Features

There are a number of drivers affecting energy performance in modern buildings, some of which impact upon the work of the electrical design engineer, challenging him to produce cost-effective solutions but also presenting new business opportunities. Mike Lawrence, product line team leader - commercial assemblies at Eaton, explains

Principal among the drivers affecting energy performance is the Building Regulations Part L2: Conservation of fuel and power in buildings other than dwellings. This calls for sub-metering so that at least 90% of the estimated annual consumption can be attributed to specific end-use categories.

Some energy metering systems offered by manufacturers are complex and costly. However, the solution does not necessarily have to be so complex. Sometimes it is possible to install a relatively simple, cost-effective system that is future-proofed to allow more advanced automatic metering and trending (AM&T) systems to be introduced later.

Energy Performance Certificates
Since October 2008 an Energy Performance Certificate (EPC) has been required by law for any new building or any building sold or rented. First introduced for domestic premises, the requirement was extended in April 2008 to cover large commercial properties. Then in October it became applicable to all buildings, or parts of buildings, when they are "built, sold or rented". In addition, since October a Display Energy Certificate (DEC) has been required for prominent display in larger public buildings.

The EPC and DEC are among a number of interrelated requirements of the European Energy Performance of Buildings Directive (EPBD).

Energy Performance Certificates must be issued by accredited energy assessors. They will give the property an energy efficiency rating on a scale of A to G, similar to the ratings used for domestic appliances. The assessors will also give recommendations for improvement.
While the requirements for Energy Performance Certificates do not impose any direct requirements for metering, a carefully-planned sub-metering strategy will enable building owners or occupiers to monitor energy usage, identify significant trends and assess the effectiveness of measures taken to implement the energy assessors' recommendations.

Building Regulations L2
The UK Building Regulations Part L2 was also driven by the Energy Performance of Buildings Directive. It is published as two documents, L2A covering new buildings and L2B covering existing buildings.
The key requirements affecting sub-metering are:-
- Energy meters should be installed so that at least 90% of the estimated annual energy consumption of each fuel (electricity, gas, LPG, oil etc.) can be assigned to various end-use categories such as lighting, heating, ventilation, pumps and fans.
- Reasonable provision of energy meters in existing buildings can be achieved by following the recommendations of Cibse Technical Memorandum TM39:Building Energy Metering (A Guide to energy sub-metering in non-domestic buildings.)
- Reasonable provision of energy meters would be to install sub-meters in any building greater than 500m2.   
- In buildings with a total useful floor area greater than 1000m2, facilities should be provided for automatic meter reading and data collection.
The objective is to develop a sub-metering strategy so that users can identify areas where improvements can be introduced to achieve energy savings of 5-10% or better.
TM39 is an updated version of Cibse General Information Leaflet 65 (GIL65):Metering energy use in new non-domestic buildings, which can be downloaded free of charge from www.cibse.org/pdfs/GIL065.pdf

The L2 requirements apply to premises with a floor area greater than 500m2 and existing buildings where "consequential improvements", normally involving Building Regulations approval, are being made. This includes separate buildings on multi-building sites.
Specific recommendations are made for plant and equipment for which separate metering should be provided as follows:-
- Motor control centres feeding pumps and fan loads greater than 10kW
- Boiler installations greater than 50kW
- Chiller installations greater than 20kW
- Electric humidifiers greater than 10kW
- Final electricity distribution boards greater than 50kW
This last recommendation is especially pertinent because the majority of distribution boards are rated higher than 50kW.

Metering solutions
There are various approaches to sub-metering. In some cases all metering is provided at the main switchboard. This has the advantage that meters are all in the same location so manual collection of data is easy. However, on some sites MCCB panelboards provide sub-distribution to final distribution boards and to loads such as lifts, ventilation or air-conditioning plant. These will require sub-metering at the panelboard.

Final distribution boards frequently supply more than one type of load (typically lighting and small power). If these loads are metered separately back at the main switchboard or panelboard, it will require separate feeders and probably two distribution boards instead of one. If, however, metering of the grouped loads can be carried out at the distribution board it is possible to use a single feeder.
Different solutions are available at the final distribution board:-
- Custom-built boards incorporating metering. This is generally an expensive solution.
- Separate meter packs installed below, or alongside, standard distribution boards offer a more cost-effective solution.
- Distribution boards with integral metering are now available as standard products.

In each case there are options for a single meter to monitor the entire board, or for split metering to provide separate measurement of grouped lighting and small power loads. These options are available with both Type A (single-phase) and Type B (three-phase) boards. However, it should be noted that in some split metering applications one meter monitors the entire board. This calls for external calculation for one group of MCB-ways.
It is recommended that meters should always include remote reading capabilities. As a minimum this should be a pulsed output offering remote measurement of kWh. A better solution is a Modbus design that provides information via an RS485 connection. With Modbus RS485 communication, information is read directly from the meter and some data registers, such as peak demand, can be re-set remotely. If the meter is connected to an effective energy management system (EMS/BMS), it can deliver a more informative energy monitoring capability. Specifiers and installers do not need to go to the expense of custom-built distribution boards and panelboards to ensure compliance with Building Regulations Part L2. A range of metering solutions is now available for type A and type B boards including add-on meter packs for use with standard distribution boards and distribution boards with integral metering capabilities. The design of these units minimises the amount of on-site work for the contractor and the standardised design allows boards to be sourced through the normal electrical wholesaler network.

Where greater sophistication is required, ethernet connectivity can be used to integrate the sub-metering into a comprehensive energy management architecture for effective monitoring, control and management of the complete energy infrastructure in large sites. Eaton's Power Xpert software allows energy use to be monitored and trends identified so that systems can be optimised to reduce energy costs and achieve a more efficient system.
For further information see www.poweringbusinessworldwide.tv

Management of waste on site is becoming increasingly complex. Bryan Neill of Mercury Recycling explains why this is, and explores the special case of discharge light sources

As our understanding of sustainability evolves, much of the thinking now extends beyond simple matters of energy consumption to encompass other environmental issues. One of the most important of these is the management of waste, because all of the materials we use have embedded carbon, so wasting them makes a contribution to climate change.

In addition, we are running out of space to store waste - and a lot of the waste we generate contains environmentally harmful substances that shouldn't be consigned to landfill.

These concerns have not only fostered a greater awareness of waste, they have also spawned a raft of legislative measures to minimise waste. Furthermore, there is a great deal of pressure on companies to demonstrate corporate social responsibility through efficient management of issues such as sustainability. And when it comes to waste, the construction industry is one of the worst offenders.

In fact, according to government statistics, over 70 million tonnes of waste is produced by the construction industry every year. Some of it is necessary waste that can't be avoided but, amazingly, an average of 13% of all the materials delivered to site never get used - they are simply discarded.

