Features

Rockwell Automation has hosted the 16th annual Automation Fair event. This year's event showcased the ways manufacturers use industrial automation technology and services from Rockwell Automation and its partners to enable innovation.

As one of the largest free educational forums for manufacturing technology, Automation Fair and Manufacturing Perspectives – the international media day before the main event – provide a place to hear the latest success stories from manufacturers and hear from those leading development in manufacturing technology. Manufacturing Perspectives allowed more than 80 editors from 22 nations access to manufacturing experts, global trade leaders and Rockwell Automation’s own customers to share best practices, explore technologies and discuss key issues, the main theme of the day ‘ Automation Enables Innovation’. Attracting over 10,000 visitors over two days, the event is unlike anything seen in this country, and raised many important issues surrounding the future of manufacturing globally.
In October 2007, Bob Ruff was appointed senior vice president of the Control Products & Solutions segment reporting directly to Keith Nosbusch, chairman and CEO.. Ruff was previously senior vice president, Americas Sales.

Ruff joined Reliance Electric in 1976 and progressed through increasingly responsible positions in both business and sales roles including broad experience in Rockwell’s solutions and services activities. He received his degree in electrical engineering from Akron University. With the recent split of Rockwell in to Architecture and Software?(A&S) and Control Products and Solutions (CPS)?segments, what are the implications for the company as a whole. Where does CPS fit into the global Rockwell Automation?

BR: We made the split when we spun off the power systems segment, the Reliance Dodge offerings. The reason we did it was we had to segment report the company differently when power systems left, publically, because we’re publically traded, and we felt if we didn’t split up these businesses, we may expose some of the businesses in the financial market, and we were not comfortable doing that. It makes sense when you see how well the businesses go together. Steve Eisenbrown looks after architecture and software, I have the other piece of the business.

Mine is the biggest piece of the business, we are now a $5.5 billion dollar company, and I am $3.4 billion of that. People-wise we are fairly evenly split, though we may have a little more, purely because of the size of the manufacturing facility. CPS is a lot more people-intense in its manufacture obviously.

What are your growth plans for the next 12 months?

BR: On our side of the business we made a couple of key acquisitions. Components have always been important to Rockwell, they are the foundation of what we build our products on, but going forward Keith (Nosbusch – CEO and chairman), sees us evolving in to a more solution-based and services company. We have started making some acquisitions in those areas, and we will continue to look for good, viable candidates in those areas to help us complement that business.

If you look at our business in general, it is a very healthy one, I’m referring to control products and solutions. Inherently, with where we want to go on the solutions side, I think if we can gain more direct skills, some inherent knowledge, it will help us get credibility faster in the marketplace. You can surely develop that knowledge internally, but as with IPC Triplex [a recent acquisition], we immediately gained credibility in the SIL-3 safety system side of the business. Those are the key areas we will continue in. ProsCon, is another example. Both these acquisitions fit very well in to the MPS (manufacturing and process solutions) segment, and I think we will continue to look for acquisitions to complement this side of our business.

Could the ProsCon and ICS Triplex acquisitions not have been viewed as competitive to some of your own offerings?

BR: Not really, ProsCon could have been viewed as competitive to our MPS business, but really it complements it. Again, because they had a domain expertise in life sciences that MPS was trying to develop, and I think it would have taken us a while to get there. They had it, so we picked it up! We have had very good feedback, globally, on both these acquisitions.

Rockwell’s sales in the process market grew by 27% globally in 2007, can this market maintain this growth?

BR: Yes. The process space is three times the size of the PLC space, in the overall global market. Rockwell, although we are growing very nicely, is still a small player in that process piece. In the PLC base we have dominant market share, especially in North America.?Regulatory compliance makes process a very, very, very high growth opportunity. 27% is good, but why isn’t it 35 or 40%!

Discussing major trends for 2008, Keith Nosbusch has spoken of greater emphasis on efficiency. What measures is Rockwell taking to improve energy efficiency with the use of its products, services and solutions? What more could it be doing?
I think there is a lot more we can do. In most of those cases, the efficiencies that are applied today are applied on a local basis, not a systems basis. I think there is a big opportunity for us to take some of that individualised efficiency and implement it on a plant-wide basis, and can show some real return on investment. It allows Rockwell to leverage a couple of things. Firstly, it shows we have a core competency in that area. Secondly, it gets us out of the individual pricing dilemma we are in, competing globally, The customer starts to look at value, if you can show them payback. If they are spending, for example $1m, but you can give them $10m in payback over the first year, well they stop price checking you. That is where Rockwell could gain immensely. Our solution businesses have a great opportunity to go out and become industry experts in energy efficiency or energy management and gain market share. We only have a couple of competitors that have the breadth of what we do, the Siemens and ABBs. Because the niche ‘ankle biters’ that might do variable speed drives and motor control centers, cannot compete with us on a broad spectrum.

Russia and Eastern Europe continue to be strong areas for Rockwell, in what areas do their strengths lie?
BR:?We have a great engineering capability and have built a great team of service people who give customers a confidence in Eastern Europe, We are not just there for the short term, we are there to support them long term if they make in an investment in us. One of the first things Jordi Andreu (president of Rockwell’s EMEA region) insisted on as we started moving in to Eastern Europe was for every sales person we put in there, we put in three service people, building that service foundation base. Russia is natural-resource rich, now its currency is a little more stable and has some value to it, and will provide some great opportunities for us. This may be in some of the more traditional industries like steel, or maybe oil and gas.

The skilled labour shortage in the US is dramatic. What measures does Rockwell take as a company in educating and training a future workforce?

BR: Rockwell was started in North America but we learned from Asia, when that market took off, that we needed to go and support educational institutes. I think because we were successful in doing that in China, we are able to use that in Eastern Europe now. Looking at the institutes, we make sure that we are getting technology to them so they have it in their classrooms, we are sponsoring – providing some sort of financial incentive, allowing people to enter the engineering field. The skills shortage is a shortage we feel everywhere. We have to make sure we always have that lifeline of good people coming in to the organisation. Human resources is the number one issue.

2007 saw European Union leaders agree to binding targets on the use of renewables in a bid to rapidly expand the use of green energy sources. The government signed up to a deal to ensure 20% of all European energy was to be derived from renewables sources by 2020. The UK alone has committed to cutting its emissions by 60% by 2050, although without a sufficiently skilled workforce in place to design install and maintain new technology this may not be achievable

The building services engineering (BSE) sector has a major role to play in meeting UK targets by ensuring that training structures are in place to support the move to renewable energy, which include solar thermal, photovoltaics, micro-wind, biomass, ground and air source heat pumps, and micro CHP.

As the sector skills council for the BSE sector, SummitSkills is heavily involved in a variety of activities to ensure the industry is geared up for the shift to renewable energy.

Research conducted by SummitSkills at stage two of its Sector Skills Agreement (SSA) - the Assessment of Current Provision - established that some qualification content is out of date or not suitable for sector needs, in relation to specific renewables and environmental technologies. Consequently, the UK is lagging behind in the requirements to be able to design, install and maintain technologies. As a result, SummitSkills has been updating the National Occupational Standards (NOS) for the sector to integrate renewable technologies into mainstream qualifications and ensure approved training and assessment is put in place as soon as possible.

At government level, the organisation is currently working centrally and regionally to reinforce the crucial role the BSE sector has to play in the development of the environmental technology market; with specific reference to renewables.

There is a close link between the skills of existing sector routes and new technologies. SummitSkills views this link not as new career roles, but as an extension of existing careers and industry approved qualifications, with additional specific technology training related to the work carried out. Consequently, SummitSkills has been working with the Institute of Plumbing and Heating Engineering (IPHE) to develop of the minimum technical competence requirements for the integration of environmental technologies into the appropriate Competent Persons Scheme.

Microgeneration needs
Microgeneration is a key part of the government’s strategy to help combat climate change, and is currently promoted through the Low Carbon Buildings Programme.

SummitSkills is the sector skills council for microgeneration and commissioned a report in early 2007, supported by Engineering Services Training Trust Ltd and the Heating and Ventilating Contractors’ Association (HVCA), to assess current provision and the measures in place for training on microgeneration technologies in the UK.

The report spelt out the need for the industry stakeholders to work closely with SummitSkills to champion renewable energy training on a local, regional and national level to ensure a skilled workforce.

The report resolved there are currently few microgeneration courses in combined heat and power and hydro, with only a limited number of these actually leading to a recognised qualification, particularly in wind and solar-PV. It also highlighted the lack of benchmarks for best practice in the installation of renewable energy systems, which SummitSkills feels is responsible for hindering the development of training courses It also recommends that funding is increased to improve the training facilities available.

Manufacturers and sustainability
In addition to its focus on training provision, SummitSkills also operates a Manufacturers and Sustainability Interest Group to identify and support emerging environmental technologies.

