Electricity + Control 2019

FEATURES: · Control systems + automation · Electrical protection + safety · Cables + accessories · Plant maintenance, test + measurement · Pressure + level measurement + instrumentation

Taking the pulse of your plant with

COMMENT

ON THE COVER

FEATURES: · Control systems+ automation · Electrical protection+ safety · Cables+ accessories · Plantmaintenance, test+measurement · Pressure+ levelmeasurement+ instrumentation

Have we reached the point of inflection?

I mean, in the true sense, as defined in mathematics – calculus. In this case, has the curve moved from some years of being negative, to even a fleeting moment of being positive? It would be nice to be able to answer that question. It would also be very hard to imagine that the curve could travel any further downwards though, wouldn’t it? I find myself reflecting on this after yet another remarkable week for South Africa, and Africa, at the Intel International Science and Engineering Fair (Intel ISEF), this year convened in Phoenix, Arizona. It is the largest competitive science fair on the planet and this year it attracted a re- cord number of participants from around the world – over 1 800. It also attracts over 700 judges from around the world – all profes- sional scientists, engineers and educators. South Africa did well – as we have come to expect. But what has become very evident over the past few years is the increasing suc- cess of other African countries, in particu- lar Zimbabwe, Kenya, Tunisia, Egypt and Nigeria. This bodes well for the youth of the continent – and for the future of the continent. It does remind us of the importance not only of education per se , but specif- ically of science, technology, engineer- ing and mathematics (STEM) education. STEM is becoming the cornerstone of the modern world and it is profoundly encour- aging to see the emergence of a highly skilled, technologically savvy new genera- tion on our continent. I am of the view that this generation will disrupt STEM much like they have be- gun to disrupt other systems – bringing a new creativity to the discourse of science, technology and innovation. I do have a caution, however, and that relates to the general stagnation of Basic

Education in South Africa – a lost opportu- nity if ever there was one. Notwithstand- ing the numerous examples of new think- ing, best-of-breed learning and world-class facilities, it remains deeply concerning that many of our youth simply do not have ade- quate opportunities at school level. I will not pursue this now – as I have done so many times in the past. But if ever one wanted to ensure change, the surest way is through proper education. A very small proportion of all the com- petitors at the Intel ISEF get awards – as it should be. But it is obvious to me how attendance at the event is a life- changing experience for by far the majority of attendees. And I do not mean in terms of the prize money on offer (which is millions of dollars), but in terms of the experience of meeting people who actually take STEM seriously – and not just because they are told to do so. It strikes me that the readers of Electricity+Control would generally fall into this group – people who are not intimidat- ed by science, but rather motivated by it, motivated by seeking out solutions – in fact, driven to identify problems and solve them. Society tends to overlook these rock stars of science. It is brilliant when there are events that celebrate them. After all, were it not for these people, real rock stars would not exist at all… nor would they have the technologies they rely on. To all you problem solvers, I wish you another happy read.

Taking the pulseof yourplantwith

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Endress + Hauser 's flow, level, temperature and analytical instruments are equipped with intelligent Heartbeat Technology. (Read more on page 9).

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CONTENTS

Features

CONTROL SYSTEMS + AUTOMATION 4 The future of collaborative robots Maciej Kuczynski, Omron Industrial Automation

6 Sensor technology in the age of Industry 4.0 Benedikt Rauscher, Pepperl + Fuchs

7 Round UP

ELECTRICAL PROTECTION + SAFETY 12 Lightning and surge protection for hazardous areas DEHN + SÖHNE

16 Understanding the terminology in IEC 61439 Johan Basson, JB Switchgear Solutions

17 Round UP

CABLES + ACCESSORIES 23 Round UP

4

PLANT MAINTENANCE, TEST + MEASUREMENT 26 New technology drives precision machining retrofit Siemens AG

27 Round UP

PRESSURE + LEVEL MEASUREMENT + INSTRUMENTATION 31 Measuring the liquid-liquid interface Magnetrol International 32 Differential pressure measurement in tough conditions Claudia Homberg, VEGA Grieshaber KG

34 Round UP

16

26

Regulars

1 Comment 9 Cover article 37 Engineering the future 39 Cyber security 40 Write @ the back

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The future of collaborative robots

Maciej Kuczynski, Omron Industrial Automation, Johannesburg

Factories worldwide are dealing with manufacturing a high mix of low-volume products to meet customer demands, in addition to shorter product life cycles and labour considerations. Manufacturing companies need to stay flexible in quick line changeovers and layout changes.

In applications where flexibility is key, col- laborative robots with user-friendly software tools and integrated sensory functions are expected to make up an increasing share of all industrial robots. Take Note!

1

C ollaborative robots that can work safely in the same environment as people have an important role in enabling flexible manu- facturing and creating a competitive advantage. A new generation of ‘cobots’ is emerging as the evolution of classical industrial robots in response to the needs of Industry 4.0. In applications where flexibility is key, as opposed to maximum production speed, collaborative robots are now filling the gap in the robotics market with their user-friendly software tools and integrated sen- sory functions, which include machine vision sys- tems, location capabilities and integration with warehouse systems.

