Report productronica 2015 – “The world’s leading trade fair where the future is the present!”

14/11/2015

On its 40th anniversary, productronica featured plenty of innovations including augmented reality, robotics in electronics manufacturing and the productronica innovation award. Some 38,000 visitors from nearly 80 countries took part in the World’s Leading Trade Fair for Electronics Development and Production. The share of visitors from Asia was up considerably.

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Falk Senger, Managing Director at Messe München, drew a positive conclusion: “During the past four days of the fair, we have experienced the industry’s unbelievable innovative strength. That underscores productronica’s position as an international industry gathering for electronics development and production.” 

productronicaReleases received from exhibitors!

Rainer Kurtz, Chairman of productronica’s Technical Advisory Board, CEO of kurtz ersa and Chairman of the VDMA Electronics, Micro and Nano Technologies (EMINT) Association, sees positive signals for the industry: “There are so many opportunities to drive our business forward. Industry 4.0 is a new market with a great deal of growth potential. And in automotive electronics, all the driver assistance systems are giving electronics production a considerable boost.” The latest figures from a VDMA survey about the business climate verify that. According to studies, growth rates of approximately 15 percent are expected between now and 2018—among other things due to Industry 4.0, the automotive industry, wireless network technologies and mobile communication.

According to a survey by market research institute TNS Infratest, 93 percent of visitors said that productronica met their expectations regarding innovations.

Some 38,000 visitors from nearly 80 countries attended the trade fair in Munich—roughly the same high level as in previous years. According to a survey by market research institute TNS Infratest, visitor satisfaction is very high: 97 percent of visitors gave the fair a rating of good to excellent.

The sharpest increase in attendance was the number of visitors from Asia—and from China, Japan, Malaysia and Singapore in particular. After Germany, the countries with the largest number of visitors were as follows (in this order): Italy, Austria, Switzerland, the Czech Republic, the Russian Federation and Great Britain.

Successful premiere: productronica innovation award
Panel member Prof. Lothar Pfitzner from the Fraunhofer Institute for Integrated Systems and Device Technology IISB, is convinced by the award’s concept: “Given global competition, it is important to further strengthen machine manufacturers, material producers and information technology suppliers in Europe. productronica and the brand new productronica innovation award play an important role for the economy, but also for the scientific sector, and they strengthen horizontal and vertical cooperation. In doing so, they satisfy a key prerequisite for rapid implementation in system development and the user industry.”

Of the more than 70 submissions, awards were presented to the following winners in five cluster categories: Fuji Machine in the PCB & EMS cluster, Rehm Thermal in the SMT cluster, F&K Delvotec in the Semiconductors cluster, Schleuniger in the Cables, Coils & Hybrids cluster, and Asys in the Future Markets cluster.

IT2Industry
IT2Industry, the Exhibition and Open Conference for Intelligent, Digitally Networked Working Environments, was held in conjunction with productronica for the first time ever. The final report for IT2Industry is available in German on the website.

The trade fairs productronica and electronica are held in alternating years, making Munich the most important place for the electronics industry to meet.

• The next electronica takes place from November 8 to 11, 2016, and the next productronica takes place in Munich from November 14 to 17, 2017.


“Were you made for me?” – Choosing the right connector spec.

14/09/2015

Connectors come in all shapes and sizes depending on environment and application. There are literally thousands of options, sometimes for the same job. Inevitably, this can cause a lot of confusion. To make sure you find the best product for every job, there are a few questions you might want to ask yourself before making a purchase. Here Amy Wells, business development manager at Electroustic poses the questions you need to be asking when specifying a connector.

ELE060First things first, size matters. Do you know the physical size of the connector you need, or are you limited in space and height by the job? Hundreds of connectors are used in wire looms; perhaps even thousands if these are part of an automated manufacturing line. In each case, the requisite space needs to be analysed and the correct connector specifications chosen. Sounds simple, but you’d be surprised how often people come a cropper. 