The group links with employers, professionals and employer associations to drive the government on the development and uptake of best practice in renewables. Part of its remit is to ensure technical skills training is in place, and to involve manufacturers in competence and accreditation schemes.

This group complements SummitSkills’ Interest Groups that enable employers to air their views and develop solutions for skills and training requirements in the BSE sector. This helps to form future strategies and objectives for SummitSkills.

Renewable energy in Wales
SummitSkills has been involved in liaising, on behalf of the Welsh Assembly Government, with residents to reduce the planning process for small-scale renewable energy generation equipment, such as solar panels or wind turbines.

Current laws make the process unattractive to homeowners, proving lengthy and expensive. Professional installers, surveyed by SummitSkills, believe this market could grow significantly if the planning process is improved, leading to greater productivity. The Welsh Assembly Government plans to improve energy efficiency in 200,000 Welsh homes by 2020.

Moving forward
Extensive research has established the need for change in the education and training provision in the sector. As part of its sector skills agreement, SummitSkills has taken this research and incorporated it into stage three of the project - a draft action plan that reveals five key skills priorities to be addressed in order to develop and maintain a skilled workforce.

The five priorities are:
- Professional image and competence – promoting a positive image of the sector
- Communication and information – creating a knowledge centre for all sector skills development needs
- Training provision – ensuring proactive, quality and relevant training
- Funding – flexibility in funding to meet fast-changing needs
- Management and leadership – supporting the sector to plan and develop profitable and competitive business

Tackling environmental technology provision relates directly to the third skills priority – training provision. As part of this priority SummitSkills lays out a proposed solution for the lack of appropriate skills, building on its existing work on developing and implementing National Occupational Standards (NOS) for current and emerging environmental technologies to embrace craft and professional occupations. It is key to ensuring that environmental technologies are fully integrated within other activities, such as the careers strategy and apprenticeship training frameworks.
SummitSkills’ work encompasses a broad spectrum of activities, all key to ensuring that the BSE sector has an appropriate infrastructure in place to succeed on renewable energy training strategy. It is vital not only are installers and engineers trained in these technologies, but they are trained to a recognised standard. In order to achieve this successfully, SummitSkills needs commitment from all partners within the sector for continuous improvement – only then will we see a competent, highly-skilled workforce capable of meeting the demands of the industry.

For further information on progress in environmental or renewables specific skills, visit www.summitskills.org.uk/renewables.

Liam Warren of ABB’s UK power service operation explains how the latest state-of-the-art diagnostic techniques can help to predict potential transformer faults well before they become a problem


Power transformers are mission-critical elements in many industrial, utility and power generation installations. Should an unexpected failure occur, it can result in a lengthy downtime, with consequent loss of operating revenue, and expensive repairs. Planned maintenance is the best insurance against transformer failure and that’s where advanced diagnostic techniques come in. They offer an efficient, cost-effective way of assessing the overall condition of a transformer fleet so areas of potential concern can be flagged and action taken well before a potential failure develops into a serious fault.

Furthermore, if an operator has a transformer that is already causing concern, then diagnostic tests can establish the severity of the problem, locate the fault and help the service team to provide expert advice on what action to take. For example, with regular testing it might be possible for the transformer to continue in service, while operating under a safe, reduced load, until a planned service interval is reached.

ABB’s transformer diagnostic service utilizes four main techniques – SFRA (Sweep Frequency Response Analysis), FDS (Frequency Domain Spectroscopy, winding resistance measurement and oil sampling.

SFRA
The SFRA (Sweep Frequency Response Analysis) test, carried out by a Pax FRAX-101 system, is an important tool for identifying potential winding geometry changes. It consists of a low-voltage, off-line, measurement of the impedance of the transformer windings as a function of frequency. The test is performed by injecting a variable frequency AC voltage into each individual transformer winding and plotting the responding current as a curve.
We recommend SFRA reference curves should be captured in the factory to provide a baseline ‘finger print’ of the windings in an as-new condition. However, for installed transformers, a field test can provide the baseline curves. SFRA testing should be performed periodically during the service life of the transformer, or after a specific incident that has caused significant fault currents. An alternative approach is to utilise a type-based comparison between sister transformers with the same design. Under certain conditions, a construction based comparison can be used when comparing measurements between windings in the same transformer.
When interpreted by an expert, comparison of the SFRA test with the transformer’s original baseline curves is an excellent method to check for movement or displacement of windings or winding circuits that could affect its ability to withstand faults. It is much more definitive than low-voltage impedance tests routinely performed on transformers, it helps avoid catastrophic failures and can even locate the exact position of a fault.
Figure 1 shows a typical SFRA analysis in which the pronounced dip in the frequency response curve of one of the transformer phases indicates a potential fault – most probably due either to a winding failure or core movement.

FDS
FDS (Frequency Domain Spectroscopy), carried out by a Pax IDAX-206 system, is used to assess the integrity of a transformer’s insulation system. The test determines the volume of moisture and presence of contaminants in the solid insulation, as well as the conductivity and power factor of the oil. This is an extremely useful tool in an overall condition assessment programme as standard power factor tests alone do not yield this type of information.

The FDS test measures the dielectric properties (capacitance, loss and power factor) of the transformer’s insulation as a function of frequency, This off-line test utilizes the same type of connections as a standard (Doble) mains frequency insulation power factor test . However, by covering a much wider frequency range – typically 1 mHz to 1000 Hz – the test offers increased sensitivity to insulation issues.

An important primary use of the FDS test is to determine the moisture content of the cellulose insulation structure of power transformers. It is difficult to obtain a reliable assessment of moisture content by oil sample tests, as the water is transferred between the solid insulation and the oil as the temperature changes. An oil sample has to be taken at relatively high temperatures, when the transformer is in equilibrium. But this is a relatively rare state for a transformer and can result in unreliable assessments.

An illustration of the advantages of FDS is provided by an exercise in which a customer provided ABB with a list of seven suspect transformers. In each case, moisture in oil test results had indicated the need for oil processing and drying. By carrying out FDS tests we were able to show that only two units actually needed drying. So our recommendation was to dry these two, while keeping the other five under careful surveillance. The customer not only made a very significant saving in operational and maintenance costs, preventing unnecessary drying operations on five transformers also reduced the risk of over-drying and loosening of windings.

Winding resistance measurement
Winding resistance measurement tests are carried out by an Omicron CPC 100 system. This is used to inject a DC current of up to 2kV through the transformer windings and it then measures the voltage drop across that winding - enabling the resistance to be calculated.

The main purpose of this test is to check for significant differences between the windings, which could indicate field damage or deterioration, and also to ensure that the transformer connections are correct and that there are no severe mismatches or open circuits.

Oil sampling
Just as a blood test can provide a doctor with a wealth of information about their patient, a sample of transformer oil can tell an engineer a great deal about the condition of a transformer, enabling them to effectively manage the asset for extended life and enhanced reliability.
The role of the oil in the transformer is to both cool it and insulate the internal components, and in doing so it bathes every internal component. As a result, the oil contains around 70 per cent of the available diagnostic information for the transformer and laboratory analysis can provide an early indication of a developing condition such as tap changer arcing.
The data generated from an oil sample is only as good as the sample itself. It is vital to obtain a clean uncontaminated sample to BS 5263. This includes taking the sample while warm, and measuring the temperature so that the laboratory can then adjust the results for moisture content, preflushing the sample leg and running the sample quietly into a clean glass vessel to minimise degassing and sealing the sample securely.
We recommend that the best information can be obtained from oil sampling by viewing trends. So it is useful to take a bench-mark sample when a transformer has been energized or an oil treatment performed and to then take further samples at regular intervals so that any variation in quality can be measured in order to monitor developing faults.
Typical tests carried out in the laboratory analysis of the oil sample include:
- Breakdown voltage (dielectric strength)
- Moisture content
- Dissolved gas analysis (DGA)
- Oxidation
Each of these parameters impacts on the other parameters, and they all work together to affect the condition of the transformer.

Summary
In general, power transformers are very reliable devices and will provide excellent service for many years if maintained and serviced regularly. Failures, when they occur, are usually very serious and require costly repairs and inconvenient downtime. The best insurance against failure is a planned monitoring and testing regime. The new generation of high-technology, non-invasive, diagnostic techniques can play a vital role in this regime.

Chris Smith of on365, takes a holistic look at best practice in minimising business continuity risk


Network-Critical Physical Infrastructure (NCPI), the power, cooling, equipment racks, physical structure, security, fire protection, cabling, as well as the management and servicing of these elements, is the key to minimising business continuity risk.