All of these factors can impact on the electrical engineer; from the way that systems are designed through to the management of the project on site. For example, on a major project the main contractor will be operating a site waste management plan that involves everyone on site.

Also, there may be smaller projects where the electrical engineer is the principal contractor with responsibility for legislative compliance. So having an understanding of waste management requirements is important in avoiding non-compliance and possible prosecution.

Within the electrical services, lighting can be one of the most challenging areas to manage, because light fittings fall within the remit of the WEEE (Waste Electrical & Electronic Equipment) Directive, while discharge light sources are also classified as hazardous waste.
There are a number of situations where disposal of electrical equipment becomes an integral part of a project, ranging from a fit-out through to refurbishment and demolition projects. In all such cases, it's no longer acceptable to simply throw the old light fittings, control panels and any other electrical items in a skip. Under the WEEE Directive these need to be sent for recycling through an accredited waste stream. And if there are light fittings containing discharge light sources (e.g. fluorescent, metal halide, sodium) the lamps must be removed from the fittings and treated as hazardous waste. This clearly has implications for anyone involved in managing waste on site.

Disposing of WEEE
Many items of WEEE will be covered by manufacturers' take-back schemes so a key element of waste management will be to identify which accredited schemes can be used to dispose of waste. This may lead to separation of different types of waste on site, with provision for appropriate storage until they are collected. Very often, it makes sense to source an accredited waste contractor that can handle any type of WEEE and take these complexities off your hands.

As noted above, though, if the waste includes discharge lamps then it's important the waste contractor is licensed to handle hazardous waste as well. It is also important to separate the lamps from the fittings. Old luminaires are usually sent for shredding and the residual materials re-used in industry, but a single lamp can contaminate the whole batch so that it all has to be treated as hazardous waste. Apart from the additional treatment costs, this can lead to prosecution under environmental legislation.

The special case of lamps
The special status of discharge light sources is the result of their containing small amounts of mercury. Lamp manufacturers have made considerable progress in reducing the total amount of mercury in lamps and using mercury amalgam rather than liquid mercury - particularly in fluorescent lamps. Nevertheless, a small amount is still required and when one considers the cumulative effects from the millions of such lamps that are disposed of each year are considered, it's clear that there is the potential for sloppy waste disposal to inflict significant damage on the environment.

The first piece of legislation to impact on disposal of discharge lamps came into force in July 2004, and significantly reduced the total number of hazardous landfill sites in the UK. At the same time, the cost of sending such waste to landfill sites tripled, so the pressure was on to find alternatives.

Then came the Hazardous Waste Regulations in England and Wales, introduced in July 2005, which classified discharge lamps and tubes as hazardous waste. As a result, these light sources then attracted a hazardous waste consignment fee when they were transported anywhere.

Up to this point it was still theoretically possible to send waste lamps to special landfill sites, albeit it at a high cost. Since the WEEE Directive came into force, though, this has not been an option and all such waste has to be sent for recycling.

Again, the recycling of discharge lamps is considerably more complex than most other forms of WEEE. In fact, discharge lamps are among the most difficult types of waste to deal with because they are made up of many different materials.

For instance, the glass in many lamps is coated with a mixture of phosphors and this has to be stripped off before the glass can be re-used. These phosphors also contain mercury, which is distilled from the phosphor mix at very high temperatures (around 800°C) to reclaim pure liquid mercury. In the case of sodium lamps, the sodium is also reclaimed. Ferrous and non-ferrous metals are also separated from other components and sent for re-use.
Furthermore, the vacuum within the lamps means they implode when crushed so the crushing procedure has to be contained within specially constructed machines. Highly flammable hydrogen gas is also released when the sodium from sodium lamps is exposed to` water, so special precautions have to be taken with this both when processing and storing these lamps.

Consequently, it's important to select a waste contractor that has the expertise to deal with such waste, and has invested in the advanced machinery and techniques to ensure that 100% of the lamp components are dealt with in compliance with the requirements of the legislation.

Managing on site
Clearly, then, on-site waste management is becoming more important. It is now necessary to establish disposal points for different types of waste and to ensure that all operatives on site are familiar with how the waste needs to be sorted.

A typical arrangement might include skips for general construction waste, another skip for non-hazardous WEEE items such as luminaires and a separate, secure storage area for hazardous waste such as lamps. The latter is very important because of the potential for contamination of the site if lamps are broken. For instance, if broken lamps were left lying around on site the mercury could be washed away by rain and contaminate the surrounding land. If there are water courses nearby, these could also be affected. And, of course, any associated major clean up will inevitably lead to delays in the construction schedule.
As a result, any waste lamps need to be stored in secure containers that will not allow such leakage. And, because the waste is hazardous, their location will also need to bear all necessary signage. A specialist waste contractor should be able to provide appropriate storage containers and signage - along with all of the necessary documentation to ensure a complete audit trail is in place.

On your own doorstep
While most Electrical Review readers will be most concerned with the issues of waste on site, it's important to bear in mind that the same considerations apply to disposing of waste from your own premises. Most local authorities now offer facilities for smaller volumes of WEEE but in the case of larger offices it will again make sense to employ the services of a specialist waste contractor.

Here it's important to point out another significant element of the Hazardous Waste regulations for building operators. This is that any site producing more than 200kg of any type of hazardous waste per annum has to register with the Environment Agency as a hazardous waste producer. Registered sites receive a site registration code and waste contractors are not allowed to collect waste from any site that does not have this code.
To put 200kg of waste into perspective, this constitutes around 500 fluorescent tubes, or around 15 CRT monitors - therefore many office buildings need to register as hazardous waste producers. And if you have several offices, it may be necessary to register each one separately.

Disposing of potentially harmful waste is clearly important if we are to safeguard the environment and the health and safety of people who may come into contact with such waste. However, this can be a complex area where it makes sense to take advantage of specialist advice and expertise.

Each month, Electrical Review's resident grumpy old man, writer and industry commentator John Houston, explores a hot topic of the day and lets us know his views in no uncertain terms

The demise of the 100W incandescent lamp may be greeted warmly by anyone with a green streak and I too welcome any moves that reduce energy consumption. But, there is almost always a ‘but' when it comes to energy efficiency, carbon footprints and other conservation issues. Saving the planet is never as simple as it seems and most attempts to make life easy seem to throw up equal and opposite arguments.

Let's consider one basic problem with killing off the 100W and higher rated lamps.  Compact Fluorescent Lamps (CFL) - the luminaire most recognised as an ‘energy saving light bulb' - do not work with electronic switches.  Indeed, using CFLs with dimmer switches can cause overheating in the lamp holder, the switch and thereby also significantly shortening the life of the five times more expensive and supposedly longer lasting CFL!