The next question you need to be asking yourself is how many poles the connector needs.

Different applications require connectors with different poles. Future-proofing your choice can be a good idea, especially for a new product. So it’s worth considering whether you should go for more poles than originally required.

Do you know how many mating cycles the connector needs be able to make? Despite what you might think, mating cycles refer to the number of connection or disconnection operations the connector can withstand, while still meeting the specifications for maximum resistance and pull force. Every connector has an expected number of cycles before efficiency is compromised and the connector needs replacing.

This brings us nicely onto the proper protection. Connectors may be susceptible to ingress of foreign materials, such as moisture or dust. Connector protection is provided by the housing and the seal. The IP standard rating system defines the degree of protection provided. The first digit defines the protection against the ingress of dust particles; the second digit defines the protection against the ingress of water. Choosing the right connector for the job is key.

One of the most important factors is knowing what applications and environment a connector will be operating in – we can’t stress that enough. Electromagnetic radiation can interfere with electrical equipment. In applications where electromagnetic radiation is likely to be higher than usual or where operations are critical, connectors need to have electromagnetic fields (EMF) shielding.

Similarly, connectors used in explosive environments must be ATEX certified and components used in military applications need to have Mil-Spec to ensure the highest levels of performance. 

Furthermore, connectors in particularly harsh environments – like those in the oil and gas industry – need to be up for the job at hand. Knowing the minimum and maximum operating temperature is essential for specifying a rugged connector that meets the temperature range set by the application.

It’s not just the connector’s specs you have to be aware of when planning a job. Lead times from manufacturer to supplier can be lengthy, running from anywhere between four to sixteen weeks. It’s no good specifying a part that has a typical 16 week lead time if it will hold up the production process. To combat this potential issue, a good distributor will always hold a substantial amount of stock on the shelf.

Speaking of distributors, they will also be able to advise you on cost effectiveness.  When crafting wire looms, connectors are ordered in bulk, with the resultant savings passed on to the customer. However, if you need just one connector – perhaps if it’s a specialist part – you won’t be quite as lucky. A good working relationship with an experienced distributor can result in alternatives being sourced for a fraction of the price.  

Finally, as any lifestyle magazine will tell you, compatibility is paramount. If you’re retrofitting new connectors to old or simply mating two together in a loom, they need to be intermateable. If not, you risk damage to the system and or data/power loss.


Testing in 2014 – looking forward!

28/02/2014

National Instruments has released its Automated Test Outlook 2014, highlighting the company’s research into the latest test and measurement technologies and methodologies. Engineers and managers can use the report, which examines trends affecting a wide range of industries, to take advantage of the latest strategies and best practices for optimising any test organisation.

ato_2014_4_colThis look into the future explores the following:

Business Strategy: Organisational Proficiency
The talent pool for test engineers is shrinking and test managers must improve organisational proficiency through smarter hiring, better onboarding and greater investment in training to ensure a properly skilled and staffed test organisation.

Architecture: Managed Test Systems
New technologies deliver greater feature sets on test equipment, helping test managers monitor the health of their test systems, lowering test costs and maximising uptime.

Computing: Cloud Computing for Test
Traditional test frameworks limit profitability by not providing the ideal balance of performance and cost or the ability to scale based on actual product demand. Similar to the IT industry, cloud computing applied to automated test can alleviate these growing test concerns.

Software: Scalable Test Software Architectures
Pressure to deliver test systems faster with fewer resources shifts software strategies away from rigid, inflexible solutions in favour of software-based platforms to maximise longevity and scalability across a product’s lifecycle and across new product designs.

I/O: Redefining the Notion of Sensors
The number of sensors in products has significantly increased, challenging test managers to keep up with new technologies and adapt to this growing need. Test managers need agile test solutions they can change as quickly as the sensor-integrated products they test.

Automated Test Outlook 2014 is based on academic and industry research, user forums and surveys, business intelligence and customer advisory board reviews.