Without an integrated and reliable NCPI, an IT system is vulnerable. This can impede business processes and the ability of employees to efficiently carry out their tasks, weakening business profitability and competitiveness.
Traditional NCPI based on legacy architecture does not facilitate business agility. It is unable to keep up with unpredictable growth in server rooms and datacentres because of its one-time-engineered and static approach. With multiple vendor components traditional NCPI also increases the total cost of ownership, particularly through expensive service contracts.
Both these factors bring about erratic costs and poor budgeting ability. With limited IT budgets and no ability to allocate costs to individual business units, IT departments installing legacy systems try to predict what their NCPI requirements will be ten years from now and spend money on under-utilised systems that do not match current needs. By guessing power and cooling requirements five to ten years in advance and building that capacity today many organisations end up wasting, energy, capital and operational expenditures.

So where do we start?
If we wanted to build a house, we could get all the required items from the local DIY Superstore. But how do they all go together? Will one manufacturer’s radiator valve fit another manufacturers radiator? What order does everything get built in? Does one contractor’s warranty become void due to another contractors works? The list goes on.
It soon becomes clear that we need a joined up and standardised approach.

Standardisation is such a large feature of modern life we hardly notice it. From watching TV to replacing a battery, its influence is at work behind the scenes. It makes things more convenient, predictable, affordable, understandable, and safe. When we buy a light bulb, we know it will fit in the lamp socket. Our train travel is not interrupted at the border while our carriage is raised up and refitted with different wheels to match the track in the next country. Standardisation is a powerful concept that has established itself as a critical ally in managing progress.

Despite standardisation’s long track record of success in streamlining business, Network-Critical Physical Infrastructure (NCPI) has missed the turn. A steady trend toward chaos has been at work in this industry but, unlike other industries, there has been no catalyst strong enough to initiate a reversal – nothing as publicly absurd as the switching of train wheels. Systems analysts from any other mature industry would be aghast at the level of complexity and inconsistency that exists today in the NCPI of thousands of Datacentres worldwide.

The job of any infrastructure is to be functional and reliable – it is just supposed to work.

The time-tested characteristic that makes infrastructure effective, reliable, predictable, and worry-free is that it is not unique. Because of standardisation, the infrastructure of our day-today pursuits has become part of the woodwork – so commonplace and common sense that we rarely think about it. One would expect data centre infrastructure to follow the same paradigm, but until now there has been little movement in that direction. Nearly 40 years after its birth, IT physical infrastructure is still, in many ways, a craft industry: with a mish-mash of disparate components from different vendors

Apart from having no real catalyst for standardisation are there any other reasons for this poor state of our datacentres? How about P is for planning?

Planning remains a major challenge for all IT facilities. Datacentre build and upgrade projects are typically planned using methods resembling art more than science, in a process often perceived as intimidating, unstructured, and difficult. Plans are poorly communicated among the various business stakeholders within the organisation and take little notice of the principle hierarchy found in any ‘sound foundational design’.
This hierarchy begins with the determination of three fundamental IT parameters that will directly affect the design of the physical infrastructure system:

Criticality – Business importance, in terms of tolerance for downtime
Capacity – The IT power requirement
Growth plan – A prediction of the ramp-up to the maximum power requirement, frequently subject to a high degree of uncertainty.
The ‘IT parameters’ – criticality, capacity, and growth plan – that begin the physical infrastructure planning sequence are merely a refinement of concepts that will have been addressed, to some degree, during IT design. In reality, however, there exists no standardised concept or language for these fundamental parameters of IT design, so they need to be clarified and quantified before they can be used to further guide the planning sequence.

So where can we go from here?
Well a catalyst has finally started bringing in standard products, features and processes. It is cost – or the reduction of it! The IT world is no longer technology led – a black hole consuming money. It is business led and as we know business wants return on its investment.
Also the trends for consolidation, virtualisation and the drive for economies of scale have had a dramatic impact on the traditional or legacy datacentre. It now finds itself on the verge of collapse or indeed has fallen under the strain. This is due to our ability to pack more processing power into smaller spaces. The age of the blade server is upon us and it is like placing a ships anchor on a sailing dinghy. The physical infrastructures of datacentres are quickly sinking under the strain. It could be said that the datacentre is dead – long live the datacentre!
Most organisations do not have the overall expertise to design and build a datacentre. Help is required and this could include consultants, builders, facility engineers, planners, quantity surveyors, architects - the list goes on. All have there own ideas and their own agendas. Unfortunately some don’t even realise the datacentre world has changed.

on365 is a specialist in the implementation and operation of complete NCPI for business IT and communication systems, and can offer pre-planning advice for new datacentres, rationalisation plans for existing ones and complete turnkey solutions for most NCPI requirements.
on365 utilise design architecture and philosophy based on the following pre-determined business/service level goals:
Maximum availability
Scalability
Manageability
Fault tolerance
Ease of maintenance

Minimum mean time To repair (MTTR)
With these parameters clearly defined on365 can provide a complete, single vendor NCPI solution with the customer benefits dealing with just one turnkey supplier provides.

Rising energy prices are motivating industry to explore new methods – such as energy-efficient motor control solutions – for lowering operating costs. Engineers and consultants are tasked with selecting the most reliable motor control solution with the lowest total cost of ownership, which must take into consideration lifetime costs such as installation, operating efficiency, maintenance and energy use, explains Jonathan Smith, field business leader for power control at Rockwell Automation

- Since over 80% of pump and fan applications require control methods to reduce flow to meet demand, those applications are crucial to savings. Process engineers commonly use fixed-speed controllers and throttling devices such as dampers and valves, but these are not very energy efficient.
Variable-frequency drives (also known as adjustable speed drives) offer an alternative that will both vary the motor speed and greatly reduce energy losses. Advancements in drive topology, careful selection of the hardware and power system configuration and intelligent motor control strategies will produce better overall operating performance, control capability and energy savings.
Things to consider when choosing a motor control solution include peak-demand charges, operating at optimised efficiency, power factor, isolation transformer cost and losses, regeneration capabilities, synchronous transfer options and specialised intelligent motor control energy-saving features.

Beat peak-demand charges
It’s important to be aware utility companies charge higher peak-demand electricity prices when companies exceed a preset limit or base load of electricity. Peak demand charges often occur when industrial motors draw large peaks of current when started across-the-line. Variable frequency drives (VFDs) help reduce the peaks by supplying the power needed by the specific application, and gradually ramping the motor up to speed to reduce the current drawn. The VFD also automatically controls the motor frequency (speed), enabling it to run at full horsepower only when necessary. Running at lower speeds and power levels during peak times contributes to a reduction in energy costs and increased operating efficiency.
Kraftwerke Zervreila, a hydroelectric power generation plant in Switzerland, was causing a 20 percent under-voltage condition and line flicker on the electrical grid every time it started its 3.5 MW synchronous water pump motors that drew 1,600A in full-voltage starting conditions. In 2000, Zervreila retrofitted its 40-year-old motors with Allen-Bradley PowerFlex 7000 medium-voltage drives, which limited their starting current to 200A, greatly reducing its peak energy demand.

Optimise power usage
In addition to starting the motor, also consider how energy-efficiently the pump or motor operates. In applications where motors are unloaded or lightly loaded, VFDs can deliver additional energy savings and performance capabilities. Centrifugal loads, such as pumps and fans, offer the greatest potential for energy savings when applications require less than 100 percent flow or pressure. For example, significant energy savings can be gained by using VFDs to lower speed or flow by just 20%. If this reduction doesn’t impact the process, it can reduce energy use by up to 50%, which in many operations, can equate to substantial energy savings.
Energy consumption in centrifugal fan and pump applications follows the affinity laws, which means flow is proportional to speed, pressure is proportional to the square of speed, and horsepower is proportional to the cube of speed. That means if an application only needs 80 percent flow, the fan or pump will typically run at 80 percent of rated speed. But at 80% speed, the application only requires 50% of rated power. In other words, reducing speed by 20% requires only 50% of the power needed at full speed. It’s this cubed relationship between flow and power that makes VFDs energy savers.
Energy savings can also be realised by managing input power based on system demand. Vattenfall Europe Mining AG, in Germany, modernised the overburden conveyor systems of its open pit coal mine with 6.6kV Allen-Bradley PowerFlex 7000 medium voltage VFDs. The drive’s inherent regenerating capability allows fast, coordinated deceleration without the need of braking components and without wasting energy. The optimised conveyor loading (OCL) ensures system efficiency by using a material tracking system across an array of conveyors to continuously adjust speeds so that the conveyor belts are fully and uniformly loaded. A partly loaded conveyor wastes energy and causes unnecessary wear.
Vattenfall’s biggest benefit is the reduced amount of installed drive power. Before modernisation, the conveyor required six fixed-speed controllers at 1.5MW each, totalling 9MW to start the motor. The conveyor with a variable speed solution now uses installed power of only three units at 2MW each, for a total of 6MW to generate a smooth start.