This means anyone with dimmer switches must fit only 80W incandescent lamps and below in future. Yet, crediting the populace with some intelligence, in practice such lighting is frequently, if not mainly, operated in a dimmed state. Arguably a suitably dimmed 100W lamp potentially saves as much as using a CFL, but without the higher price of the lamp itself.
If one considers safety, the likes of stairwells and corridors that have sensibly and responsibly been equipped with occupancy sensors to switch on lighting only when required, are doomed because such applications cannot afford the delay time associated with the operation of the CFL.  Presumably, these applications will be compelled to use 80W lamps rather than, say, the 150W versions once deployed to give adequate lighting for safety purposes.

The issue throws up far greater challenges than whether of not the removal of higher power lamps from western marketplaces is worthy or not. My issue with the control of the availability of such lamps is that it once again illustrates the over simplification of legislation.
Using CFL and low energy lighting in most cases merely mitigates for the otherwise greater waste of energy that would occur when lights are left switched on unnecessarily. It does nothing to change neither the habits nor the controls that really dictate our energy wastage.
As an analogy, let us consider applying the same legislative logic to motoring.  We all know that the bigger the car, the greater its emissions don't we? Surely then, it would make sense, at least in the short term, to limit all personal vehicles to, say 1.5 litre diesel engines wouldn't it? However, emissions are highest in stationary traffic, whatever the engine size. Hence, we need also to control traffic flow - perhaps by levies, traffic bans or restricted usage.  But, what about people's driving style? Those with a heavy right foot on the accelerator pedal, whatever the engine size, will emit more than others.  So, with such logic, should all vehicles be automatics, with governors fitted?

The point at issue, before too many readers lambast me for being of the Jeremy Clarkson school of devil may care scepticism and cynicism, is not what we do, but rather how we do it. Let me state right now that I am in favour of reducing carbon emissions, reducing energy waste and generally saving the whale, the world and all exists within it. What I find frustrating is the naivety of legislators and the essence of the nanny state some moves induce.

Banning incandescent lamps above 100W at this stage is posturing.  I suggest it may be borne out of a lack of imagination as to how better to encourage people to save energy. This I can fully appreciate.  Lighting and other energy controls cost money and with a credit crunch, global recession and general lack of confidence, it's a brave person who invests in the ‘unknown' of energy efficiency controls.  But, there's never been a better time to invest; for the payback is short on most items installed - certainly shorter than the return on investment of a CFL.

Those like me that are packing far too many additional inches in all the wrong places welcome low fat, low sugar, high fibre foods provided they taste good (however rare that may seem). Unfortunately, the awful truth for most of us is that we have too many inches because we eat too much nice, tasty bad stuff, while never leaving our seats for most of our waking hours!

So too, if we really want to save the planet, we really need to change the habits of a lifetime and do more than fit a few CFL lights. 

 

Following a review of the outdated standard IEC 60439, radical changes have been made and the new IEC 61439, governing the safety and performance of electrical panels, now better meets the low voltage assembly market's needs. Although the changes are fundamental it may take specifiers some time to adjust. Here Mark Waters from Schneider Electric explains the changes, why they have been made and how to meet the requirements of the new standard

Although some specifiers are worried by the changes, IEC 61439 has been introduced to enable panel and systems builders in the UK to produce assemblies that meet essential quality standards and mean compliance is unavoidable, bringing a welcome reassurance of quality within the industry.

As Schneider Electric was a significant lobbyist in persuading the IEC to investigate revising the old IEC 60439 standard and subsequently consulted on the new one, it has given the company's experts a unique insight into the background, requirements, and implications of the new standard.

Why is it needed?
IEC 61439 has been urgently needed for many years, for the previous 35-year old IEC 60439 series of standards were lacking in a number of areas. It was a compromise between different national approaches, some of which were strict and others that were more subjective. Where agreement could not be achieved, the subject was ignored, or some vague clause was added that could be interpreted to suit the reader's point of view.
It has been obvious for some time that the foundations of the old standard were fundamentally flawed when considered in the context of today's industry. Designs and market requirements for assemblies have evolved over the years, such that IEC 60439-1 no longer encompasses many commonly used arrangements. Just one of these for example is modular systems, under the old standard these are not effectively covered with respect to the critical matter of temperature rise performance.

It is well known that it's not practical to fully type test every conceivable configuration of assembly produced and so where type testing was not feasible, there has needed to be alternative ways of ensuring an assembly meets the minimum required safety and performance criteria.

The old methods for proving the design of a 'partially type tested assembly' in accordance with IEC 60439-1 were weak and relied entirely on the capability and integrity of assembly designers. Previously there was no standard for assemblies that do not fit within the categories of type tested or partially type tested, therefore the old standard was no longer suitable for today's industry.

These weak foundations have made it difficult to evolve the standard in line with market needs and pressures. Every assembly manufactured should meet minimum performance and safety criteria, in spite of ever increasing demands to optimise manufacture and reduce costs.

The new approach
With the growing pressures for higher network utilisation, assembly design optimisation and more stringent safety regulations, the changes included in the assembly standard IEC 61439-2 are important and long overdue. All assemblies that do not have a specific product standard are covered and there is no opportunity to avoid compliance.

In the new standard, the methods of confirming design performance are practical, reflecting the different market needs and ways in which assemblies are produced. Several alternative means of verifying a particular characteristic of an assembly are also included. These are defined and their use restricted. Overall, the standard is performance based, but in some instances where design rules are used, it has to be prescriptive.

Essential changes
In order to meet its objectives, the review of the IEC 60439 series of standards had to make changes and these have been radical ones. A number of foundations of the old standard have been discarded, in order to have a standard that better meets the low-voltage assembly market's needs and the way it operates.

Under the previous standard, panels can be type tested assemblies (TTA) or part type tested assemblies (PTTA), but since many panels are too small to be covered by TTA or PTTA certifications, they fell outside of any standard. Therefore the categories of TTA and PTTA have been discarded in favour of a design ‘verified assembly'. This is a classless term, where demonstration of design capability can be achieved by type test and/or by other equivalent means that include appropriate margins.

The IEC 61439 series of standards uses the same structure as other series within IEC. Part 1 is General Rules, detailing requirements that are common to two or more generic types of assembly. Each type then has a product-specific part within the series. This then references valid clauses within the General Rules and details any specific requirements belonging to that particular type of assembly. Any clause in the General Rules that is not in the product-specific part does not apply. Part 2 of IEC 61439 is the only part that has a dual role, it covers power switchgear and control gear assemblies as well as any assembly not covered by any other product specific part.

The structure of IEC 61439 also makes revisions easier, as changes to ‘General Rules' will always tend to lag behind their introduction in product-specific Parts. It also means that assemblies cannot be specified or manufactured to IEC 61439-1, since one of the product-specific Parts must be referenced in any assembly specification.  Parts (3, 4, 5 and 6) are currently being prepared by the IEC to cover all product specific Parts from the old standard and more could be added at a later date.

