RIP (resin impregnated paper) types are being more widely used. During assembly of such a conventional bushing, the transformer tank has to be opened and therefore its main insulation, in most cases mineral oil, is exposed to the environment. This process could cause difficulties in view of pollution, humidity and assembly time. With reference to a pluggable system, the transformer is enclosed by a socket, which then offers an interface.This interface allows

Dr. Michael Zerrer is a Senior Manager Development and Ruben Grund is a Senior Portfolio Manager at Pfisterer Kontaktsysteme GmbH.

Figure 7: Evolution of cable terminations.

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round up CABLES + ACCESSORIES

High-performance structured cabling systems

designed for optimised space, allowing easy maintenance and enabling future upgrades. Other features include a fast push-button ex- traction facility and a cable guiding system that ensures neat cable management. LCS³ fibre optic connectors are in- stalled using a small patented splicer that prepares, cleaves and splices the fibre, also offering heat protection. Newly de- signed fibre optic panels and drawers are available in versions from 96 connectors per unit to 144 connectors per unit. These panels have sliding drawers and a fast push-button system for easy maintenance and upgrades. The LCS³ system offers modularity via sliding drawers that enable a mix of fibre optic and copper, while increasing the number of connection points. New rack servers provide greater flex- ibility and optimum efficiency, ensuring optimisation of energy. Installation and maintenance is simplified by the new con- nector locking system and automatic pull- out sliding cassettes. With this system, it is possible to remove connectors without having to disconnect the cords. This system is fully compatible with other Legrand solutions, including new LCS³ enclosures and Power Distribution Units (PDUs), designed for simple set-up and system integration. Wall-mounting cabinets can be fitted anywhere where aesthetic quality is important. Legrand’s new cord locking system, which prevents accidental disconnection, is an important safety

The Legrand Group has made a substan- tial investment in the development of high-performance structured cabling sys- tems that meet the demands of rising data volumes exchanged in buildings, the escalation of networks and the need for higher data speeds, as well as guaranteed continuity of service. New to the range is the LCS³ structured cabling system, developed by Legrand to address the challenges of performance, scalability and efficiency in communica- tion networks for data transmission. The LCS³ copper and fibre optic cabling system, which facilitates easy installation, enables increased data transfer speeds in server rooms, data centres, audio visual systems, workstations and small IT envi- ronments. This system also meets the re- quirements of Local Area Networks (LANs). The copper system offers 25 Gbps and 40 Gbps (Ethernet applications) and the fi- bre optic system, which is the transmission medium that enables a larger bandwidth to be used than copper cables, provides trans- mission speeds of 40 Gbps and 100 Gbps (Ethernet applications). Copper and fibre optic systems are suitable for MTP/MPO high density applications, up to Cat.8. The copper range encompasses con- nectors, patch panels and patch cords and connectors. New tool-less RJ 45 connec- tors ensure a perfect connection within a few seconds, guaranteeing optimum per- formance of the link from the patch panel to the workstation. These components are colour-coded for identification of each cat- egory. (Cat.5e is grey, Cat.6 is blue, Cat.6A is yellow and Cat.8 is aqua). Copper system patch panels are available in flat and angled versions, with up to 48 ports per unit.These patch panels have been

tection accessories enable control of the power supply at the outlets, offering pro- tection against over-voltages. Enquiries: Legrand. Tel. +27 (0) 11 444 7971 or email Legrand.south-africa@legrand.co.za

addition to C13 and C19 sockets. For en- hanced safety and optimum control, specially designed pro-

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round up CABLES + ACCESSORIES

Labelling electronic and electric devices

and can last the lifetime of many electronic and electric devices, even when exposed to more extreme conditions like heat, cold, moisture, abrasion, oils and lubricants, weathering and chemicals. A wide range of UL recognised, reliable label materials that stay attached to any surface are available. Based on application, Brady can determine which label material will offer the desired reliability for any device. Enquiries: Brady Corp.Tel. +27 (0) 11 704 3295 or email emea_request@bradycorp.com

Critical and practical instruction labels on electric and electronic de- vices are important for safety, compliance and ease of use. Brady Corporation offers a complete range of reliable labels that can be designed with the highest flexibility and printed with advanced technologies. Great flexibility More information can be placed on labels for de- vices thanks to extremely accurate printing that allows more special characters, symbols, signs, logos and letters from every alphabet to remain clearly legible in small fonts. This enables increased flexibil- ity in label content and helps companies to better support custom- ers with safety instructions, compliance information and branding by adding a company logo. Brady also offers specialised artwork support to help design labels for maximum impact and clarity. Labels can be offered fully printed and ready to be applied either manually or with a label feeder and existing pick & place machinery in automated production lines. Labels can also be partially pre-print- ed and completed at device production sites with batch codes, production dates or other information using a Brady printer. In au- tomated production this can be done with the BSP61 Print & Apply System, or with the BradyPrinter i7100 Industrial Label Printer and ALF14 Label Feeder. Maximum reliability Brady labels are reliable

Cable seals for for hygienic and wet areas A special challenge is the reliable and permanent sealing of the cable. With this innovative and patented technolo- gy, strain relief and cable seal are strict- ly separated from each other, the strain relief being guaranteed by means of an extremely strong three-way ball clamp that reliably clamps the cable elastic cable seal is po- sitioned right at the ca- ble entry so as to pre- vent any contamination due to penetration of dirt. The highly elastic ma- terial prevents cable sheath deformation and reliably seals even in case of intense cable movement. Simple and safe mounting These connectors also feature the per- fectly tried-and-tested ecolink technol- ogy that allows for reliable and manual M12 connection to the device without use of tools. Enquiries: ifm. Tel. +27 12 450 0400 or email info.za@ifm.com even in case of intense tensile strain. The highly

First-rate multimedia cables Legrand’s extensive range of cable and cable accessories encompasses multimedia ca- bles, which are designed to fit easily into work areas and in spaces where technology-us- ers need access to power and data connections. These cables are compatible with most desktop PC’s, laptops, monitors, scanners and printers, as well as gaming consoles and audio and video equipment. According to Legrand SA, HDMI ® is the most popular audio/visual connection for mod- ern-day consumer electronics. The HDMI signal, which is the digital replacement for analogue video standards, carries digital audio and visual resolutions up to 4 k supporting Ultra HD. DVI products - cables, adapters, extenders and splitters - send high definition 1080p video, from a DVI enabled device to a display. Cat6 patch cables are used for Ethernet connections. In addition, couplers and cable management products are available from Legrand for extending the signal and organising a network. DisplayPorts are designed for connecting high definition digital audio/video devices to displays. The company also offers solutions for both analogue and digital audio/video signal. Legrand multimedia cables also include connectors for audio, video and pc devices and data networks. Audio connectors allow for both analogue and digital signals, whilst video connectors are the perfect solution for adding, duplicating or extending a video device. PC connectors make sure a device stays powered and connected to other devices. These connectors adapt with older technology, ensuring all devices work flawlessly. Data connectors are used for Ethernet and Gigabit networks that require fast bandwidth inten- sive data or for video distribution applications. Legrand’s comprehensive range of products and systems for electrical and digital building infrastructures has been designed for easy installation, high efficiency, optimum safety and enhanced aesthetics -- whether it is an original installation, extension or re- configuration. Enquiries: Legrand.Tel. +27 (0) 11 444 7971 or email Legrand.south-africa@legrand.co.za

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