Power factor makes a difference
Power factor and how it affects displacement and harmonic distortion is an important consideration in drive selection. Drives that are near-unity true power factor translate to reduced energy use. Leading drives produce a 0.95 power factor or greater throughout a wide operating speed range. An example of the effect of power factor on energy cost compares two 4,000hp drives, one with a true power factor of .95 and one with a true power factor of .98. The annual operating cost for 8,760 hours of use at

Lighting controls can deliver significant energy and performance benefits but it’s important to exploit the potential of the latest technologies, says Stewart Langdown of TridonicAtco

- When specifying lighting controls it’s very easy to achieve the minimum required by the Building Regulations but that won’t deliver maximum benefits to the end user – nor will it help to achieve energy targets that will become the norm for many buildings.
Clearly, the fact the Building Regulations now require lighting control is a step in the right direction, but the minimum requirement is simply for manual switches that are easily accessible and provide switching of lighting in zones. Also, of course, the Building Regulations don’t apply to existing buildings unless substantial improvements are being made.
So, while regulations give us a steer in the right direction, they can’t be relied on to guide specifiers to the right solution for the end user. For instance, the requirement for switches does nothing to eliminate the human factor, and it’s the human factor that forgets to switch off the lighting when a space is unoccupied or there is plenty of natural daylight available.
The real potential for controls, therefore, is to bypass the reliance on people while ensuring they still have some control over their lighting if they choose to exercise it. Obvious examples include dimming of lighting in relation to natural daylight and on/off switching using presence detectors to determine when lighting is required in a particular area. In most cases, these will be linked to a manual override.
In many cases, the maximum benefits will be achieved by combining different types of sensor to suit different areas of the building, different times of day or variable occupancy patterns. For example, the lighting may be linked to a timer that switches the lighting on at 8am and off again at 7pm. During the time the lighting is on, it may also be controlled via a photocell that measures light levels and dims the lighting when there is plenty of natural daylight. Or the lighting may only be switched on when there is someone in the space, and then controlled by a photocell to maintain the required lighting levels with the minimum use of electricity.
To that end, the way the information from the sensors is used to control the lighting is of paramount performance. At the simplest level, a single luminaire or bank of luminaires may be connected directly to a photocell or occupancy detector. The lighting is then dimmed or switched on and off directly in response to the output of the sensor – which is fine for relatively small spaces.
For larger spaces, or control of multiple spaces, a centralised control system will provide optimum control of the lighting while retaining localised control suited to the activities in each space. The more common use of electronic control gear has greatly facilitated the wider application of such control systems.
It’s over 30 years since the very first electronic control gear was introduced and we’ve seen a great deal of change since that time culminating, so far, in the Digital Serial Interface (DSI). DSI is a digital language that allows the user to switch and dim a wide range of ballasts on a pair of control wires and makes power switching a function of the ballast and not the circuit. It also allows a mixture of different lamp types to be controlled on the same circuit and the data can flow in both directions. As a result, information from the luminaire, such as lamp status, can be sent back to the central control point.
DSI has brought a great deal more ‘intelligence’ to the luminaire but the way the information is distributed around the building is also a critical factor in modern lighting control systems. To achieve this, an addressable version of the DSI ‘language’ is used - known as the Digital Addressable Lighting Interface (DALI).
DALI enables the user to address up to 64 ballasts on a single DALI network and to program both group and scene information directly into the ballast. This arrangement delivers total flexibility in design, with the added benefit of using software to configure, and re-configure, the lighting. As a result, any changes to the layout of the lighting can be achieved quickly and simply by re-programming the software, rather than altering the hard wiring.
Because it is an open interface, DALI also makes it very easy to link the lighting to other systems in the building. One obvious example would be to link the lighting controls to window blinds to make the maximum use of natural daylight while avoiding glare in the workspace.
A more recent development in this area has been the development of software that provides a ‘gateway’ between the DALI language and the language used by office networks and the Internet (TCP/IP). This has been a major breakthrough because it enables the lighting to be controlled via the building’s existing network – or from remote locations via the internet.
This software ‘gateway’ allows the user to define which buildings, fixtures and zones a particular ballast or group of ballasts is connected to, independent of the DALI circuit. It also addresses one of the key requirements of modern lighting control systems – the provision of some local control. With network based control systems, it becomes possible for each person to make adjustments to the lighting in their workspace via their PC.
Another major advantage is the ability to use the same circuit for mains lighting ballasts and emergency lighting. This means a wide range of tests can be carried out on the emergency lighting with no extra control circuitry – with full recording of results as proof the tests have been carried out. Monitoring and reporting functions include lamp failure, integrity of charging circuit, battery failure and failure of battery to sustain output for full duration.
Just as importantly, use of these systems makes installation and commissioning faster and more straightforward, despite the sophistication of the system. The DALI specification allows all ballasts on single or multiple circuits to be linked back to a local distribution board, with no necessity for special network considerations. The DALI control cables run in the same conduits as the power cables and at the distribution board the DALI signal is converted to a local area network connection.
The growing pressure to use lighting that optimises energy consumption while achieving a comfortable lit environment means that lighting controls are now a vital element in any lighting installation. Specifiers and installers that take full advantage of the technologies available are ideally placed to ensure that their customers get a solution that meets all of their requirements.

As many UK businesses find out to their cost each year, voltage surges on the electrical supply have the potential to cause serious damage to electrical equipment. That’s why the new 17th Edition of the IET Wiring Regulations contains strong recommendations for the use of surge protection. Tom France of Schneider Electric explains what’s involved

- One of the most frequent – and most damaging – causes of voltage surges on the mains electricity supply is lightning strikes. It is, however, common for otherwise well-informed specifiers and engineers to believe such strikes are comparatively rare in the UK and thus constitute a very minor problem.
The statistics show otherwise. According to the website of the Tornado and Storm Research Organisation (TORRO), in a typical year there are around 300,000 lightning ground strokes in the UK. And, on a single day with a high incidence of thunderstorms, it’s not at all unusual for there to be
10,000 ground strikes.
Remember, it doesn’t need a direct strike on an installation to cause damaging voltage surges – a ground strike in the near vicinity is quite sufficient. Also remember there are many other sources of voltage transients, such as the starting of large motors and the switching of large capacitive and inductive loads.
Taking all of these factors into consideration, it is easy to see the risk of damage to a UK electrical installation unprotected against voltages surges is, in truth, quite high. In spite of this, only a small percentage of businesses in the UK have electrical installations that include effective surge protection.
Clearly, this needs to change, and encouragement – if that’s the right word – is being provided by the new 17th Edition of the IET Wiring Regulations, which requires surge protection to be at least considered for the vast majority of commercial and industrial installations. In addition, a new standard, IEC 62305, was introduced in January 2006 and is dedicated to protection against lightning risk.
But how can this protection be provided? To answer this question, it’s first necessary to look at the types of transient that are encountered in typical installations. Around 35% of transients originate outside the site. These external transients usually take the form of single impulses with a peak amplitude of anything up to 40kV. They are most often common mode impulses, occurring between live and earth and/or neutral and earth.
The remaining 65% of transients are generated within the site. These internal transients have a damped ringing waveshape, and are considerably smaller in amplitude than external transients. In an industrial environment, for example, around 100 internal transients per year of 1kV peak, plus another 20 to 40 per year of 2kV peak would be considered normal. Internal transients are usually differential mode, occurring between live and earth.
Because internal and external transients are different in type, efficient surge protection requires the use of more than one kind of device. In practice, a three-stage arrangement is needed to achieve comprehensive protection. Unfortunately, the names used to identify the devices intended for each stage of protection are different in the various applicable standards.
In EN 61643-1, they are known as Type 1, 2 and 3 devices, whereas IEC 61643-1 refers to the same devices as Class I, II and III respectively. To complicate matters even further, the corresponding designations in VDE 0675-6 are Category B, C and D. For the sake of clarity, in this article we’ll stick with the EN 61643-1 designations.
Type 1 devices are intended for installation close to the point where the electricity supply, at low voltage, enters the building for some Industrial applications or specific installations. They are principally designed to limit the effect of high-energy external surges, and usually incorporate some form of spark gap. This diverts transient currents to earth when the applied voltage reaches the breakdown value.
After the arc is ignited across the spark gap, the short-circuit current of the power system continues to flow until the next current zero. It is essential, therefore, that the device should be able to handle this level of current, and that the transient protection provided by the spark gap is co-ordinated with the over-current and short-circuit protection provided by the circuit breakers or fuses used in the installation.
Spark gaps are characterised by a very low residual voltage and, when correctly selected, can provide good protection for the main switchboard. Because of their point of installation and their mode of operation, however, they do not provide effective protection against internal transients.
To deal with these, Type 2 devices are used and are usually fitted in each of the installation’s distribution boards. Because Type 2 devices are required to deal with lower level ringing transients, they use a different technology – metal oxide varistor or MOV. Varistors are, in effect, resistors, but their resistance decreases exponentially as the voltage applied to them rises.
This means, when subjected to the high voltage of a transient, their resistance falls to a very low value, and they effectively clamp the transient to some preset – and hopefully safe – voltage above earth. They must be selected so that they are able to dissipate the heat generated by transients, and also so that they exhibit high resistance when subjected to the normal supply voltage.
MOV devices are unsuited for use in most Type 1 applications as they have much lower energy handling capabilities than spark gaps.
Four main parameters are used to characterise Type 1 and Type 2 surge protection devices. For Type 1 devices, the first of these is the maximum impulse current, while for Type 2 devices the first parameter is maximum discharge current. The remaining three parameters are the same for both Type 1 and Type 2 devices.
The nominal discharge current is usually denoted as In. The device must be able to withstand a current of this magnitude 15 times without damage. The voltage protection level, Up, is the voltage that will appear across the terminals of the device when it is carrying the nominal discharge current. Typical values are 1.0, 1.5 and 2.0kV.
The final parameter is the maximum continuous operating voltage, Uc. This is the maximum RMS or DC voltage that can be applied to the terminals of the device without causing excessive leakage current to flow.
While these parameters may at first sound complicated, choosing devices for specific applications is, in fact, relatively straightforward, especially as comprehensive guidance is available from leading manufacturers, including Schneider Electric.
For some applications, a combination of Type 1 and Type 2 protection is all that is needed. However, with the widespread use of comparatively delicate electronic equipment such as computers, photocopiers and telecommunications systems, it is now usual to provide Type 3 protection for selected loads.
The Type 3 devices are, in most respects, similar to Type 2 devices. They use MOV technology, but they are designed to be installed as close as possible to the load, and to have even lower clamping voltages than their Type 2 counterparts. Sometimes Type 3 devices are offered in the form of plug-in socket strips with integrated surge protection.
While the correct selection of protection devices and their use in appropriate combinations are clearly important steps in providing surge protection, there is another factor that must receive careful attention. This is the effectiveness or otherwise of the installation’s earth connection.
All types of surge protection device operate by diverting surge currents to earth. If, however, the earth connection has a high impedance, the usefulness of the protection will be severely limited, no matter how good the devices are, and how well they are matched to the application.
As this article has hopefully demonstrated, the provision of effective surge protection for electrical installations isn’t, in principle, difficult. However, until recently, surge protection devices often had to be inconveniently sourced from specialist suppliers, and they were rarely designed with the needs of the electrical contractor in mind.
This situation has now changed with the introduction of a full range of surge protection equipment by Merlin Gerin, a brand of Schneider Electric. Not only are the devices in the range backed by comprehensive guidance on selection and applications, they also provide protection which is fully co-ordinated with Merlin Gerin circuit breakers.
Additionally, the devices are presented in a convenient DIN-rail mounting format, ensuring that they are easily accommodated in standard switchboards and distribution cabinets. These features make it much easier and more convenient to provide surge protection in both new and existing installations.
When it comes to ensuring continuity of operation in industry and commerce, surge protection is vital. In fact, it is no exaggeration to suggest, in the near future, an industrial or commercial installation without surge protection will be as unthinkable as an installation without over-current or earth leakage protection. Fortunately, as we’ve seen, it is now possible to provide comprehensive surge protection easily and cost effectively.