As business becomes more global there is the increasing need for portable designs. This is now fully recognised as the new standard confirms that designs and design verifications are portable. For example, subject to a suitable quality assurance regime being in place, a type test certificate obtained in France, for a design carried out in the UK, is valid for an assembly manufactured in Australia.

For the first time the new standard recognises that more than one party may be involved between concept and delivery of an assembly. IEC 61439 identifies the original manufacturer as the one responsible for the basic design and its verification and possibly, the supply of a kit of parts. It then designates the manufacturer who completes the assembly and conducts the routine tests, as the assembly manufacturer.

The original and assembly manufacturer can be the same, or, a transition may take place somewhere between concept and delivery. In any event, all parts of the assemblies must be design and routine verified by a manufacturer.

Responsibilities
The new standard attempts to focus all parties on their respective responsibilities. Purchasers and specifiers are encouraged to view an assembly as a ‘black box'. Their prime task is to specify the inputs and outputs to the assembly and to define the interfaces between the assembly and the outside world.

How the assembly is configured internally and the performance, relative to the external parameters (as defined by the purchaser or specifier) is clearly the responsibility of the manufacturer(s). They are legally responsible for the correct configuration of the individual parts and must ensure the design meets the specification, is fully verified and fit for purpose.
Compliance with the new standard is compulsory. All assemblies must be shown to meet minimum safety and performance standards by design and routine verification. Once the European equivalent standard, EN 61439-2 (BS EN 61439-2) has been listed in the Official Journal of the European Union, full compliance will become the easiest route to ‘presumption of compliance' with the Electromagnetic Compatibility and Low-voltage Directives, both of which are essential before the CE mark can be applied. Partially proven design or only routine testing of some assemblies is forbidden.

The majority of assembly manufacturers and builders are already competent and diligent, and so the new standard will not mean significant changes. IEC 61439 requires a logical approach to the design and verification of an assembly, which is essentially just good practice.

However, where previously partially type tested assemblies or those outside of the scope of IEC 60439-1 have been provided, the panel builder may find it beneficial to purchase a basic design verified assembly in kit form, from a manufacturer such as Schneider Electric. This will enable the panel builder to avoid the time and cost of much of the design verification process.

Most modern businesses heavily rely on Telecoms, it and other electronic systems - take them away and many companies would struggle to function. The new British Standard, BS EN 62305 Protection against lightning, makes a welcome step forward by introducing procedures that will give a much greater level of protection against an electrical surge. UK contractors need greater awareness of the requirements of this new Standard, says Andy Malinski, technical director at Omega Red Group 

The damage and degradation caused by transient over-voltages to electrical systems have long been understood by electrical engineers in Europe and elsewhere. In the UK, high voltage (HV) surge arrestors are installed as standard components in the electricity supply infrastructure, fitted to avoid costly network downtime, but there still appears to be a strong reluctance to fit surge protection devices (SPD) to the low voltage (LV) networks used in commercial and domestic environments.

With only an advisory appendix for surge protection in the previous British Standard the reasons for this reluctance probably have more to do with an ingrained resistance to change rather than any hostility to the new standard. Surge protection is included for reasons of good working practice rather than some unnecessary bureaucratic standardisation with our European neighbours.

As before, the new Standard covers the need to provide structural protection but it now also addresses the need to offer protection to electrical and electronic systems against lightning currents and transient over-voltages.

Since the new Standard was introduced in September 2008 the construction industry should have noticed a change in response from contractors to their enquiries about lightning protection systems. Surge protection devices (SPDs) form an integral part of BS EN 62305 and need to be installed for a fully compliant lightning protection installation. 
Additionally there are now four different protection levels which can be applied for structural lightning protection. The level of protection is dependent on the outcome of a risk assessment which is far more complex than the outgoing standard and has many new factors to consider including building services, occupancy hours and number of people to list a few. For the UK construction industry this involves a steep learning curve. In any event, service entry SPDs will be required on all four structural protection levels for compliance.
In real terms why do we need SPDs and what should we all be doing about them? The answer is very simple. If the cables entering a structure have been exposed to lightning, either via a direct strike or by induction, then the conductive cores of the cable may carry dangerously high voltages in to the structure leading to sparking at the termination points due to the break down in the insulation of the cables or equipment.

This theory is not only being applied to the service entry points, which is a minimum requirement, but also to any exposed plant or other electrical/electronic units being fitted to the structure. Plant items on the roof (AHU etc), a control system for electric gates, car park lighting, CCTV systems may all include copper cables entering or leaving buildings.
There are three ways in which transient voltages can be introduced into a structure via copper cables:

Resistive coupling
A cloud to ground lightning strike injects a massive current into the ground raising the ground potential in the area of impact to a high level and for the current to dissipate it will seek the path of least resistance to earth. Cables running between buildings are usually connected to different earthing systems at each end and a cable connected to an earth of a lower value forms an ideal route for the induced current to follow.

Inductive coupling
A lightning discharge causes a huge current to flow; this in turn sets up a massive magnetic field.  Any conductor passing through this magnetic field will have a surge voltage induced on the cable; this is the same principle on which a transformer operates.

Capacitive coupling
Atmospheric disturbances cause high voltages to be generated.  A low voltage conductor in the area of influence of these voltages can be charged to that same voltage, this has the same effect as charging a capacitor.

Any cable entering or leaving a structure may carry back a problem but the installation of SPDs at the nearest point of entry or exit will reduce the effect of a surge. It is important to note that the service entry or equipotential Bonding SPDs are designed to handle a 10/350µs current and are commonly referred to as lightning current SPDs.

The purpose of these frontal surge protection devices is to divert partial lightning current away to earth and limit the let-through voltage to a safe level in order to prevent dangerous sparking. A competent installation company, with appropriately trained staff, should be able to advise the contractor on the best units to use - it is vital to check they comply with BS EN 62305-4 and IEC 61643.

You may be wondering why, after all these years under the previous British Standard, do we need to be looking at surge protection? The answer in very simple terms is progression; outside of the UK and especially within Europe, surge protection has been a common part of lightning protection installations for many years and the value of surge protection is well established.

BS EN 62305 has incorporated guidance and Standards employed within the UK, Germany, France and many other countries, taking available technology and applying it across the industry, just as we have with other Standards and systems in the past. The Germans have a simplified method of SPD selection which is based mainly on the use of the building to be protected and is endorsed by German insurance companies. This has evolved after many years experience and incidence recording and could well be replicated within the UK in years to come.

Under BS EN 62305 SPDs are now an integral part of lightning protection designs. It is also important to remember the certification of a system; failure to provide the entry surge protection units will mean a non-compliance with the Standard. Engineers need to understand a new system installed to BS EN 62305 should have service entry surge protection fitted as a minimum. These units should be compliant with the Standard's requirements or they may fail in the task they have been designed to carry out.