Handling heavy lifting Collaborative robots are gaining strength. Although light in weight, the OmronTechmanTM14M robot, for example, can lift goods of up to 14 kg. While compliant with the ISO 10218 safety standard, which describes the interaction of robots and hu- mans, industrial collaborative robots are becoming actual team members in production and logistics environments thanks to their lifting capabilities. This brings innovation to the factory floor through the harmonisation and collaboration of humans and machines. Collaborative robots can be deployed in a range of applications, such as production, testing, quality

With built-in intelligent vision robots can be used in a wide range of manufacturing and material handling processes.

Collaborative robots are designed to work with humans in a cooperative and comple- mentary way.

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control, packaging and palletizing, and intralogistics. They can support people in assembly processes at those stages where precision and repeatability are key. They can, for example, apply adhesives and seals with simultaneous quality control. Due to the repeatability factor, they are also well suited for au- tomating complex quality tests. With the ability to handle heavy lifting, they can be used as palletizers, with proper safety equipment. On the move The new generation of collaborative robots can be integrated easily with mobile robots. Such cooper- ation is made more accessible by the low weight of the latest robots as well as the possibility of building mobile platforms on mobile robots, as in the Omron LD autonomous intelligent vehicle. Col- laborative robots can now be part of a flexible, con- stantly evolving production environment in which the re-deployment of machines, line changeovers and conveyors are needed. Collaborative robots installed on mobile robots can become elements of innovative logistics solu- tions, providing complete sub-assemblies and semi-finished products for assembly stations, and finished products to be placed in stock or quality control stations. Currently, collaborative robots can effectively complement and augment the work done by people in many discrete manufacturing processes. Becoming smart Collaborative robots are just beginning to enable innovation and advance competitiveness in the manufacturing environment. With the advantages of high versatility and the ability to carry out tasks so far performed only by standard robots, all easily configurable by local engineering staff, cobots also offer further benefits. Easier implementation as a result of the reduced need to provide the security measures required by typical robots and incompa- rably greater flexibility of operation are two key fac- tors that support a positive return on investment. It is therefore expected that cooperative and collab- orative robots will constitute an increased share of the total number of industrial robots. The capabilities of machine vision combined with artificial intelligence open up further possibili- ties. A collaborative robot can have a built-in intel- ligent vision system which provides totem pairing, object position, bar code identification, colour dif- ferentiation, and other vision functions. Gestures can be used to guide the robot and the task by hand and to change the degree of freedom of the

hand-guide function easily, according to different conditions. Omron’s interactive table tennis robot, For- pheus, demonstrates just some of the possibilities of artificial intelligence (AI) combined with collabo- rative robots. Forpheus demonstrates human ma- chine collaboration by combining vision with robot- ics and artificial intelligence on the machine level. It can play an interactive game, identify ping-pong balls in a 3D space in the same way as the human vision system does, as well as evaluate the player and judge their ability level. Its high-speed robotic arm moves in response to its AI controller; it can even predict smashes. Combining artificial intelligence on the machine level with vision systems and mobile collaborative robots opens up even more exciting possibilities for new industrial applications. For the future Omron andTechman Robot Inc., a leading company for collaborative arm robots that work together with people, recently signed an agreement to form a strategic alliance in the area of collaborative robots. Omron and Techman will provide collaborative robots that can be used for various applications such as electronics assembly, product testing and inspection.The aim is to develop and deliver robots that will enable flexible manufacturing and increase the productivity and quality of production lines for customers in the automotive and electronics industries, as well as material handling operations across a range of manufacturing industries, and to realise an innovative manufacturing environment where humans and machines work in harmony.

The aim is to develop and

deliver robots that will enable flexible manufacturing and increase the productivity and quality of production lines in the automotive and electronics industries, as well as material handling operations across manufacturing.

About the author Maciej Kuczynski has over 15 years of engineering and business experience in industry and infrastructure operational

technology. He has a PhD degree in Machine Construction and Opera- tions from the Warsaw University of Technology. He specialises in projects related to business development and IIoT/OT in the area of safety & security. At Omron Maciej is responsible for managing regional marketing activities.

For more information: Omron Industrial Automation Tel: +27 (0)11 579 2600, email: info.sa@eu.omron.com or visit: www.industrial.omron.co.za

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Sensor technology in the age of Industry 4.0 Integrating information from sensor to data platform Sensors are already delivering a lot more than just data. Additional data can be transferred onto platforms using the correct interfaces and protocols. By using appropriate interfaces, communication components and semantic agreements, all sensor data can be made available in cloud systems or local data platforms so it can be processed even without detailed knowledge of the transmission technology, thus abstracting the communication channel. Benedikt Rauscher, Leader of Global Industry 4.0 Projects, Pepperl + Fuchs

1. Sensors are in effect the sensory organs of machines and plants and are keystones in Industry 4.0 scenarios. Take Note! 1