The trends that are driving electric drives

19/08/2013
What does the future hold for electric drives in the industrial automation sector? Currently there are three trends which are dictating development – speed and ease of specification, simplified control and maintenance, and machinery safety. Here, Nigel Dawson, Festo GB’s Product Manager for Electric Drives, looks at these trends.

Today’s consumers expect their products, however sophisticated, to be intuitive, readily available, and quick and safe to use. The iPad is a great example; as soon as you take it out of the box, you know how to charge it, switch it on and hey presto you’re up and running in no time at all. What’s more, if you’re a technological Luddite or need help setting it up, there’s simple online support or you can call the hotline for step-by-step assistance.

The future of electric drives: they should be easy to size, easy to order and easy to assmeble – just like the "Optimised Motion Series”

The future of electric drives: they should be easy to size, easy to order and easy to assmeble – just like the “Optimised Motion Series”

This expectation has spread into the industrial world: design engineers and machine builders expect Festo to have products that are easy to specify, for the control technology to be simple, for the maintenance to be straightforward and for the products to adhere to the latest safety legislation.

Trend One
So how can vendors help to reduce the time taken to dimension and select the product? Just as the iPad is quick and easy to select, buy and get up and running, so should electric drives be. Festo has responded to these demands with the introduction of its ‘Optimised Motion Series’, which is a range of electric drives based on those easily accessible and easy to use iPad principles.

The intuitive online configuration tool assists in the specification and selection process and for easier sizing a range of pre-defined and tested combinations with all of the necessary data is available. For easier ordering, a complete drive solution – comprising mechanical system, motor and motor controller – is available with just a single part number. And, for easier assembly, the motor and mechanical system is integrated.

Web brower technology will simplify control technology and handling of electric drives in the future!

Web brower technology will simplify control technology and handling of electric drives in the future!

Second trend
The second trend is for simplified control and maintenance and web browser technology is at work here; it allows the user to source electric drives that are easy to commission, programme and maintain. The demand from the end user is that electric drives have to be intuitive and they don’t want to have to buy specialist programming cables and software.

A standard Ethernet CAT5 cable, which is relatively cheap and readily available, will connect straight into the controller from the laptop and, using a web browser, type in the IP address of the controller, which has its own web page on-board, to commission it (as you would when setting up your own home router). This web-based configuration makes control simple too as it is based on the basic principles of solenoid valve technology. The diagnostic function, accessed via a standard web browser, supports simplified maintenance.

Trend Three
The final trend which is influencing the sector is machinery safety. But, the issue here is that the machinery safety industry is focused on electrically and electronically monitored systems that end at the motor. The question is who is monitoring the mechanics? Here, Festo have developed a unique overall safety concept integrating clamping modules and linear feedback systems onto its popular EGC axis. These mechanical measures, combined with safety functions in the drives and motors and specific electric drive safety controllers allow customers to create fully certified systems for category 4  / PLe safety from a single supplier with full documentation and circuit diagrams.

By understanding these three trends, Festo is opening up new possibilities in industrial automation, making it easier for machine builders and design engineers alike to specify, control and maintain electric drives while ensuring they comply with the latest safety legislation.  Ultimately, machine builders can improve motion control and profit margins, as well as make significant cost savings on integration.


State of control and safety in manufacturing and power generating industries!

29/07/2013

This paper was written by a team at Premier Farnell. Premier Farnell is a distributor of electronics technology.

The power generation industry has gone through many changes in the last 50 years or so and the controls and safety features that were based primarily on the pneumatic controls are now taken over by electronic controls (with its own set of integrated systems resistors, and capacitors) and/or the Digital Control Systems, Furnace safeguard Supervisory Systems (FSSS) and computer controlled systems. The automation systems have improved over the years and now a standard has emerged for the power generating industries. The general improvements in the systems can be enumerated as below. The systems in a boiler control are generally divided in five sections; wiz, drum level controls, steam temperature control, boiler pressure controls, and furnace safeguard Supervisory Systems (FSSS) as also auxiliary interlocks; apart from the boiler water chemistry control. The boiler water chemistry is a separate control not normally associated with other controls and will not be discussed here.