Omega Red Group has invested a great deal of time and effort in training for the design and installation of SPDs and lightning protection systems. Of course, any contractor would expect its chosen installer to know what they are talking about but a sound grasp of the requirements of the new standard is necessary to identify whether that is the case. Our engineers will always be happy to answer any questions you might have but a good starting point for understanding the basic principles of BS EN 62305, especially the SPD components, can be found in a short webcast tutorial at http://www.omegaredgroup.com/

More than 50 senior figures from the electricity industry gathered at London's Royal Automobile Club on 5 February 2009, for NetWork 2009 - the first ever international DNO strategy conference. Top of their agenda was how the ability to measure the condition of live assets is making the management of network assets more efficient, at lower cost. Neil Davies from EA Technology Instruments investigates

The inaugural NetWork 2009 event in February was an extremely valuable opportunity for UK DNOs to share knowledge on the key strategic management issues facing network operators and learn from the examples  of two of the world's most reliable and efficient networks - SP Powergrid of Singapore and China Light and Power (CLP) of Hong Kong.
The pressures are common to every operator across the world: how can they manage an ageing asset base so that it will deliver greater network reliability, power quality and safety, while reducing costs to consumers? At the same time, how can they make a watertight business case for investment in maintaining, upgrading and replacing assets to stakeholders, including industry regulators?

The answer to these questions is being found in two developments which are inextricably linked: new techniques for accurately measuring the condition of live assets, plus new methodologies for managing assets more effectively, based on their actual condition.
Let's look at what has been achieved in Hong Kong and Singapore, where condition based asset management has become the driver for remarkable improvements in both reliability and cost efficiency:

SP Powergrid, Singapore
SP Powergrid's network includes nearly 10,000 substations, 40,000 switchgear sets, 14,000 transformers and 30,000km of cable. Since incorporating condition monitoring into its systems, it has dramatically improved an already excellent performance. The System Average Interruption Duration Index (SAIDI) has averaged less than 1 minute per year over the last three years.
NB: The blip in 2004/5 was caused by a third party supply issue outside SP Powergrid's control.

SP Powergrid estimates over the last eight financial years, condition monitoring has enabled it to avert 450 network failure incidents, with a net financial saving of US$29m. In addition to improving customer service, it has been able to pass cost savings on to them.


CLP  Hong  Kong
The China Light and Power network in Hong Kong includes nearly 13,000 substations and 22,000km of overhead lines and underground cables, serving 2.26 million customers.
As a result of focusing over the last 10 years on condition based maintenance, to predict faults and improve reliability , it has reduced its SAIDI figures from more than 40 to 2.68 minutes lost per year

Demand from customers has continue to grow, but in the last two years, greater operating efficiencies have enabled CLP to reduce tariffs.

The UK Business Case
Taken as a whole, the UK electricity network is relatively efficient. But an in-depth analysis by EA Technology Consulting of preventable, condition-related failures, shows there is considerable scope for improvement:
Using condition monitoring as a failure prevention tool is a valuable technique, but is only part of a much wider move towards condition based asset management techniques.

Using Condition Data
The ability to collect data on the condition of live assets is transforming the industry's approach to asset management itself: from one based on time-scheduled maintenance and replacement, to one based on a detailed understanding of the condition of the asset base. It also provides accurate intelligence for investment programmes.
Maximising the value of  data is essentially carried out at two levels:

Asset condition registers
Expert analysis and interpretation of PD activity readings gives a clear indication of the condition of assets, including accurate predictions of when they are likely to fail. In EA Technology's case, this is based on a unique database, built up over more than 30 years, which shows how tens of thousands of asset types have deteriorated over time.
This approach enables operators to develop registers of assets, in which each asset is accorded a ‘health index' showing its present condition, its predicted date of failure and/or its remaining service life.

Condition Based Risk Management (CBRM)
CBRM is a comprehensive new methodology, which takes condition based asset management to a higher level, enabling managers to take more intelligent decisions on revenue and capital spending. It also reduces the cost of network operation, while improving their efficiency and reliability.

The effectiveness of CBRM derives from factoring together probability (derived from the asset condition) and consequences of asset failure, to determine risk in terms of financial cost.
In addition to managing the health of assets, CBRM provides the answers to the key questions:

- If an asset costing £XX fails, what will be the consequential loss to the business? 
- If an asset is refurbished or replaced at a cost of £YY, what will be the benefit to the business?
- Therefore, where should we prioritise our spending?


EA Technology's experience shows that partial discharge (PD) activity is a factor in around 85% of disruptive substation failures. It has thus become increasingly clear the ability to detect and measure PD is key to assessing the health of assets. PD activity provides clear evidence that an asset is deteriorating in a way that is likely to lead to failure.  The process of deterioration can propagate and develop, until the insulation is unable to withstand the electrical stress, leading to flashover.

Partial discharges emit energy, in the form of effects which can be detected, located, measured and monitored:
- Electromagnetic emissions, in the form of radio waves, light and heat.
- Acoustic emissions, in the audible and ultrasonic ranges.
- Ozone and nitrous oxide gases.
The most effective techniques for detecting and measuring PD activity in live assets are based on quantifying:

Transient earth voltages (TEVs)
The importance of TEV effects (discharges of radio energy associated with PD activity) was first identified by EA Technology in the 1970s. Measuring TEV emissions is the most effective way to assess internal PD activity in metalclad MV switchgear.

Ultrasonic emissions
PD activity creates emissions in both the audible and ultrasonic ranges. The latter is by far the most valuable for early detection and measurement.  Measuring ultrasonic emissions is the most effective way to assess PD activity where there is an air passage e.g. vents or door in the casing of an asset.

UHF emissions
PD activity can also be measured in the UHF range, and is particularly useful in monitoring EHV assets.

The latest PD instruments typically use a combination of ultrasonic and TEV sensor technologies, characterised by the EA Technology UltraTEV range. These include:

- Handheld dual sensor instruments which provide an instant indication of critical levels of PD activity, ideal for ‘first pass' PD surveys and safety checks. Traffic light warning levels are precisely calibrated using a database of known patterns of asset deterioration.
- More sophisticated handhelds, which provide audible and numerical readings of ultrasonic and TEV activity.
- PD location instruments which pinpoint and quantify the source of PD activity.
- PD monitoring instruments, which measure, record and analyse PD activity over time.
- PD alarm systems, which give immediate warning of critical PD activity in groups of assets or whole networks.
- Specialist PD monitoring systems for strategically important assets, including Gas Insulated Switchgear (GIS).

Other Asset Classes
Condition based management is by no means confined to assets which present faults in the form of PD activity.