S ensors convert physical effects into elec- trical values and make them available for further processing. They are in effect the sensory organs of machines and plants and are keystones in Industry 4.0 scenarios. In addition to pure data, sensors deliver a large amount of valuable data about their identity or their condition, for example. It is also possible to use parameter sets to adapt the sensors perfectly to different applications. Bidirectional interfaces and protocols are need- ed to transfer these parameters to the sensors and receive data from them. The interfaces and protocols must follow the applicable standards strictly so that products from different manufac- turers can be used without any issues. IO-Link has established itself as the interface of choice for ‘the final centimetres’ in sensor technology; Ethernet-based technologies such as EtherCAT, PROFINET and EtherNet/IP, among others, are also used for more complex units. Pepperl+Fuchs uses the trademarked term Sensorik4.0 ® for its portfolio of products that have been designed in line with this concept and equipped accordingly.

When sensor data is being evaluated, applica- tions for data processing in closed control loops have to be considered separately. There are often tough real-time demands in such scenarios, mean- ing that appropriate PLC hardware needs to be used in conjunction with communication channels that perform efficiently. The processing of all other data supplied by sensors is generally not time-sensitive, but this data must be recorded, stored and processed over longer periods of time. In addition to those for signal transmission, par- allel data paths to data platforms are constructed. So-called edge gateways are used for this pur- pose. Edge gateways communicate with sensors and actuators via control modules and PLCs while also establishing connections to data platforms. This is done using protocols that support publish/ subscribe mechanisms such as MQTT, AMQP, or OPC/UA with publish/subscribe extension. A data platform can be operated on a plant oper- ator's local network or as an online cloud solution. These platforms feature databases for structured storage of sensor data and provide interfaces that allow various applications to access the data.

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along with the devices. Depending on the tech- nology, different formats are used (EDDL, GSD, GSDML, IODD). The challenge in connecting field devices is loading and interpreting the device descriptions and making the data supplied from the field devices accessible in the data platform using a generic set of semantics. Ideally, data from field devices can then be accessed without needing to know the communication technology that has been used. Pepperl+Fuchs has worked with Neoception and CodeWrights, to develop a solution for process engineering field devices.

Sensor data is transmitted by accessing the platforms via an application programming interface (API), which is unique to every system. To connect an edge gateway, the gateway software must use this platform's API. Pepperl+Fuchs has created a spin-off company for such software services to give its customers flexibility in choosing a data platform. Neoception combines expertise in sensors and IT know-how and provides links (known as connec- tors) to all cloud systems available on the market. There is a range of different protocols for com- munication on the sensor/actuator level, but no uniform set of semantics. For each type of field device, appropriate commands must be generated according to specific rules and the answers must be interpreted in accordance with these rules. The specific properties of the field devices can be found in the description files (‘Device Description’, DD), which are supplied by the manufacturers

Sensors deliver data on industrial processes as well as about their identity and condition; parameter sets can be adapted to different applications.

For more information contact Pepperl+Fuchs, email: info@pepperl-fuchs.com, or visit: www.pepperl-fuchs.com

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CONTROL SYSTEMS + AUTOMATION

A growing online engineering community

- an advanced 3D CAD tool based on direct mechanical model- ling techniques - a fully specified electrical CAD package for the design of con- trol panel, machinery and electrical systems - a library of schematic symbols and PCB footprints, which are - the DesignSpark Toolbox app for engineers, and other tools. DesignSpark further provides a platform for members to share their projects and opinions and connect with other engineers and students. Last year, RS Components launched its Africa website which is geared to meet the requirements of a growing mar- ket with demand from various industries such as manufac- turing, mining, automotive, utilities, electronics and industrial IoT. The new website enables customers to receive their prod- ucts more quickly, delivery costs are cheaper and customers can pay online. This opens the door for more markets in Sub- compatible for leading PCB software packages - 3D models available to use in CAD designs

RS Components (RS), the trading brand of Electrocomponents plc, a global multi-channel provider of industrial and electronic products and solutions, recently announced that its DesignSpark online en- gineering community has grown to more than 750 000 members. DesignSpark was launched in 2010 to provide design engineers and students around the globe with free tools, resources and con- tent to help them remove barriers, save time and turn their ideas into reality. Mike Bray, Vice President of DesignSpark, said, “We would like to say a huge thank you to every single member of the DesignSpark community. There is a great feeling of togetherness within the community and it is great to see how engineers support each other to achieve amazing things with the help of our tools and resources. “Since day one, RS has sought to give something back to the electronics industry through DesignSpark, by providing free pro- fessional tools and resources for engineers. We are proud to see the continuing growth of the community and are committed to further enhancing our platform for the growing user base.” During the nine years since it launched DesignSpark, RS has continued to improve the functionality and range of resources available through the online ecosystem. This has resulted in an increase in new members; more than 35% of DesignSpark’s cur- rent membership joined in the past two years. Registering on DesignSpark is free of charge and all members gain access to: - a professional-grade schematic-capture and PCB design soft- ware package

Saharan Africa to access prod- ucts through the dedicated e-commerce platform. Enquiries: RS Components. Tel: +27 (0)11 691 9300, or visit: www.rsonline.africa DesignSpark offers members an interactive platform to share projects and ideas.