Most electrical installations depend on earthing via earth electrodes to protect people and equipment. In these installations, regular testing of the earth resistance is essential, but most testing methods are either time consuming and inconvenient, or prone to giving inaccurate results. As Paul Swinerd of Megger explains, however, there is now a better alternative

- It’s tempting to think checking the resistance of an earth electrode should be no more complicated than finding a second earth connection, such as a nearby water pipe, and measuring the resistance between this and the electrode under test with an ordinary ohmmeter. Unfortunately, life isn’t quite that simple.
Noise currents flowing in the earth will almost certainly produce large errors in the results obtained, and there’s no way of knowing how much of the resistance is due to the secondary earth connection and how much to the earth electrode itself. In other words, some sort of result will be obtained but, for all practical purposes, it is meaningless.
For this reason, a number of alternative methods have been devised for accurately measuring earth resistance. The simplest is to carry out a direct measurement, as described earlier, but with a purpose-designed earth tester that uses an ac test current. By choosing the frequency of this current so it is not an integer multiple of the mains supply frequency, it is possible to arrange for such an instrument to provide a high degree of noise rejection.
The results are far more meaningful than those which might be obtained with an ohmmeter, but there is still no way of confirming that they are accurate or, indeed, of separating out the contribution of the secondary earth.
A much better method, and one which is very widely used, is usually known as the three-terminal or fall-of-potential method. This uses a connection to the electrode under test and two test spikes that must be driven into the ground before the test is carried out.
One of the spikes – the current spike – injects the test current, and should be placed as far away as possible from the electrode under test. The other spike – the voltage spike – is then driven into the ground at a number of locations, preferably in a straight line, between the current spike and the electrode. At each location, a voltage measurement is taken. Since the current injected by the instrument is known, each of these voltage measurements can be converted, using Ohm’s law, to a resistance value. In practice, this conversion is performed by the instrument itself.
If a graph is plotted of resistance versus the distance the voltage spike from the electrode under test, it should have a definite plateau region where the resistance hardly varies as the rod is moved. This value of resistance is the required earth resistance for the electrode under test.
This method is accurate, and any problems with the measurements are readily apparent, as the resistance graph will depart markedly from the expected shape. The only shortcomings are that the test is time consuming to carry out, it requires a reasonable amount of space, and that the earth electrode under test must be disconnected from all other circuits while the test is underway. These are rather significant shortcomings.
To provide a more convenient way of measuring earth resistance, the clamp-on or stakeless method was introduced. This uses a tester adapted to inject a test current into the earth electrode system via a clamp arrangement, and uses the same clamphead to measure the resulting current flowing in the electrode under test. No direct connections are required, and the earth electrode does not need to be disconnected from other circuits – indeed, for successful testing, it cannot be.
While this method is quick and easy, it has several limitations. It only works in applications where there are multiple parallel earth connections so that there is a return path for the test current, and it cannot, therefore, be used to test isolated electrodes. Since there’s no way of verifying the result, it is also unsuitable for checks on new installations where no previous test results are available for comparison, but it is good for trending of earth system condition.
A new solution, which is more versatile than the stakeless method and more convenient than the traditional fall-of-potential method, is provided by the Attached Rod Technique (ART). In many ways, ART is similar to fall-of-potential testing, and all of the same connections are required. There is, however, one crucial difference – there is no need to disconnect the earth electrode from other circuits while the test is being carried out.
That may seem a relatively small advantage but, apart from the physical difficulty of breaking earth connections, it's important to remember that earthing is a safety function.
There are dangers in disconnecting an earth electrode as a fault current may be flowing and disconnection could give rise to a potentially lethal situation. Furthermore, if equipment is disconnected from the earth electrode to enable a test to be carried out, that equipment may no longer be safe, and dangerous situations may result.
While it may be possible to provide a temporary earth connection, or to switch off the electricity supply during the test, such measures are likely to be both inconvenient and costly.
So how does ART testing work? The key is in a current measuring clamp (ICLAMP) that is put round the earth electrode under test. The tester is designed to ignore any system leakage and noise currents that may be flowing through the earth electrode. This means that it can accurately measure the test current, in spite of extraneous influences.
With the equipment set up, the ART test proceeds in exactly the same way as an ordinary fall-of-potential test. It is still, therefore, time consuming, but there are a number of shortcuts that can be used in appropriate circumstances.
For example, instead of taking readings with the voltage spike at various distances between the electrode and the current spike, it is sometimes sufficient to take a few readings, with the voltage spike around 62% of the distance between them. This means that ART testing provides a very good balance between convenience and accuracy of results.
For earth resistance testing, it is important to have the right equipment and to understand the limitations of the various test methods – even ART testing isn't suitable in every case, although it is very versatile.
Earth resistance testing isn’t particularly complicated, but interpreting the results from the various test methods can be, which is why Megger has developed software that will do the earth testing calculations automatically, and supply a report.
Megger also offers an 80-page publication "Getting Down to Earth" which provides detailed practical advice on all commonly used methods of earth resistance testing. Printed copies are available free of charge from the company, or the publication can be downloaded from the Megger website (www.megger.com).