System for drum level controls
Earlier the controls were based on water level in the drum. Sometimes when the steam demand went down the decrease in water level (because of increase of pressure) would tend to supply more water to the drum. This anomaly was rectified by the introduction of a three level control for the boiler drum. In the new system, the difference in the steam flow and the water flow was the main element for control of drum level with correction from drum level adding to the better control. The drum level system can be independent control with its own electronic controls consisting of resisters transistors and capacitors or integrated circuits.

Figure 1: Three element control

Figure 1: Three element control

The system was further refined with pressure and temperature correction from steam parameters. This resulted in better management of drum level. The three element control with the compensation has not undergone any major change over the last 50 years and is now the industry standard.

Figure 2: Three element controls modified

Figure 2: Three element controls modified

Control for boiler pressure
The pressure control has changed from just pressure control to the addition of other parameters like air flow, fuel flow, and the fuel calorific value for pressure control. The online efficiency calculations are also now integrated along with fuel pressure controls. The primary air, secondary air measurements also assists the control of boiler pressure in the system.

Figure 3: Boiler pressure control

Figure 3: Boiler pressure control

Furnace safeguard Supervisory Systems (FSSS)
The FSSS system makes sure that there is no uncontrolled fuel that can cause explosion in the boiler at any stage. The flame is sensed by photo sensors and as long as the flame is available, the supply of fuel is continued to the burners. The absence of flame shuts off all the fuel in the furnace system. Of course the flame sensing is done by two out of three sensors so that at any stage at least two sensors are working and any dependence on a single flame sensor is avoided. Failure of two sensors to see a flame is a signal to close all the fuel supply to the furnace. The fuel can be in solid, liquid or gaseous form. All the fuel in any form will be cut off irrespective of the condition of boiler pressure. The fuel supply cannot be re-started unless the complete purging of fuel is ensured. For ensuring of absence of any fuel in furnace, the furnace is purged with 30% of air flow for 5 minutes and then only the new supply of fuel can be introduced. The purging is done irrespective of the reason of trip. Here also better flame sensors and better

The functions of FSSS are,

  1. Starting of furnace purge after conditions of auxiliary interlocks are satisfied
  2. Permit starting of fuel introduction
  3. Making sure that burners start working only when an auxiliary flame exists
  4. Stopping of all fuel to boiler when flame is extinguished or no longer detected.

FSSS has three units, wiz indicating and operator’s console, relay and logic cabinet with its own electronic circuits of transistors, resistors and capacitors, relays, timers, AC and DC supplies and the fuel trip system.

Figure 4: Typical FSSS panel

Figure 4: Typical FSSS panel

Steam temperature controls
The steam temperature controls ensure that the metals used in construction of the boiler are below the safe limits under which they can operate. The control of steam temperature can be achieved by many means, but the most effective control is achieved by attemperation of steam in the area between the primary and the secondary superheaters. Any increase of temperature can affect the life of parts and may even cause failure of metals of the final superheater.

Figure 5: Steam temperature control

Figure 5: Steam temperature control

Boiler alarm panels that were previously hard wired have started to become much more sophisticated panels. For example, previously changing alarm settings was only possible with the help of an instrument engineer, now the operator of the panel is able to fine tune the alarm setting.

Figure 6: Boiler indicating and alarm panel

Figure 6: Boiler indicating and alarm panel

All these systems were operated as independent systems with no outside communication. These were known as single loop controllers with their own logic. The trip systems operated independently and had no effect on the other entities in a power plant like the turbine, generator or the electrical systems. Additional reliability was introduced with the help of two out of three systems of primary sensing elements. With all of them agreeing on the value of the sensing element, the average value was used for control. When one of them gave a value beyond a permissible error, it was ignored and the other two were used for calculations and an alarm about the third one going out of service was given to the operator. This increased the reliability of the system, something that was not possible with the pneumatic systems.