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Intelligent process automation in freight industry

Network will help our customers optimise their logistics and put their customers at the heart of their digital supply chains.” SAP Logistics Business Network, built on SAP Cloud Platform and the SAP HANA ® business data platform, expands transport management to enable shippers, freight forwarders, carriers and other logis- tics partners to on-board, collaborate, ex- change logistics information and share in- sights. With this industry-first Uber Freight integration, shippers and carriers can work together. Shippers can select from a broad- er carrier base and perform real-time pric- ing of shipments, while gaining improved usage and efficiency. Bill Driegert, Senior Director, Uber Freight, said, “For the world’s biggest ship- pers, an efficient, digitalised supply chain is critical to their business success. Uber Freight is partnering with SAP to bring shippers and carriers together at the level

where freight decisions are being made. This innovative tech-forward approach to freight means shippers can spend less time sourcing quotes and capacity and more time getting goods to market.” SAP and Uber Freight will work to con- nect both sides of the freight marketplace, increasing visibility and transparency for all players. The aim is to support easier and faster decision-making based on real-time pricing for shippers and carriers, empow- ering organisations to maximise daily work time and make more informed decisions about their operations. A networked approach can also help minimise unloaded mileage, reducing costs and carbon footprint. Uber Freight provides a highly available, dense carrier network that shippers can access directly through SAP Logistics Business Network. Shippers can access capacity by unlocking a larger ecosystem of drivers, and carriers

SAP SE and Uber Freight have announced a partnership to advance the freight industry through intelligent process automation and better access to a network of connected and reliable drivers. The integration of Uber Freight into SAP ® Logistics Business Network will enable customers to access transport rates from Uber’s digitally activated carrier network, to source real-time quotes and guaranteed freight capacity, simplifying load management and execution. “Finding and booking freight can be the most expensive and often the most com- plex piece of the supply chain,” said Hala Zeine, President, SAP Digital Supply Chain. “This combined solution will remove road- blocks and offers a simpler, more automat- ed approach that streamlines operations, delivers tangible cost savings and creates a better customer experience. Adding Uber Freight to our SAP Logistics Business

and drivers gain the ability to see and choose loads that fit their businesses and sched- ules. This improves usage, reduces time to plan and min- imises costs at all levels of shipping operations. Current entrenched inef- ficiencies in the supply chain can lead to waste. Every year, underused trucks reported- ly generate 200 million tons of emissions. By leveraging technology to change the freight planning process and better use capacity, the in- dustry can make a positive impact toward environmental sustainability. Enquiries: www.sap.com or www.uberfreight.com

Exhibiting at Africa Automation Fair 2019 Phambili Interface – a proudly Bidvest company and the exclusive distributor forWeidmüller's connectivity and interface products in south- ern Africa – will be exhibiting at the Africa Automation Fair (AAF), which is taking place in Johannesburg from 4 to 6 June 2019. A highlight at the Phambili stand at AAF will beWeidmüller's perfectly coordinated IIoT u-mation portfolio. The combination of modular automation hardware, innovative engineering tools, sophisticated digitalisation solutions and intelligent machine learning modes, enables the connection of all levels of a process – from the sensor to the cloud. Enquiries: Peter Mc Donald at Phambili Interface.Tel: +27 (0)11 452 1930, email: pmcdonald@weidmuller.co.za www.weidmuller.co.za

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COVER ARTICLE

FEATURES: · Control systems+ automation · Electrical protection+ safety · Cables+ accessories · Plantmaintenance, test+measurement · Pressure+ levelmeasurement+ instrumentation

The heartbeat of plant processes – Self-diagnostics and predictive maintenance

Taking the pulse of your plantwith

EC June 2019 coverFriday.indd 1

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I magine a production process where devices can diagnose themselves: they would realise when something is wrong or unusual and send an alarm. When, for example, excessive build- up occurs in silos and tanks, devices with this capability would signal the need to clean a process. It’s as if your field measurement device has a heartbeat: it will react like an additional member of your workforce with specialist knowledge to steer the process in an effective way so that you avoid costly downtime. You just run the plant and processes and do not have to spend time checking how the instruments are working. The devices would tell you directly if a problem occurs. Processes that can take their own pulse are already a reality with Endress+Hauser's Heartbeat Technology. Since 2012, self-diagnostics has been standard in several Endress+Hauser flow devices and the portfolio has now been expanded to include level, temperature and analytical devices. Instruments with Heartbeat Technology enable permanent process diagnostics and extensive in- situ diagnostic functions. Processes are no longer interrupted if verification is needed; it happens

directly at the measuring point without any dismantling. The advantages of instruments with self- diagnostics are evident: plants run more cost- effectively, safely and without interruptions. You are always in control of your measuring point and verification efforts are significantly reduced with documented in-situ verification. A simple, predefined procedure guides the maintenance technician through the verification steps and the verification results are documented in an unambiguous way. The safety integrity level (SIL) test, in line with the safety manual and documentation, saves time and reduces costs too. An automatically generated verification protocol supports the evidence required by regulations, laws or plant standards. The data acquired through self-diagnostics facilitates trend recognition for predictive maintenance. A combination of instrument and process parameters provides all the important information for the next steps in maintenance or targeted process optimisation. It is a prerequisite to finding the right strategy for predictivemaintenance.