If you are a user or potential user of Valve Regulated Lead Acid (VRLA) batteries this article may be of some interest to you. matt jordan of yuasa answers some of the questions often asked by installers when considering the use of a VRLA product in applications such as Telecommunications, Stand-by UPS, Fire and Security, Mobility and Leisure markets. By following these recommendations, service life and performance of the product will be enhanced

What precisely is a Valve Regulated Lead Acid Battery?
VRLA batteries have been designed to maximise the use of gas recombination technology and can be used in modern office environments, removing the need for expensive purpose built battery rooms etc. They utilise the latest cell plate technology with each cell comprising a number of positive and negative, lead calcium alloy plates, which are filled with either lead dioxide (positive) or spongy lead (negative) active materials. Unlike motor car batteries the electrolyte (Sulphuric Acid) is trapped in a gel substance or, in the case of a Yuasa product, suspended in absorbent glass matting (AGM), which is located between positive and negative plates. Each cell has a voltage of 2V. Therefore, a 2, 6 or 12V battery will comprise one, three or six cells respectively. The battery container and lid are commonly manufactured from ABS (Acrylonitrile-Butadiene-Styrene) which are welded together to form a high integrity leak-proof seal. The container lid contains a number of low-pressure valves, which are designed to release excess gas and reseal automatically in the event of the internal gas pressure rising to unacceptable levels. A VRLA battery effectively recombines 99% of the gas generated in normal use at 20°C.

How can I do a simple battery sizing?
To carry out the most basic battery sizing for a portable tool for example, you must establish: (a) DC output voltage of the tool i.e. 6, 12, 24V etc. (b) load (amps) of the tool and (c) length of time (autonomy) the tool needs to be supported by the battery i.e. battery back up time. Note. If the tool is rated in watts, simply convert to amps by dividing the watts by the nominal voltage of the equipment. Determine if there are any physical constraints that may affect your selection, such as: application; environmental; temperature or dimensional restraints. Then, using Figure 1, which denotes a series of graphs based on time against current (amps) for a selection of Yuasa NP batteries, a battery selection can be made. NB. Battery sizes are normally calculated in the UK based on an ambient temperature of 20 to 25°C. At higher temperatures, the capacity of a battery increases while life expectancy decreases and, conversely, at lower temperatures, the capacity decreases.

Is it possible to increase the DC voltage and capacity (Ah) by connecting VRLA batteries together?
Voltage can be increased by connecting the positive terminal of one battery to the negative terminal of an adjacent battery. Therefore, connecting four 12V 7Ah batteries together in this manner will effectively raise the voltage across the battery from 12 to 48V. Battery capacity will remain at 7Ah. This is commonly termed ‘series’ connection. Capacity can be increased by connecting the positive terminal of one battery to the positive battery of the next. Negative terminals could be connected together in a similar manner. Therefore, connecting four 12V 7Ah batteries will effectively raise the capacity available across the batteries from 7 to 28Ah. Battery voltage will remain at 12V. This is commonly termed ‘parallel’ connection.

The connection of the batteries in series and parallel will increase both capacity and voltage. Note. It is recommended that consultation with the battery manufacturer be made before connecting “mixed” product types in series or parallel.

What does the term 20-hour and 10-hour mean?
Battery manufacturers rate capacities (Ah) against specific times (hours) to a specified end of discharge voltage. For example, a Yuasa NP product is rated at the 20-hour rate. Therefore, the NP7-12 VRLA battery will support a constant load of approximately 350mA (7/20) for 20 hours to an end voltage of 1.75V per cell (VPC). It will not support a constant load of 7A per hour for 20 hours. Discharging the battery over one hour will reduce the efficiency of the battery to approximately 60% of the battery’s rated capacity (4.2Ah in the case of a 7Ah battery) and will therefore support a constant load of 4200mA for this period.

What do the terms eg. ‘2C’ or ‘2CA’ mean in relation to a battery manufacturer’s published documentation?
Battery manufacturers often publish data that refers to the ‘C’ or ‘CA’ rates. Discharge curves being a typical example. Both terms refer to current (Amps) in relation to the capacity (C) of the battery. Therefore, for a Yuasa NP7-12 battery ‘2C’ equates to a current of 14A (2 x 7) and ‘1C’ or ‘C’ for the same battery relates to 7 Amps etc.

What do the terms ‘Standby’ and ‘Cyclic’ applications mean?
Standby refers to battery applications designed to support AC mains failure, such as emergency back up for alarm panels, emergency lighting, UPS systems etc.

Cyclic refers to battery applications where the battery is repeatedly charged then discharged, independently, from the charging source. Typical applications are portable equipment, wheel chairs and electric golf trolleys etc.

Can I use a standard motor car charger on my VRLA battery?
We do not recommend permanent use of car battery chargers, unless the charger has a VRLA setting. To maximise the service life and performance of a VRLA battery, it is essential the correct charging regime based on the specific type of application be used. Car battery chargers charge at a higher voltage than we would normally recommend for standby applications and, if these higher voltages are left continuously connected to a VRLA battery, it will cause irreversible damage. It is also recommended VRLA batteries be recharged after use. Never leave a VRLA battery in discharged state.

What is the correct charging regime?
This depends on the type of application ie. ‘standby’ or ‘cyclic’. In both types of applications, constant voltage charging is recommended. For standby applications, using the Yuasa NP range of batteries, the voltage of the charger should be set to give a constant voltage of 2.275V per cell at 20°C ambient. This relates to a value of 13.65V for a 12V block (6 x 2.275V).

For cyclic applications a higher constant charging voltage is used but should NEVER be left on indefinitely since it will overcharge and eventually destroy the battery. The voltage of the charger should be set to a level of between 2.4 to 2.5V per cell at 20°C ambient. This relates to a voltage of between 14.4 to 15V for a 12V block.
For standby or float we recommend that the current be limited to a maximum of 0.25CA i.e. 25% of the capacity of the battery in Amps. Typically for an NP7-12 this value would be 1.75A.

What sort of service life can I expect from my VRLA battery?
For standby applications, battery manufacturers produce a range of batteries that are designed to give a pre-determined service life, usually 5, 10, and 15 years if used as per the manufacturer’s specification.
Towards the end of service life, battery capacity will reduce resulting in reduced run times. Operating the battery at temperatures above ambient 20 to 25°C for prolonged periods will shorten the service life of the battery.
For cyclic applications the service life of batteries depends on (a) quantity of cycles of charge and discharge and (b) the depth of discharge as expressed as a percentage of the capacity required per duty cycle. Most VRLA products can be cycled.

What can I do if I need support on a VRLA product?
If unsure of any safety or operational aspects associated with the use of VRLA batteries, always check with the supplier or original manufacturer.

Over the last decade or so, field wiring for automation installations has been completely transformed by the widespread adoption of fieldbus systems. Surprisingly, however, this revolution has had little effect on the wiring inside control panels. That’s about to change, says Paul Bennett of Moeller Electric

Few would deny the fieldbus systems used in automation applications bring major benefits. Not only do they dramatically reduce the amount of field wiring required, they also virtually eliminate the risk of wiring errors and, possibly best of all, they make it easy to modify the installation if the configuration of the plant changes.

But open the control panel door, and inside you’ll almost invariably find conventional control wiring, like that previosly used in the field. And this old-fashioned panel wiring shares all the disadvantages of old-fashioned field wiring. It’s complicated, open to wiring errors and the only way to make changes is to re-wire the circuits involved.

Surely there has to be a better way – why can’t the fieldbus benefits be enjoyed within the control panel? There’s no fundamental problem with the technology. Fieldbus technology would work within the panel, but present-day fieldbus systems are not a good match for in-panel applications.
The first reason is cost. With fieldbus systems, the cost of the hardware is invariably more than balanced by the savings made on cabling. Inside the panel, however, the situation is different – connections are short, so the reduction in cable cost is minimal. The hardware for in-panel bus systems must, therefore, be inexpensive if it is not to increase the panel price unacceptably.

In-panel systems also need to be simple to use as panel builders have neither the inclination nor the time to work with complicated configuration systems just to link, for example, a few motor starters. Finally, the system must be compact, given today’s pressures for ever-smaller panels.
For these reasons, automation product suppliers have seen little attraction in developing in-panel bus systems. However, progress in technology means that this situation has now changed – the time is right for bus technology to move into the panel, so let’s take a look at what an ideal in-panel bus system might look like.

To minimise space requirements, add-on auxiliaries for contactors are designed so that they add little to the overall dimensions of the contactor, and it makes good sense to adopt the same idea for in-panel bus adapters.

But what of the connections themselves? Screw-clamp terminals, for instance, are a poor partner for modern bus technology. Plug-in wiring is a much better choice; it cuts wiring time dramatically and also virtually eliminates the possibility of wiring mistakes.
To be easy to use, the system should offer automatic addressing, and should also be capable of automatically reconfiguring itself when items are added to or removed from the bus.

Naturally, the in-panel bus must offer direct connection to PLCs, since this will enable significant cost savings to be achieved by eliminating the need for conventional PLC I/O modules. And, users shouldn’t be tied to PLCs from one specific manufacturer.

Open connectivity could be achieved by providing support for one or more of the popular automation communication protocols such as CANopen or Profibus. This approach has the additional benefit of allowing the in-panel bus system to connect easily with conventional fieldbus installations.
We’ve mentioned some of the benefits that an in-panel bus-based connection system can bring but there are many others. The time required to build the control panel is reduced, which makes it easier for panel builders to meet tight customer deadlines. Panel builders can also start building panels sooner, even if requirements have not been finalised, safe in the knowledge that last minute alterations can easily be accommodated.