Other systems like the water management and fire fighting systems could not be integrated with the overall systems, even though operators could get information through hard wired systems. In emergencies, some of these systems were often ignored, resulting in less than ideal ways of handling the emergency.

The next major change was the introduction of a Digital Control System (DCS) and the use of software in the boiler control system. All the above controls were previously independent of one another, but the introduction of DCS and computer software in alarm and emergency handling systems brought the safe shut down of the boiler, turbine and generator. The system of programmable logic controls and the mechanical relays for protection of generators slowly gave rise to the electronic relays in electrical systems and its integration with the DCS.

The architecture of the DCS is local control supervised by additional layers that overlook the entire system. The individual control level of the drum, pressure control, FSSS of boiler, as well as the control of auxiliary interlocks turbine and generator protection, are individual systems which have their own logics and system of alarm generation for decentralized controls, but the information is sent to a higher level where the safety system takes over in emergencies.

In case of emergency situations in individual areas, the system can have its own set of controls over the change in parameters to handle the situation. The safety of the entire system takes precedence over the individual systems and the safe shutdown of the entire system gets activated.

While the individual controls are meant for the control of a single parameter, the alarm system signals the operator about the abnormal condition. The operator can take over the situation and bring the system back to normal. In case the operator is unable to do so and the situation threatens to get out of hand, the shutdown system comes into play. At this stage the operator cannot have any involvement and can only oversee the system shutting down safely.

Overall, the change from individual controls, to dedicated single loop controllers with redundant sensing elements to the DCS formed the line of change to the present method of state of control and safety in manufacturing and power generating industries.


Optimising performance for power plant boilers.

14/05/2012

Steam plant operators are looking for control solutions that will help them to optimize boiler efficiency by reducing fuel consumption while reducing emissions. GE Intelligent Platforms can meet these needs for plants under 300MW with high performance, productized control solutions based on decades of domain expertise in steam cycle generation management that can reduce fuel usage while allowing boilers to run safely and efficiently.

GE’s Steam Cycle control solution is based on a flexible and scalable DCS, Proficy® Process Systems, along with productized pre-packaged advanced combustion control algorithms and strategies for fossil and biomass fuels based on more than 30 years of GE Services experience to achieve significant operational benefits and mitigate risk.

These advanced combustion control algorithms and strategies optimise the combustion process to reduce customers’ fuel usage 3% to 5% which allows them to better meet stringent emissions regulations. In addition, they keep equipment safe and protected by maintaining the water level in the boiler to prevent damage. Because these control algorithms and strategies are pre-engineered, they are capable of reducing system implementation time by 50% to 80%.

“Power plants are running longer with shorter maintenance outages,” said Bill Pezalla, Global Energy Industry Manager for GE Intelligent Platforms. “The advantage of GE Intelligent Platforms’ DCS is that it is an open system that works with any type of boiler and can be implemented during a short maintenance outage leading to the realization of rapid fuel and water savings. These efficiencies need to be factored into the total cost of ownership when purchasing control systems.”

“We’ve extended our Steam Cycle Control solution approach beyond the boiler control by adding boiler and turbine auxiliary equipment control strategies providing an even more comprehensive solution for power plants,” said Craig Thorsland, Steam Cycle Solutions Leader for GE Intelligent Platforms. “Optimally, the overall control solution reduces the need for operator intervention. This stabilizes steam production and frees operators to focus on important plant operations. With stable and consistent operations, we reduce thermal stresses on the boiler and turbine extending their life cycles.”