For more information contact: +27 (0)11 262 8000 or email: info@za.endress.com or visit: www.endress.com

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Real-time machine learning for control systems

The models to be learned are trained in an ML framework, such as MATLAB ® or TensorFlow, and then imported into the TwinCAT runtime via the Open Neural Network Exchange Format (ONNX), a standardised data exchange format used to describe trained models. The TwinCAT runtime incorporates the following new functions for this purpose: the TwinCAT 3 Machine Learning Inference Engine for classic ML algorithms, such as support vec- tor machine (SVM) and principal component analysis (PCA); and theTwinCAT 3 Neural Network Inference Engine for deep learning and neural networks, such as multilayer perceptrons (MLPs) and convolutional neural networks (CNNs). Inference, that is, the execution of a trained ML model, can be performed directly in real-time with aTwinCATTcCOM object. With smaller networks, system response times of less than 100 µs cor- responding to aTwinCAT cycle time of 50 µs are supported. Models can be called via PLC, C/C++TcCOM interfaces or a cyclical task. Through seamless integration with the control technology, the multicore support provided by TwinCAT 3 is also available for ma- chine learning applications.This means, for instance, that different task contexts can access a particular TwinCAT 3 Inference Engine

Beckhoff offers a machine learning (ML) solution that is seam- lessly integrated intoTwinCAT 3 software. Building on established standards, TwinCAT 3 Machine Learning brings to ML applications the advantages of system openness familiar from PC-based con- trol. In addition, the TwinCAT solution supports machine learning in real-time, allowing it to handle demanding tasks like motion control. These capabilities provide machine builders and manufac- turers with an optimum foundation for machine performance – through prescriptive maintenance, process self-optimisation and autonomous detection of process anomalies, for example. The fundamental concept of machine learning – rather than following the classical engineering route of designing solutions for specific tasks and then turning these solutions into algorithms – is to learn the algorithms from exemplary process data. With this approach, powerful ML models can be trained and then used to deliver better-performing solutions. In automation technology this opens up new possibilities and optimisation potential in many areas, including predictive maintenance and process control, anomaly detection, collaborative robotics, automated quality con- trol and machine optimisation.

without restricting each other. All the fieldbus interfaces and data available in TwinCAT can be accessed as well. This allows ML solutions to use immense amounts of data, for example, for complex sensor data merging, and it also means that real-time interfaces to actuators are available to enable, among other things, optimal control.

Enquiries: Beckhoff Automation. Tel: +27 (0)11 795 2898, email: press@beckhoff.co.za

With TwinCAT 3 software, automation experts can tap into new machine learning and deep learning possibilities within a familiar engineering environment.

Smart sensor in flat pack design The new compact rectangular housing of the IQ2000 sensor makes it ideal to fit the limited space found in conveyor technology and factory automation. The flush installation of the sensor facilitates mounting and prevents mechanical damage. Together with high impact- and vibration-resistance and the capacity to withstand a wide range of temperatures, this ensures the sensor’s long life. To solve demanding position detection tasks, the IQ2000 continuously provides the dis- tance value via IO-Link. Two switch points can be set to the nearest millimetre using IO-Link and the sensor offers various configuration options, such as NO/NC or PNP/NPN, which reduce storage costs for different sensor types. Visit ifm electronic ZA at the Africa Automation Fair in Johannesburg, 4 to 6 June 2019. Enquiries: ifm electronic ZA.Tel: +27 (0)12 450 0400, email: info.za@ifm.com

The IQ2000 sensor with compact rectangular housing to fit limited space in automation installations.

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Continuing innovation sees patents rising

This team has full responsibility for handling all patent filings from the group companies located in the US, plus up to 80% of the overseas filings. Under the banner ‘Innovation – what makes us human’, Matthias Altendorf, CEO of the Endress+Hauser Group, as well as other members of the executive board, welcomed more than 300 guests to the annual Innovators’ Meeting. Employees involved in patent filings presented their innovations during the company’s traditional get-together. Exceptional innovations were recognised with special awards. Endress+Hauser is a leader in measurement instrumentation, services and solutions for industrial process engineering. Managed and coordinated by a holding company in Reinach, Switzerland, the group operates globally with dedicated sales centres and a strong network of partners. It provides sensors, instruments, systems and services for level, flow, pressure and temperature measurement as well as analytics and data acquisition. The company supports customers with automation engineering, logistics and IT services and solutions. It works closely with a broad spectrum of industries, from the chemical and petrochemical industries to food & beverage, oil & gas, water & wastewater, power & energy, renewable energies, and pulp & paper industries, among others. Enquiries: www.endress.com