The same principle is equally effective, using a range of condition measurement techniques, to all types of electricity network assets including substations and cables. It can apply to the complete asset, such as an overhead line, as well as to the component parts, such as the overhead conductors, poles, towers and footings.

Conclusion
The ability to assess the condition of live assets is changing the way assets are managed on many levels: as a technique for preventing faults from developing into failures, as a means of moving from time-based to condition-based maintenance, as a way of quantifying risk and as the basis for justifying and prioritising investment.

But the ultimate rationale for condition measurement is that it pays for itself, many times over.

This article includes material from presentations made at NetWork 2009, the first international distribution network strategy conference, held in London in February 2009. The full presentations are available from www.networkconference.co.uk, where readers can also register their interest in  NetWork 2010.
For further information please email This email address is being protected from spambots. You need JavaScript enabled to view it.

Thorn Lighting has opened a £32m factory and Academy of Light in Spennymoor, County Durham, which the company claims to be the largest investment in lighting equipment manufacture and training in the UK since the 1940s.

Thorn has transferred production to the site, on the Green Lane Industrial Estate, from its previous base in nearby Merrington Lane, which it had occupied since 1952. The Merrington Lane site was sold to a UK-based property developer in December 2008.

The 40,000 sqm building also hosts a manufacturing facility for Zumtobel Group's Tridonic Atco luminaire components business. Overall the operation employs approximately 700 people, excluding indirect jobs at suppliers and local businesses.

Fronting the building is the Thorn Academy of Light Competence Sharing Centre, designed to provide sales staff and customers with application-specific training. The first training sessions feature Sustainability in Lighting, with half the fees raised being donated to the Lighting Education Trust.

Thorn has also expanded and upgraded its laboratory, which now features full automation of thermal test measurements, a fully anechoic EMC test chamber, expanded materials and life test facilities, and temperature control to all laboratory areas.

Helen Goodman, MP for Bishop Auckland, who officially opened the complex, said:?"This kind of investment shows, even in the current economic climate, progressive and innovative companies like Thorn still have real confidence in the the future of the local economy."
Stewart Watkins, managing director of the County Durham Development Company, endorsed Goodman's comments:?"Thorn Lighting is a beacon for manufacturing excellence in County Durham. Here we have an example of how a traditional manufacturing business has embraced the global challenges and met them head on. By investing in new production facilities, coupled with training and future development, it has ensured the long-term future of lighting production in this area."

New Labour in a nutshell

Given the government's determination to be the first to raise money by selling the right to pollute (see story below), you might think that our Lords and Masters would be determined to auction the maximum number of EU emissions trading allowances that European rules permit. Not so.

After all, there has been a considerable scandal attached to the way in which all the electricity generators have managed so far to get all their emission allowances for free. But then have promptly put up all their prices on the pretence they had bought the permits on the open trading market. Consequently they are now receiving windfall profits worth around £ 70bn. That is right. £70bn. All paid for by we consumers.

It is, therefore, entirely reasonable for the generating companies to be forced to pay out of their own pockets for the maximum number of permits permitted. Which up until 2013 is just 10% of the allowances set aside for the electricity industry.

Fair enough, you might think. The government could take the money in from at least that 10%. And maybe follow the example of the Dutch or the Austrians, and ring-fence the money to help poorer people cope with these inflated power bills?

So is that what is planned? Not on your life. The UK government has decided it won't take up the right to sell all 10% of the allowances to the generators. Instead, it has decided to take pity on these poor penurious multinationals. And just auction 7%. Rather than the permitted 10%.

Why have the Whitehall mandarins decided to hand out the extra 3% free and gratis, and so forgo around £600m. Money that could have gone to help eliminate fuel poverty. Apparently, the official explanation is that they were worried that if they did auction more than just 7%, they might overshoot that 10% maximum. Such caution might have justified limiting the amount to be auctioned to (say) 9.75. But only 7%? Phooey.

Oh ,and apparently it is "not government policy" ever to ring fence revenues for any specific piece of expenditure. Instead at the start of this financial year, the government celebrated by cutting the main fuel poverty programme, Warm Front, by 20%. It is New Labour's philosophy in a nutshell: Take away from the poor. Give to the rich.

Pipped to the post

Such is the decline in the value of the pound that, in its rush to be the first European government to auction  allowances under the EU carbon emissions trading scheme, ministers have ‘lost' the taxpayer around £10m.

This is because the entire trading system - which covers all types of electricity generation -   only recognises the euro as a currency. In consequence, all such auctions have to be in euros. But whereas,  when the sale took place in mid-November, the pound was worth 84 eurocents, right now it is around parity - in other words, worth one whole euro.

With the right to emit each tonne of carbon dioxide selling at 16.15 euros, this converted to an income for the government of some £54m in November. However, had the government waited until the New Year, the exchange rate would have upped the value to around £64m. I really don't think the loss of revenue was worth the dubious honour of pipping all those other European governments to the post to start auctioning.

Can't beat them? Join them

Back in 2006, the government set up a competition. It offered to pay the majority of the costs to build the first 400 megawatt Carbon Capture & Storage (CCS) demonstration plant.
Most of the Big Six electricity generators decided to compete. Last July the government announced which  schemes were on the short list. The German power company RWE, which trades here as npower, was mightily miffed when its entry was eliminated.

It huffed and puffed. It announced it was considering legal proceeding against the government. For six months m'learned friends were rubbing their collective hands with glee, at the prospect of a lengthy full-scale battle in the Courts.

But then suddenly the threat of Court proceedings disappeared. Why? Because RWE has gone and bought 75% of a company called Peel Energy Carbon Capture. Which, unlike RWE, happens to have made not just the government short-list. It also just happens to be the bookies' favourite to be the winning CCS proposal. As they say, if you can't beat them, then you just have to join them.

Cost of imcompetence

The late Professor Roland Levinsky was a pioneering immunologist, and vice-chancellor of the University of Plymouth. He died because, in atrocious weather conditions, he walked into a live 11,000 volt power cable left dangling across a footpath near Wembury, Devon.
It was not as if the cable owners, Western Power Distribution (WPD), did not know about their insecure high-voltage cable. The company had been contacted several times by concerned people who had seen the cable hanging loose.

But instead of logging the problem as "dangerous", the company call centre instead listed it as just "miscellaneous". So the power was never turned off. And an engineer despatched to fix the fault was diverted elsewhere.

And the cost to WPD for its incompetence, which took the life of a distinguished academic? The paltry total of £270,000. Including legal costs. In a world where electricity companies are walking off with billions worth of unearned, windfall profits, such judicial generosity makes me despair.