Safety is a concern for any power producing facility and the Steam Cycle solution addresses that concern with unique drum level control strategies that allow water levels to be properly maintained to avoid boiler failure. “It is critical to keep the water level in the boiler at the proper level,” explained Thorsland. “If it falls too low, the boiler can be damaged, or worse yet, fail with problematic consequences. GE’s unique controls strategies help compensate for varying loads and the resulting increases or decreases in water level.”

Harry Forbes, Senior Analyst at ARC Advisory Group comments: “Economic operation of power plants requires automation systems that respond intelligently to plant disturbances and also drive the plant towards steady operation at the most cost-effective operating points. Recognizing this, GE has integrated strategies for handling various disturbances to the process into its Steam Cycle Solution for industrial boilers and power plants.”

The control system is able to handle conventional fossil fuels as well as the more difficult to control biomass and waste fuels. For biomass fuel plants, the natural variations in the quality and moisture content of the feedstock can results in steam production fluctuations. The system’s BTU combustion compensation control strategies ensure smooth and consistent steam production regardless of these variations. The system facilitates balancing combustion load when grates need to be offline for cleaning and when they are returned to service.

Steam Cycle solutions also give customers the ongoing benefits of reduced fuel use and emissions, lessening the impact of their energy production on the environment. In fact, to comply with emissions regulations and reduce the environmental footprint, combustion factors and emissions levels can easily be captured and analyzed in real-time. The system’s features meet the stringent guidelines of GE’s ecomagination program and therefore it was named an ecomagination product earlier this year.

“Proficy Process Systems with Steam Cycle control is a great solution for fuel savings and operational efficiency,” Thorsland continued. “The combination of decreased installation time with reduced fuel consumption makes this solution a win-win situation for boilers at new facilities and existing plants. The boilers run better, so the turbines run better, so the plants run better.”


Static earthing protection for road tankers

26/11/2010

By Mike O’Brien, Product Manager, Newson Gale.

Introduction

The loading and unloading of road tankers with flammable and combustible products, presents one of the most serious fire and explosion risks for site operations within the hazardous process industries.  A 1967 study conducted by the American Petroleum Institute Identified electrostatic discharges as being responsible for over 60 incidents in road tanker loading operations, demonstrating just how long this potential threat has been acknowledged. The natural presence of static electricity in product transfer operations, combined with its associated ignition hazards, ensures that regulators take static control precautions for road tankers very seriously.

Static electricity and road tanker product transfer operations.

Powders and liquids with low electrical conductivities are the prime sources of static charge generation because their electrical properties do not easily permit the transfer of excess charges. Instead, non-conductive and semi-conductive liquids and powders retain and accumulate charges after they make contact with conductive objects. The most common interface for charging of non-conductive and semi-conductive product is contact with metal plant equipment including pipes, filters, pumps, valves, barrels, IBCs, mixers and agitators. When the electrostatically charged liquid (or powder) is deposited into a container like a barrel, IBC, or road tanker charging of the container will occur if there is nowhere else for the charges to go. In this situation the charges are “static”, accumulate on the surface of the container and set up a potential difference with respect to earth.

Voltage potentials generated on road tanker versus time under normal flow conditions with no static grounding protection in place.

Over a short time period (less than 20 seconds) potentials in excess of 50,000 volts can be induced on a road tanker’s container when it is being filled at normal flow rates with a product that is electrostatically charged. The magnitude of the voltage induced is directly proportional to the quantity of charges making contact with the container.

This voltage represents the ignition source and the potential energy available for discharge via a static spark at voltage levels of 50 kV can, for a typical road tanker, be in excess of 1250 mJ. The vast majority of flammable vapours and combustible dusts can be ignited at these energy levels.

For sparking to occur in road tanker product transfer operations, other conductive objects must come into close proximity with the charged container of the road tanker. Examples of conductive “objects” include the fill pipe entering the opening on the top of the container, fall prevention systems like folding stairs, and drivers or operators working around the road tanker.