The Endress+Hauser Group filed 287 patents in 2018, a new record that was reported during the group’s annual Innovators’ Meeting held late March this year in Saint-Louis, France. Endress+Hauser owns nearly 7 800 active intellectual property rights worldwide. Angelika Andres, Corporate Director, Intellectual Property Rights at Endress+Hauser, noted: “This year we once again achieved a record number of innovations, both in the number of patent filings and the number of approved patents.” While the 309 invention disclosures are a sign of the company’s ongoing innovation capability, the 537 granted patent applications also represent an all-time high. About one third of the patent filings are related to the Industrial Internet of Things, digital communications and instrument diagnostics. Under the motto ‘#empowerthefield’, in 2018 Endress+Hauser, best known as a measurement engineering specialist, began to bundle its digital activities with a focus on Heartbeat Technology as well as the recently introduced Netilion IIoT ecosystem. Each invention undergoes a multistage internal evaluation process before submission to the patent office, usually within four months. To handle the stream of innovations, in 2016 an internal patent department was created in the US, one of the group’s most important markets. Four specialists at the Greenwood Indiana location are responsible for protecting the technical innovations.

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Lightning and surge protection for hazardous areas

When producing, processing, storing and transporting flammable substances (such as fuel, alcohol, liquid gas, explosive dusts) in chemical and petrochemical industrial plants, potentially explosive atmospheres often occur and it becomes imperative to avoid all sources of ignition which may cause an explosion.

Take Note!

1. A conceptual approach, aligned with the relevant safety regulations, is es- sential to providing effec- tive lightning and surge protection for electrical and electronic installations in hazardous areas. The IEC 62305 standard describes different light- ning protection zones that require appropriate levels of protection. 1 2

T he relevant safety regulations describe the risk for such plants posed by atmospheric discharges (lightning strikes). In this context, it is important to note that there is a risk of fire and explosion resulting from direct or indirect lightning discharge since in some cases plants are widely distributed. To ensure continuous plant availability and safety, a conceptual procedure is required to protect parts of electrical and electronic installations of the plant from lightning currents and surges. Protection concept Intrinsically safe measuring circuits are frequently used in potentially explosive atmospheres. Figure 1 shows the general design and lightning protection zones of such a system. As maximum system availability is required and numerous safety requirements must be observed in hazardous areas, specific areas have been divided into lightning protection zone 1 (LPZ 1) and lightning protection zone 2 (LPZ 2):

- Controller unit in the control room (LPZ 2) - Temperature transmitter on the tank (LPZ 1) - Interior of the tank (LPZ 1) According to the lightning protection zone concept as per IEC 62305-4, adequate surge protective devices, as described below, must be provided for all lines at the boundaries of the lightning protection zones. External lightning protection system The external lightning protection system includes all those systems installed outside or inside the structure to be protected which intercept and discharge the lightning current to the earth- termination system. A lightning protection system for potentially explosive atmospheres is typically designed according to class of LPS II. Another class of LPS may be justified in individual cases, in case of special conditions (legal requirements) or as a result of a risk analysis. The requirements described below are based on class of LPS II. Air-termination systems In potentially explosive atmospheres, air- termination systems must be installed at least according to class of LPS II ( Table 1 ). To determine the relevant points of strike, the recommendation is to use the rolling sphere method with a minimum radius according to class of LPS II. However, in case of a lightning strike to the air-termination system, sparking may occur at the point of strike. To prevent ignition sparks, the air-termination systems should be installed outside Ex zones. Existing components, such as metallic roof

Table 1: Arrangement of air-termination systems according to the class of LPS.

α ° 80 70 60 50 40 30 20 10 0

I

II

III

IV

0 2

10

20

30

40

50

60

h [m]

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metal container with a sufficient material thickness

air-termination system

ventilation

building shield, e.g. steel reinforcement

line to the remote potential

intermeshed equipotential bonding system

Figure 1: Basic division of an installation into lightning protection zones (LPZs).

inside the structure to be protected, dangerous proximities may occur between the parts of the external lightning protection system and metal as well as electrical installations inside the building. Since in practice the lightning current splits between the individual down conductors, depending on the impedances, the separation distance must be calculated separately for the relevant building / installation as per IEC 62305-3. Shielding of buildings Another measure of the lightning protection zone concept is shielding buildings. Metal facades and reinforcements of walls, floors and ceilings on or in the building are, as far as practicable, combined to form shielding cages ( Figure 2 ). Electrically interconnecting these built-in metal components of the building or installation to be protected, to form closed shielding cages, considerably reduces the magnetic field. It can be decreased easily by a factor of 10 to 300 and an infrastructure for EMC protection established at low cost. When retrofitting existing installations, the room shielding must be adapted to the EMC requirements, by means of reinforcement mats, for example. Surge protection in hazardous areas The lightning protection and Ex zones are already harmonised at the design stage. This means that the requirements for the use of surge protective devices both in hazardous areas and at the boundaries of lightning protection zones must be fulfilled. The place of installation of the surge arrester is exactly defined: the transition from LPZ 0 B to LPZ 1. This prevents dangerous surges from entering Ex zone 0 or 20 as the interference has already been discharged. The availability of the temperature transmitter, which is important for the