Electrical distribution and motor control has a major role to play in today's industry. The systems that control it are usually referred to as motor control centres (MCCs), distribution or switchboards. Darryl Wells-Pope from Rittal explains

The construction of the enclosure is divided into a number of many different sizes of compartments arranged in rows and columns with each compartment door opening separately. These compartments contain electrical devices, which are then connected to copper busbars that power motors or distribute electricity as a distribution or switchboard.
Every compartment within the MCC, distribution or switchboard will normally house a circuit breaker and/or a motor starter normally side by side with sufficient space left over for control, power transformer and a relay. As modifications are inevitable, the compartments need to modular and available in various sizes that can accommodate different sized parts.
When compartments contain circuit breakers, the compartment door should have a handle through it to act as a means of disconnecting the power from the equipment; without opening the door. This will also allow each compartment to be shut down separately without interfering with the other processes. 

With modular MCCs, distribution or switchboards it is essential a level of separation is achieved and these forms of separation extend from ‘Form 1', which is based on a traditional open ‘cabinet' type MCC construction to the extremity of ‘Form 4b Type 7' where all starters or feeders are separated from each other - even the control terminals. In such solutions it is advisable that incoming cables can be brought into large cable chambers, with aperture sizes of up to 400mm wide, providing greater manoeuvrability for the onsite contractors and, therefore, quicker and easier installation.

Type testing in low voltage switchgear is increasingly becoming an issue of prime importance worldwide. Type tested panels in accordance with IEC 60439 Part 1 assure a high level of personal protection as well as system protection. However, one important thing to remember is to ensure all plastic materials used for the busbar supports are self-extinguishing in accordance with UL 94-VO. With such type tests, more safety is assured through heat dissipation and comprehensive short circuit resistance testing. When type tested along with various manufacturers' protective devices, MCCs offer even more flexibility of system permutations.

With MCCs or distribution boards, it is paramount that systems are totally flexible in their makeup and that busbar mounting can take place either in the roof area, the rear or mounted into the base/floor area. Such options allow for all eventualities, and offer a wider scope to cater for any electrical application, which may be required.

The design of any MCC, distribution or switchboard can be time consuming, not only does the front ‘general arrangement' require organising to make use of the valuable space, but the internal components require careful planning in order to make sure fine details such as mounting plates and busbars are included. By utilising a specialised engineering software package, designers specifying and designing MCCs can now produce drawings and parts lists within minutes. If the right software is chosen it should also allow modifications and additions, which may be required at a later date, to be easily incorporated, be able to specify the individual component parts, which allows for a quick and effortless placement of the MCC order, and allow completed drawings and parts lists to be exported into various software packages.

As so many projects are now expected to take place with a fast turnaround, when considering the self-build option it is essential the instructions are clear so the mechanical assembly can take place quickly and easily. What happens if any of the side panels are damaged during transit? Are they easy to replace? Can they be replaced?  These are questions that could cause a problem if the system is not of a modular design. With modular MCCs these issues don't tend to exist as all external panels can quickly and easily replaced, with the added bonus that any earthing cables conventionally required to be replaced can be eradicated due to ‘self-earthing' panels.

With any purchase of a motor control or distribution board it is important to consider the future use of the equipment. Although it may be suitable for today's business requirements, will it be able to cope with tomorrow's demands?  Whether the MCC can be easily extended is therefore something that needs to be considered. If it is to be extended it would be advisable to choose an MCC where the individual enclosure units can be easily bayed in the future. Consideration also needs to be given to the busbar extensions; can they be achieved easily with standard products? Are the products available quickly so the build is not delayed? And what about the compartment sizes? Can these be accommodated easily into an existing structure? Are special parts required? Do doors have to be especially manufactured or are they available off the shelf?  All of the above elements are paramount when selecting an MCC.

Any motor control centre, distribution board or electrical switchboard needn't be a complex structure if all the elements are considered, are easily and readily available and can be expanded as and when required.

Now in its third successful year, the latest in a series of regional exhibitions and conferences, sponsored by DuPont, will take place at Sandown Park, Esher, Surrey on the 24 and 25 February 2009. The event combines a seminar programme, organised by the British Safety Council, with an exhibition supported by the industry's major manufacturers and service providers

One of the most popular elements of Health and Safety 09 - South is its free seminar programme  which for the first time will this year be organised by the new official educational partner, the British Safety Council. Elements which the organisation has said it will concentrate on in regards to the seminar programme include focusing upon ‘health' as well as safety. As Nina Wrightson, Chairman of the BSC says "With the epidemiology of health being a less straight forward issue than safety, as exposure is not as easy to predict as it takes place over the long-term, it is often ignored and we intend to tackle this problem."
The educational programme takes place on both days of the event and seminar highlights on the first day, 24 February 2009, include Corporate Manslaughter/Homicide - The Impact, by Kevin Bridges of the law firm Pinsent Masons LLP. This seminar will introduce the Act and the new statutory offence of corporate manslaughter/homicide for those that are unfamiliar with its content and its anticipated impact on corporate and personal liability. Bridges will also look at how the Sentencing Advisory Panel has suggested that those convicted under the act (which came into force on 6 April 2008) should face a substantive fine - between 2.5 and 10% of their annual turnover.

Also taking place on the first day is Asbestos - The Hidden Killer presented by Stephanie Beach of the Health and Safety Executive. Beach's presentation will provide an update on current asbestos issues and recent initiatives including a summary of the HSE's recent, national, media campaign designed to raise awareness amongst tradesmen of the risk of exposure to the substantial amounts of asbestos still contained in many buildings. 
Seminars on the second day of the event, 25 February 2009, include Working at Height by David Thomas of William Hare, the structural engineering company. David will cover all aspects of safety when working at heights, setting out the simple hierarchy for managing and selecting equipment for work at height and outlining some of the fundamental measures required for a safe system of work as required by The Work at Height Regulations 2005 that apply to all work at height where there is a risk of a fall liable to cause personal injury.
As well as the busy educational schedule, more than 100 exhibitors are represented in the continually expanding exhibition area. Personal Protective Equipment (PPE) is an area which is well supported with the show's main sponsor being DuPont, with Ansell Healthcare Europe and Aearo Technologies as event partners. Other PPE suppliers such as BM Polyco and Marigold Industrial also have stands and the breadth of PPE covered includes everything from specialist protective clothing and gloves, to eye wear, ear plugs, high-visibility garments and more.

For those interested in working at height solutions, helping maintain safety and compliance in this area requires specialist equipment and advice which at Health and Safety 09 - South is available from the likes of A-Plant, Scafftag and Pammenter & Petrie.

Another element of the event which is provided free by event partner Principal People is the fire safety demonstration. Here, fire safety professionals give regular demonstrations throughout the two days about how visitors should deal with certain types of fire from the classic chip pan blaze to more complex fires. The team will be demonstrating the use of extinguishers and inviting visitors to bring a blaze under control with hand held extinguishers.