The charges on the road tanker’s container attract opposite charges to the surface of the object and rapidly create an electric field between their respective surfaces. It is the strength of this electric field that causes the “breakdown” of the air between the container and the object. When the air is “broken down” a conductive path for the excess charges to rapidly discharge themselves is created, leading to a static spark discharge. If a combustible atmosphere is present in this space, ignition of the atmosphere is very probable. Under ambient conditions an average field strength of 30 kilo-volts is capable of causing the electrical breakdown of air over a spark gap of 10 cm.

Potential ignition energy levels generated with respect to time under normal flow conditions with no static grounding protection in place.

In addition loose conductive items located inside the container could become charged by contact with the liquid and discharge to the container if they are capable of floating on top of the liquid. It is important to carry out regular visual inspections of the container to ensure loose debris is not present inside the road tanker container.

Standards and recommended practice governing the static control of road tanker product transfers.

As outlined earlier, regulators are extremely cautious about the ignition hazards presented by static electricity in road tanker product transfer operations. Three standards, in particular, provide clear guidance on what precautions should be taken. NFPA 77, API RP 2003 and CLCTR: 50404 state that grounding (earthing) of the road tanker should be the first procedure carried out in the transfer process. Grounding effectively creates an electrical circuit that connects the road tanker to the Earth and it is this connection to Earth which prevents static charges accumulating on the road tanker’s container. The reason the charges can transfer from the road tanker is because the Earth has an infinite capacity to absorb and redistribute static charges, with the positive effect of removing the ignition source from a potentially combustible atmosphere.

The electrical resistance of this circuit from the road tanker to the “ground source” (or “grounding  point”) which is in contact with the Earth, is a key performance indicator of the entire grounding circuit’s capacity to provide a secure and safe product transfer operation. NFPA 77 and API RP 2003 state the resistance in a healthy metal circuit should never exceed 10 ohms, therefore the entire grounding circuit between the truck and grounding point should be measured and be equal to, or less than, 10 ohms. If a resistance above 10 ohms is measured this will indicate problems with parts of the grounding circuit including the road tanker connection, the ground point connection or the condition of the conductor cable.

Road tanker grounding systems.

The standards state that a grounding system, which can measure and monitor resistance in the grounding circuit, can be utilised. The system should verify if the ground connection to the road tanker is complete before loading or unloading is initiated. The CLCTR: 50404 standard recommends 10 ohms or 100 ohms for “convenience” in monitoring.

Dedicated road tanker grounding system which continuously monitors the connection to the road tanker and the site's verified grounding point

An additional recommendation in NFPA 77 and API RP 2003 calls for interlocking the feed system (e.g. pump) with the grounding system so that if the grounding system is not connected to the road tanker, product cannot be transferred. This will ensure that product cannot enter or leave the road tanker when the road tanker has no grounding protection in place. In general, interlocked grounding systems will complete the grounding circuit when the driver connects the clamp of the grounding system to the road tanker and the system sees a circuit resistance of 10 ohms or less.

Although the standards recommend a monitored resistance of 10 ohms, there are many grounding systems on the market today that monitor well in excess of this level. While it may be claimed that these systems are capable of dissipating static charges the capacity of a system to monitor at 10 ohms, not only provides an opportunity to demonstrate compliance with internationally recognised recommended practice, it also means that hazardous location operators know the system’s grounding clamp is making a secure and reliable connection to the road tanker every time a product transfer is carried out. Grounding clamps should be designed to penetrate paint coatings, rust and general dirt build up as they are very effective at impeding secure electrical contact with the conductive metal of the road tanker.

Additionally, the grounding system must be capable of detecting minute changes in resistance when the transfer is underway and should not allow a high degree of change in resistance before shutting down the pump or alerting personnel. As soon as a resistance above 10 ohms is present in the grounding circuit, the grounding system should be capable of detecting this change and take control of the feed into the road tanker. Systems that permit resistances higher than 10 ohms have a greater degree of difficulty in detecting changes in the health and condition of the grounding circuit.