structures, metal pipes and containers can also be used as air-termination systems if they have a minimum material thickness of 5 mm according to Annex D 5.5.2 of the IEC 62305-3 standard and the temperature rise and reduction of material at the point of strike do not present additional risks (such as reduction of the wall thickness of pressure containers, or high surface temperature at the point of strike) ( Figure 1 ). Down conductors Down conductors are electrically conductive connections between the air-termination system and the earth-termination system. To prevent damage when conducting the lightning current to the earth-termination system, the down conductors must be arranged in such a way that from the point of strike to earth: - there are several parallel current paths (systems in hazardous areas: one down conductor for every 10 m of the perimeter of the outer roof edges, but, at least two), - the length of the current paths is as short as possible, - connection to the equipotential bonding system is established wherever necessary. An equipotential bonding system at ground level at intervals of 20 m has proven its worth. Reinforcements of concrete buildings may also be used as down conductors if they are permanently interconnected in such a way that they can carry lightning currents. Separation distance If there are insufficient separation distances between the air-termination system or down conductor and metal and electrical installations

Using the lightning protection zone concept in the design and

installation of chemical or petrochemical

plants, the risks of sparking in case of direct lightning strike or discharge of conducted interference energies must be safely minimised at an economically acceptable cost.

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A number of other selection criteria also apply for surge protective devices in intrinsically safe measuring circuits. These include: - Appropriate insulation strength of equipment. - The type of protection required – whether for Category ia, ib, or ic. - Permissible values for L 0 and C 0 . Before an intrinsically safe measuring circuit can be put into operation it must be proven to be intrinsically safe. The power supply unit, the transmitter, the cables and the surge protective devices must fulfil the conditions of intrinsic safety. - Maximum values for voltage U i and current I i . - Coordination of surge protective devices with terminal equipment. Intermeshed earth-termination system In the past, separate earth-termination systems were often used: the lightning protection and protective earthing were separate from the functional earthing. This proved to be unfavourable and even dangerous. In case of a lightning strike, voltage differences up to some 100 kV can occur, which may lead to the destruction of electronic components, personal injury and explosions in potentially explosive atmospheres due to sparking. Therefore, it is advisable to install a separate earth-termination system for every building or part of an installation and to intermesh them. This intermeshing ( Figure 4 ) reduces potential differences between the buildings / parts of the installation and thus the conduction of partial lightning currents. The closer the mesh of the earth-termination system, the lower the potential

process, is considerably increased. In addition, the requirements of IEC 60079-11, IEC 60079-14 and IEC 60079-25 must be observed ( Figure 3 ): - Use of surge protective devices with a minimum discharge capacity of 10 impulses of 10 kA each without damaging the equipment or interfering with the surge protective effect - Installation of the surge protective device in a shielded metallic enclosure and earthing by means of a copper earthing conductor with a cross-section of at least 4 mm 2 - Installation of the lines between the arrester and the equipment in a metal pipe earthed on both ends, or use of shielded lines with a maximum length of 1 m. According to the definition in the protection concept, the controller unit in the control room is defined as LPZ 2. A surge protective device is also provided at the transition from LPZ 0 B to LPZ 1 for the intrinsically safe measuring line from the temperature transmitter. This surge protective device at the other end of the field line which extends beyond the building must have the same discharge capacity as the surge protective device installed on the tank. Downstream of the surge protective device, the intrinsically safe line is led via an isolating amplifier. From there, the shielded line to the controller unit is routed in LPZ 2. The cable shield is connected on both ends, therefore no surge protective device is required at the transition from LPZ 1 to LPZ 2 as the electromagnetic residual interference to be expected is significantly attenuated by the cable shield earthed on both ends.

conventional lightning protection

shielded building

non-hazardous area

w

w

d r

direct lightning strike

d w

d r

control room

d w

BLITZDUCTOR XT BXT ML4 ... EX + BXT BAS EX

Ex(i) isolator

nearby lightning strike

BXTML4BD EX 24 BLITZDUCTOR

1’ 3’

2’ 4’

2 4

1 3

protected

min. 4 mm 2

s a

s a

Figure 2: Shielding of structures by using existing components of the building.