The time needed to test panels is also reduced, since the potential for wiring errors is minimal. Finally, maintenance throughout the life of the installation is made easier – if a starter is damaged, for example, it’s only necessary to unplug the connections to it, clip a replacement in place, and replace the plug-in connections. No conventional wiring is needed.
Before we close, however, it’s necessary to sound one note of caution. To maximise the benefits of an in-panel bus system, it’s important to choose one that has been specifically designed with this application in mind. While it may be tempting to try to shoehorn a conventional fieldbus system into the panel, this is not ideal. The modules are, for example, likely to be too big, too expensive and probably too complicated.
When the appropriate technology is used, in-panel bus systems, as we’ve seen, have a lot to offer. In fact, it’s very likely that, in a few years’ time, conventionally wired control panels will be as rare as conventionally wired field installations are today. But there’s really no need to wait – the technology and the benefits are available right now!


BEST CONVEYORS BUILDS A SMARTER PANEL
Faster to wire, easier to test, neater in appearance and simpler to maintain – that was the considered opinion of Best Conveyors after the company had finished building its first control panel to use Moeller Electric's new SmartWire wiring system.

"Although SmartWire is very new, it didn't take long for Moeller Electric and local dealer, Automation Technology of Daventry, to convince us of its benefits," said Gavin Hogan, Managing Director of Best Conveyors. "We could see immediately that it offered opportunities for simplifying panels and for cutting build time."

"These factors are very important to us, as it's becoming increasingly difficult to find skilled panel wirers," he continued. "Another attraction was the use of standard starters, so we could work with easy-to-obtain components, and the changes needed to our designs were minimal."

The project selected by Best Conveyors to evaluate SmartWire was a telescopic conveyor system for a major distribution warehouse. Developed in conjunction with Automation Technology and Moeller Electric, the control system uses a programmable relay, in conjunction with a remote I/O unit at the far end of the telescopic conveyor, which greatly simplifies the field wiring.

Within the panel are five reversing and two unidirectional motor starters which feature motor circuit breakers and convenient plug-in connections between the contactor and the protection device. In this application, the power to the starters is provided by a prefabricated busbar system.
For use with the SmartWire system, each starter is fitted with an interface module that clips into place like an auxiliary contact block. Since the SmartWire modules fit on top of the contactors, no extra space is needed in the control panel.

With the modules in place, all Best Conveyors had to do to complete the control wiring was to link the modules together with pre-assembled daisy-chain plug-in cables, and then make one final plug-in connection to the gateway on the easy 800 relay.

"It sounds simple," said Gavin Hogan, "and it genuinely was. It's virtually impossible to make a wiring mistake with SmartWire. Even the module addressing is taken care of automatically. It really would be hard to go wrong.”

Best Conveyors found that a further benefit of using Moeller Electric components was the availability of the easy MFD multi-function display module. With its integral function keys and LCD screen, this provides the features of an entry-level HMI module at low cost. Linked to the easy800 relay, the MFD module allowed Best Conveyors to develop an intuitive user interface for the conveyor project.

"Adding the SmartWire modules did slightly increase the cost of components for the panel," said Gavin Hogan, "but the extra cost was outweighed by the savings on wiring, on wiring time and on testing time."
"Using the easy800 and the MFD unit instead of the ordinary PLC and HMI panel that we used on previous projects provided further cost savings," he said, "without us having to make any compromises in the performance of the system. In fact, the easy800/MFD combination is so cost effective it's like getting the HMI functionality free."

Following its positive experience with SmartWire, Best Conveyors is now planning to use it extensively in future projects.

The recent widespread flooding in the UK has undoubtedly damaged electrical equipment worth millions of pounds. In some cases, however, it may be possible to restore this equipment to safe and reliable operation, thereby avoiding the need for costly replacements. Jeff Jowett of Megger looks at what can be done

The key to salvaging flood damaged electrical equipment is to find ways of drying it out effectively, without risking further damage. A number of options are available for this. Probably the most satisfactory is to use a temperature controlled oven with efficient air circulation but, in many cases, this is not possible either because the equipment is too large to be moved to an oven, or because no oven is available.

In these cases, infrared lamps can be used, or a housing can be built around the equipment, with steam coils or electric elements used as the heat source. It is important to make provision for free circulation of air, so that moisture is allowed to escape, and the use of blowers can be helpful.
Another method of heating sometimes used with items like motors and transformers is to pass a current at low voltage through the windings. To avoid the risk of further damage, however, this should not be done until the insulation resistance has been raised to at least 100,000 ohms by other methods. Insulation testers that have kilohm ranges are invaluable in this type of work.

On occasion, welding sets are used as a current source for drying out windings. It’s important to note that these are not intended to supply high currents continuously and they must, therefore, be used at only a fraction of their rated current.

Whichever method of heating is used to dry out the equipment, it’s vital to monitor the insulation resistance for a long enough period to ensure that it has reached a stable value. It is very common, during the drying process, for the insulation resistance to rise to a comparatively high value then dip again. In fact, this rise and fall is often repeated several times as moisture works its way out of the equipment.

While the comments above give general information on salvaging flood-damaged equipment, it is worth looking in more detail at what can be done with various specific types of equipment.

Switchboards and Electrical Controls
- Thoroughly clean and dry out all equipment, dismantling where necessary. After drying, re-varnish all coils. Check contacts for corrosion and oxidation, and make sure that all moving parts operate freely.
- Drain all oil-filled devices, clean them and re-fill with fresh oil of the correct dielectric strength. The oil can be tested for conformance with British Standards using a test set. Dry all insulating barriers, or replace them if they have warped.
- Meters and protection relays will usually have to be reconditioned by the manufacturer. To ensure fast return to service, it may be preferable to fit replacements.
- Clean and dry thoroughly all busbar insulators and control wiring. A minimum of two megohm insulation resistance must be achieved before the equipment is energised, and can readily be confirmed by any good quality insulation tester.
- Check standby batteries for functionality using a battery impedance tester, and check battery straps for corrosion or excessive resistance using a purpose-designed low-resistance ohmmeter.

Electrical Tool and Portable Appliances
- Many of the techniques outlined in the introductory section of this article are suitable for salvaging wet tools and appliances. Before these items are returned to service, however, it is essential that final proof testing is carried out with a portable appliance tester (PAT) in line with IEE code of practice for in-service inspection and testing. As a further precaution, it may also be desirable to flash test Class 2 assets

Rotating Electrical Machines
- Completely dismantle all parts and, except for ball and roller bearings, and either wash them with clean water or steam clean them. Follow this with a thorough cleaning using a grease solvent.
- Thoroughly clean all bearings and housings paying particular attention to oil grooves and reservoirs. Disconnect and swab oil lines, or steam clean them.
- Dismantle the brush rigging and clean the insulators. Some types retain water and must be dried very thoroughly.
- Monitor the insulation resistance of the machine with a modern tester that uses a low applied voltage for the kilohm ranges. Once a value of at least 100,000 ohm is reached, the megohm ranges of the instrument can be used for further monitoring.
- Commutators can be hard to dry out, and it may be necessary to loosen or even remove the clamps to let water out of the inside of the commutator. On large commutators, it may be necessary to use drying temperatures as high as 130°C to achieve effective results.
- Check the bands on armatures or rotors for tightness, as the drying out of the underlying insulation may loosen them. If this happens, they will need to be replaced.
- Some slot wedge materials may be affected by moisture. If this has happened, new wedges must be installed.
- Field coils from DC motors, generators and synchronous machines can present particular problems, and it may be necessary to remove them from the machine for drying in an oven and re-varnishing. After this, the coils should be checked for shorted turns with a digital low-resistance ohmmeter.
- After cleaning and drying, most windings will need re-varnishing. Dip-and-bake varnish is recommended but, it the original varnish is in good condition, an air-drying varnish may be used.
- Before starting the machine, check the entire installation, paying particular attention to lubrication and electrical connections. For three-phase machines, check the phase rotation.