The grounding system should also confirm a continuous monitored bonding connection to the ground source as it this connection which is critical to dissipating static charges from the road tanker. As highlighted earlier the ground source can be the gantry structure, ground bus-bars or grounding rods all with a pre-verified low contact resistance with the Earth.

Road Tanker Recognition

Because resistance monitoring systems operate when connected to conductive metal objects, additional features can enhance the protection of drivers, product and equipment.  A “road tanker recognition” feature can be utilised to ensure that drivers can only operate the feed system when the grounding system detects it is connected to a road tanker. A system like the Earth-Rite RTR will analyse the capacitance of the road tanker as part of the grounding circuit. If the capacitance presented is in the normal range for tanks trucks the grounding system will recognise that it has made a positive connection to a road tanker. From the site operator’s perspective, this eliminates the risk of drivers unknowingly connecting the grounding clamp to parts of the truck chassis that are electrically isolated from the truck’s container. This isolation may be due to original design oversight like isolated mud guards or paint coatings insulating conductive parts like truck light enclosures from the chassis. In addition drivers have been known to attach the grounding system’s clamp to the loading rack in order to obtain a permissive state for the feed system to “speed up” the transfer.

So while a permissive state for the feed system can be obtained with a standard resistance based monitoring system it does not necessarily mean the grounding clamp is electrically connected to the road tanker’s container. Specifying a grounding system with a road tanker recognition feature ensures the road tanker is safely grounded before drivers are in a position to begin filling it with product. Once the system has verified it is connected to a road tanker it should then monitor the road tanker’s connection to the grounding point to 10 ohms, or less.

The Ground Source

When a road tanker grounding system is installed it is assumed that the ground source (e.g. buried ground electrode) to which the system is connected has been independently verified as having a low resistance connection to earth. This connection is the foundation for secure and safe transfers and it is incumbent on the site operator to conduct seasonal “Fall of Potential” tests to ensure these ground connections do not deteriorate due to changes in soil composition, soil resistivity or corrosion of the ground electrode.

In Winter, ground temperatures can reduce dramatically and cause an exponential increase in soil resistance levels. For the ground electrode these temperatures can have a significant impact on its contact resistance with the soil potentially impeding the transfer of static charging currents.

Standard grounding systems are not designed to verify this connection, however, the patented Earth-Rite RTR can remove this uncertainty. This system has a unique feature which verifies that it is connected to a grounding point which is capable of safely dissipating static charges to ground. In combination with road tanker recognition capability, this “Static Ground Verification” function ensures that two vital connections in the grounding process are securely made before product is allowed to leave or enter the vehicle.

When both of these connections are confirmed, the system will continuously monitor the resistance of these connections at 10 ohms (or less) for the duration of the transfer process. Should either connection be opened during the transfer, the system will detect this and switch off power to the pump or valve actuators in order to stop the feed of charged liquids into, or out of, the road tanker.

Summary

In accordance with the recommendations of industry groups and fire safety associations, the static grounding of road tankers is a key safety protocol in the loading or unloading of flammable and combustible products.  Grounding ensures static charges are not permitted to accumulate on the road tanker thereby eliminating the risk of the container becoming an ignition source. Additionally, national and international recommended practice advocates the adoption of static grounding parameters that will enhance the safety of the product transfer process including monitoring the grounding circuit to 10 ohms or less and interlocking the product feed system with a dedicated grounding system.

When selecting road tanker grounding systems, specifiers should also consider additional functions that can enhance the safety of the transfer process. Grounding systems which include Road Tanker Recognition and Static Ground connection verification functions provide additional guarantees that a transfer process cannot take place unless the road tanker is connected to the grounding system and the grounding system itself is connected to a verified ground source. These features enhance the secure grounding of the road tanker and enable hazardous area operators demonstrate the highest levels of compliance with NFPA 77, API RP 2003 and CLCTR: 50404.