Figure 3: Surge protective devices in an intrinsically safe

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differences between the buildings / parts of the installation in case of a lightning strike. Mesh sizes of 20 x 20 m (or 10 x 10 m recommended in potentially explosive atmospheres and when using electronic systems) have proven to be economically feasible.When selecting the earthing material, it is important to ensure that the buried pipes do not corrode. Equipotential bonding Consistent equipotential bonding must be established in all potentially explosive atmospheres to prevent potential differences between different and extraneous conductive parts. Building columns and structural parts, pipes, containers, and similar, must be integrated into the equipotential bonding system so that a voltage difference is not to be expected even under fault conditions. The connections of the equipotential bonding conductors must be secured so they cannot work loose. According to IEC 60079-14, supplementary equipotential bonding is required and must be properly established, installed and tested in line with the IEC 60364-4-41 and IEC 60364-5-54 standards. When using surge protective devices, the cross-section of the copper earthing conductor for equipotential bonding must be at least 4 mm 2 . Lightning equipotential bonding outside the hazardous area The use of surge protective devices in low-voltage installations and measuring and control systems outside the hazardous area (such as in the control room) does not differ from other applications. In this context, surge protective devices for lines

from LPZ 0 A to LPZ 1 must have a lightning current discharge capacity which is described by the 10/350 µs test wave form. Surge protective devices of different requirement classes must be coordinated with one another. This can be ensured by creating a protective chain of surge arresters. Shield treatment in intrinsically safe measuring circuits The treatment of the cable shield is an important measure to prevent electromagnetic interference. In this regard, the effects of electromagnetic fields must be reduced to an acceptable level to prevent ignition.This is only possible if the shield is earthed on both cable ends. Summary The risk posed to chemical and petrochemical plants due to a lightning discharge and the resulting electromagnetic interference is described in the relevant standards. When using the lightning protection zone concept for designing and installing such plants, the risks of sparking in case of a direct lightning strike or discharge of conducted interference energies must be safely minimised at an economically acceptable cost. The surge arresters used must fulfil explosion protection requirements, ensure coordination with terminal equipment and meet the requirements resulting from the operating parameters of the measuring and control circuits.

Acknowledgements to DEHN + SÖHNE for the information provided.

The following standards are to be ob- served for the earth-termination system: DIN 18014 Foundation earth electrode (German), IEC 62305-3 (EN 62305-3)

hazardous area

and DIN VDE 0151 (German) Material and minimum dimen-

sions of earth electrodes with respect to corrosion

DEHNpipe DPI MD EX 24 M2

FISCO

Ex zone 0

Ex zone 1,2

easuring circuit.

Figure 4: Example of an intermeshed earth-termination system.

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The IEC 61439 series of standards is applicable to low voltage switch- gear and controlgear assemblies. In this short series of tutorials, Johan Basson looks at some of the terminologies and explains them so the reader may gain better understanding of their meaning. Extracts from the standard itself are used extensively. This third tutorial focuses on the topic of the ‘rated diversity factor (RDF)’ in electrical switchgear and controlgear assemblies. Understanding the terminology in IEC 61439 Johan Basson, Managing Director - JB Switchgear Solutions

An installation showing functional units within an assembly.

I n general all circuits within an assembly are in- dividually capable of carrying their rated current continuously but, the current carrying capacity of any circuit may be influenced by adjacent cir- cuits. Thermal interaction can result in heat being imported from, or exported to, circuits close by. Cooling air available to a circuit may be at a tem- perature well above the ambient temperature due to the influence of other circuits. In practice, not all circuits within an assembly are normally required to carry rated current con- tinuously and simultaneously. Within a typical ap- plication the type and nature of loads differ appre- ciably. Some circuits will be rated on the basis of inrush currents and intermittent or short duration loads. A number of circuits may be heavily loaded while others are lightly loaded or switched off. To provide assemblies in which all circuits can be operated at rated current continuously is there- fore unnecessary and would incur an inefficient VALUES OF RATED DIVERSITY FACTOR Number of main circuits Rated diversity factor 2 and 3 0,9 4 and 5 0,8 6 to 9 inclusive 0,7 10 and above 0,6 Table 1.

use of materials and resources. The standard rec- ognises the practical requirements of assemblies by assigning a rated diversity factor – as defined in IEC 61439-1 chapter 3. 8. 11. In stating a rated diversity factor, the assembly manufacturer is specifying the ‘average’ loading conditions for which the assembly is designed. The rated diversity factor confirms the per unit value of rated current to which all the outgoing circuits, or a group of outgoing circuits, within the assembly, can be continuously and simultaneously loaded. In assemblies where the total of the rated currents of the outgoing circuits operating at rated diversity fac- tor exceeds the capacity of the incoming circuit, the diversity factor applies to any combination of outgo- ing circuits used to distribute the incoming current. Rated diversity factor (RDF) The rated diversity factor is the per unit value of the rated current, assigned by the assembly manu- Notes 1.The assumed loading of the outgoing circuits can be a steady continuous current or the thermal equivalent of a varying current. The rated diversity factor is applicable with the assembly operating at rated current. 2. The rated diversity factor recognises that multiple func- tional units are in practice not fully loaded simultane- ously or are intermittently loaded.

1. In general all circuits with- in an assembly are individ- ually capable of carrying their rated current con- tinuously but, in practice, not all circuits within an assembly would normally be required to carry their rated current continuously and simultaneously. Take Note! 1

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