Transformers
- Remove inspection cover plates and check the condition of the windings, looking particularly for signs of failure. Check all connections for looseness and signs of heating. With oil insulated transformers, draw oil samples from top and bottom, and check them with an oil test set. Breakdown should be at least 22kV, or 25kV if an askarel is used. If it is lower, the oil/askarel will need to be replaced.
- Check the insulation resistance. This should be at least one megohm for each 1,000 volts rating, with a minimum of two megohms. Ideally, the resistance should be comparable with the pre-flood values, which may be available from maintenance records. This is best confirmed by an insulation tester with an extended range, such as Megger’s MIT400 and MIT510 products.
- Note the condition of the bushings, external connections, operating switches and protective devices, and take remedial action where needed. If necessary, clean the transformer externally and paint the tank.
- If water has entered the tank, flush the windings with clean insulating oil. If the transformer is small, remove the coil and core, and dry in an oven at up to 90°C. If necessary, dip and bake the windings. Windings for larger transformers can be dried in the tank by forcing hot, dry air (not above 90°C) around the windings after the tank has been drained; by short-circuiting one winding and energising the other with a low voltage; or by using a combination of these methods.
- During the drying process, plot a curve of insulation resistance against time, initially measuring with a low-voltage tester and subsequently, if the process proceeds successfully, changing to a high-voltage insulation tester. If the process is not successful, and the curve shows no sustained increase in insulation resistance, the transformer will need to be re-wound.
- When the insulation resistance has reached an acceptable value, a final test should be made with a transformer turns ratio tester to confirm the transformer has been returned to full performance.

Cables and Wiring
- All open wiring, including non-metallic sheathed cable, can usually be retained after thoroughly cleaning and drying the cable and the junction boxes, and remaking connections.
- Armoured cable will usually have to be replaced, as will lead cable if the ends have been under water.
- Rubber-covered cable in rigid conduit can sometimes be reused, but it must be pulled out of the conduit so that the conduit can be cleaned. The conduit must be thoroughly cleaned to remove all silt and moisture before being used again.
- Check and clean potheads and other insulators, and inspect them for cracks or other damage
- Perform a comprehensive insulation resistance test before returning the installation to service.
Hopefully, this article will have given a useful indication of the measures that can be taken to salvage electrical equipment after it has been subjected to flooding. It is essential, however, to remember, in every case, safety is of paramount importance. This can only be assured by careful testing of the salvaged equipment, during and after the repair process, using appropriate test equipment.

Mike Frain looks at the dangers of live testing and fault finding in industrial and commercial low voltage electrical installations

In advising industrial and commercial companies on electrical safety rules and procedures, I make enquiries to every delegate on training courses about their own experiences. A good percentage have said that they have experienced electrical flashover (arc flash) and I have yet to meet anybody who has never received an electric shock. Most of us know it takes a very small amount of current flow through the body to cause death. Where death has not occurred this is due simply to the fortuitous nature of the current path in missing vital organs. What is required therefore to survive an electric shock from mains voltage is luck!
When someone is killed or injured by electricity what first comes to mind is electrocution but electric shock is not the only hazard. There are several hundred serious burn victims each year as a result of electrical flashover and is a source of long-term injuries and sometimes a slow and painful death. Many electrical staff routinely work on live high power equipment, carrying out tasks such as fault finding and diagnostic testing without fully understanding the consequences of what will happen to them should an electrical flashover occur. This article is written to highlight the dangers from electrical flashover and recent research to better understand its effects.

LIVE WORKING
Live working is defined as “work on or near conductors that are accessible and live or charged”. This is anywhere a worker is exposed to energised conductors, terminals, busbars or contacts and that often includes the removal of fuses and links. In industrial and commercial environments this usually means live diagnostic testing, faultfinding, non-invasive inspections such as thermal imaging and some tests in accordance with BS7671 Wiring Regulations. Even if it is intended to carry out work on dead conductors, an assumption should be made that they are still live until proven dead.

Whilst live connection work is routinely undertaken by utility distribution network operators (DNOs), any work that requires the connection and disconnection of live conductors and components in most industrial and commercial premises would be extremely difficult to justify.

Live working should never be accepted as the norm and Regulation 14 of the Electricity at Work Regulations 1989 makes clear three conditions must be met for live working to be permitted. These conditions are:
1. It is unreasonable in all the circumstances for the conductor to be dead
2. It is reasonable in all the circumstances for that person to be at work on or near that conductor while it is live
3. Suitable precautions (including where necessary, the provision of personal protective equipment) have been taken to prevent injury
If live working can be justified through the rigorous tests of reasonableness in conditions one and two, judgements must be made about suitable precautions against electric shock and the effects of electrical flashover to satisfy the requirements of condition three

ELECTRICAL FLASHOVER
Electrical flashover is usually caused by inadvertent contact between an energised conductor such as a busbar with another conductor or an earthed surface. This is often the result of incorrect use of test probes, faulty or poorly specified instruments or dropped tools and can be made more likely when the equipment is subject to condensation, dust or corrosion. The magnetic field from the resultant fault current will cause the conductors to separate or the tool to be blown back producing an arc, which ionises the air, making a conducting plasma fireball. Electric arcs produce some of the highest temperatures known to occur on earth and can be up to 35,000 degrees Fahrenheit, which is four times the surface temperature of the sun. This is enough to immediately vaporise all known materials and this sudden release of thermal energy at the point of the fault can cause severe burns to the skin, internal burns to throat and lungs due to inhaling vaporised metal or heated air, ignition of clothing, blindness from the resulting ultraviolet light and even death. The effects of the flashover can radiate several metres away from the point of the arc, injuring other people that might be nearby.

When an electrical flashover occurs, conductors can vaporise expanding to thousands of times their original volume and the high release of thermal energy superheats and rapidly expands the surrounding air. The result can create a pressure wave called arc blast, which is literally an explosion. During this violent event, molten metal particles, destroyed equipment and related components will be ejected as shrapnel at speeds of up to 700 miles per hour.

LOW VOLTAGE POWER SOURCES
European statistics demonstrate that serious electrical accidents resulting from fault arcs occur mainly in low voltage power installations. Fault levels in many industrial and commercial networks can be surprisingly high and can lead to larger and more catastrophic flashover events. This does not necessarily mean you are safe working on systems that have lower prospective short circuit currents as at lower levels, overcurrent devices can operate more slowly allowing the arc to last longer producing a high overall amount of energy at the point of flashover.

The electrical utility industry adopts a rigorous task based approach to risk assessment of live working on low voltage systems and yet the fault energy in many cases is actually lower than can be found in some medium sized manufacturing plants. There are many instances of electrical installations that incorporate low voltage distribution transformer sizes of between 2MVA and 3 MVA as well as having generators and large motors that will contribute to total fault energy. At least one UK utility company (DNO) uses protective measures to cover 7,000A to 10,000A of arc current. In industrial processes and some commercial premises the amount energy that can be generated in an arc can be much higher than this, low voltage fault levels of 40,000A are quite common which will raise the level of arc energy.

NORTH AMERICAN RESEARCH
Experience shows many employers have no idea of the destructive nature of such fault energy should an incident be initiated by an employee. The difficulty has been that until recently there has been limited knowledge available to predict the amount of harm to a worker whose screwdriver or test probes slip whilst working in an energised control panel. Recent studies particularly in the United States have started to address this and there are now methods of calculating the amount of harm to workers and bystanders. This has enabled the North Americans to specify relevant work place precautions from flashover or arc flash hazard as it is commonly referred to. There are two US standards that apply to arc flash; NFPA70E-Standard for Electrical Safety in the Workplace and IEEE 1584- Guide for Performing Arc Flash Calculations.

As a very brief summary, the basis of the calculations relies on input data such as; fault level, voltage, gap between conductors, enclosure type, working distance, method of earthing and protective device characteristics. From this data, the amount of thermal energy from an arc can be determined that can reach a surface such as a person’s skin. A figure of 1.2cals/cm2 is considered to be the energy required to produce the onset of a secondary degree burn and this is used as a benchmark for the need and type of PPE such as flame retardant clothing and the Flash Protection Boundary. The Flash Protection Boundary is defined as “An approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur.” The IEEE 1584 calculation methods have been derived from actual laboratory experiments involving the simulation of electrical flashover events. There is ongoing research in the US into the arc flash hazard and a further $6million has been allocated this year. However, the effect of arc blast, which accounts for the pressure wave and shrapnel from a flashover, is still relatively unknown.

NEXT STEPS
You should make sure that you have written – and up to date – safe working practices to for people who carry out any work on or near low voltage electrical systems. The HSE guidance note HSG85 Electricity at Work – Safe Working Practices is an excellently written and valuable resource in this respect. It clearly sets out decision-making flowcharts on whether to work live or dead and also gives some guidance on live working procedures.

The ability to calculate flash protection boundaries will enable managers to arrive at better-informed judgements before allowing live proximity work to proceed in the first place and provide an ability to apply quantitative techniques to risk control. There is software available but only trained individuals should undertake arc flash calculations, as any study should take account of variables due to system configuration for example.
Finally, if you have influence over the design of electrical systems then a goal will be to eliminate the need to work live at all in maintaining those systems. Some of the measures that can be employed are the segregation of power and control circuits, safe control voltages and currents, finger safe shrouding of terminals and built in test facilities.

Mike Frain FIET MCMI is MD of Electrical Safety (UK), advising industrial and commercial organisations on electrical safety procedures. He has held senior management positions in contracting, utilities and facilities maintenance companies having direct responsibility for putting people to work on a full range of complex and large power electrical systems.