Health and Safety 09 - South also provides visitors with a the opportunity to talk to key industry bodies, professional and trade associations such as the Health & Safety Executive, the Asbestos Control and Abatement Division (ACAD) and the Chartered Institute of Environmental Health (CIEH) and IOSH all of who are exhibiting. For a full list of exhibitors visit: www.healthandsafetyevents.co.uk

Registering for the event or a seminar is free. However, visitors are advised to do so in advance to guarantee a place. Registration is via: www.healthandsafetyevents.co.uk or for those without internet access registration can be completed by calling the exhibition helpline on 0870 4866816. 

Two new white papers from Rockwell Automation reveal how progressive manufacturers are focusing on safety automation solutions to keep their people safe, their machines working and their bottom lines robust. The papers credit this focus to the adoption of a ‘holistic approach to safety' and ‘Providing the value of safety', which emphasise global standards, innovative technologies, trained personnel and ongoing risk assessment, all working together

"A Holistic Approach to Safety Automation" highlights the differences between the manufacturing industry's historical approach of separating safety solutions from the automation system, and today's integrated functional approach to safety. It also outlines the inherent benefits this direction offers, namely minimised risk and increased productivity.

"By integrating safety functions into their overall automation strategy platform, manufacturers can create a safer working environment for employees and reduce the risk of an incident that could have a negative environmental impact. It also improves manufacturing processes that optimise productivity and key performance indicators, such as overall equipment effectiveness, ultimately leading to increased profits," said Craig Resnick, research director, ARC Advisory Group. "When manufacturers adopt this holistic approach to safety, they are leveraging state-of-the-art technology to help protect their people, as well as improving their company's global competitiveness."
A fundamental shift in two essential and related areas has helped make this new functional approach to safety possible. The first is major developments in safeguarding and control technologies - most notably the advent of new microprocessor-based technologies in lieu of electromechanical or hard-wired control. The second is the evolution of global safety standards to allow these new electronic technologies to be incorporated into industrial safety systems.
The increased popularity of proactive risk analysis is also helping to propel the growth of this holistic approach, according to the paper. The objective of the safety system is to help protect people by making processes and machines safer without decreasing productivity. Manufacturers that conduct risk assessments are several steps closer to achieving all of the above - and in so doing, they help reduce risk and the costs associated with it.
"The holistic approach to safety is a best practice that ARC hopes even more manufacturers adopt," Resnick said. "Manufacturers should challenge their automation suppliers to provide innovative safety solutions and services to support their quests to operate safer, while simultaneously increasing productivity and profitability. Rockwell Automation appears to have met this challenge with their integrated safety solution offerings."
‘Providing the value of safety' outlines the long-term financial benefits manufacturers can reap by integrating comprehensive machine safety programmes into their workplaces as a form of insurance against potential risks.
 Functional safety protects workers by reducing incidents but also reduces the associated costs. These include insurance premiums, claims administration fees, workers' compensation claims, risk management department costs (salary, travel, fringe benefits, and so on), legal fees, and other related costs such as government fees, assessments and consultants.
It benefits users by cutting costs without reducing safety. It provides a high safety/failure ratio so that users can maximise both production and safety. 

Functional safety is the part of the overall safety implementation that depends on the correct functioning of the process or equipment in response to operational safety inputs. It relates to the physical operation of a machine or process. In other words, functional safety equals the confidence in the ability of the safety-related control system to perform its function over a specified time period.

The name ‘functional safety' is often associated only with programmable safety systems, but this is a misconception. It covers a range of devices, such as interlocks, light curtains, safety relays, safety PLCs, safety contactors and safety drives that are interconnected to form a safety system.

Using functional safety and its applicable standards requires the availability of data such as the probability of dangerous failure per hour (PFHd) or mean time to dangerous failure (MTTFd). In this way, the user can calculate the reliability of the safety system. This should not be regarded as an absolute and certain value but more as an indicative and relative quantification that can prevent the use of unsuitable equipment.

Functional safety falls under the umbrella of the risk reduction process which involves the following steps: 
- Eliminate problems by design using inherently safe design concepts. 
- Safeguarding and protective measures with hard guarding and safety devices. 
- Complimentary safety measures including personal protective equipment (PPE). 
- Safe working practice achieved with procedures, training and supervision.
Functional safety addresses the safeguarding portion of the risk reduction process. When users implement integrated safety by designing systems so that safety and environmental considerations are fundamental elements, they include functional safety measures as part of the safety system.

When designing equipment and associated control systems, a hazard analysis will help determine whether functional safety is necessary to ensure adequate protection against each significant hazard. If so, then users can integrate functional safety into the machine design requirements, implementation and validation.

A hazard analysis identifies what has to be done to avoid hazardous events associated with the operation and maintenance of the machinery. In addition, a risk assessment gives the safety integrity required of the safety system for the risk to be acceptable. 
As safety becomes more and more important in today's world, it makes sense for systems to be fully integrated into the factory environment.  The fact that it provides other significant benefits along the way is a real bonus.

The white papers "A Holistic Approach to Safety" and "Providing the Value of Safety" are both available at: http://www.rockwellautomation.com/solutions/safety/

 

It's easy to assume the substation on your site belongs to the power utility, but are you absolutely sure? If you get it wrong, says Damon Mount of Megger, and you're unlucky enough to suffer a transformer fault, you could find yourself landed with a bill for tens or even hundreds of thousands of pounds

In the substation, the power transformers are probably the most expensive items. And that's not the worst of it - the delivery time for a replacement transformer is typically months - or even years for the largest types. The direct and indirect costs associated with a transformer failure can, therefore, be enormous.

But there's surely no need for concern. All of the power transformers on your site are the responsibility of your energy supplier, aren't they? It may be a very good idea to check again. In a surprisingly large percentage of installations, the power transformers belong to the owner of the premises, and not to the power utility.

Of course, there's still no reason to worry, because transformer failures will certainly be covered by insurance, won't they? The answer is possibly not. Because of the huge costs involved, insurers are understandably cautious about making payouts relating to transformer faults and failures. If there is a claim, they will certainly ask for evidence to show the transformer has been regularly tested and maintained.

Since many companies are not even aware they are responsible for the power transformers on their sites, it's not too much of a surprise there are a lot of transformers that most certainly don't get the regular attention they need.

This is a special concern with the many transformers currently in use that have long exceeded their design lives. Although they may apparently still be working well, it is inevitable some of the materials used in their construction - in particular the insulating materials - will have started to deteriorate.

If an unmaintained transformer fails, whether it is old or new, it's perfectly possible that the insurers will contest the claim or refuse to pay. Let's take a look at what needs to be done to avoid this potentially devastating situation.

The first and most obvious step is for maintenance departments to check which of the transformers on their site are their responsibility. The next step is to implement a regular testing programme for these transformers.

But what form should the testing take? There are, of course, many types of conventional tests that can be applied to power transformers to check, for instance, the performance of the tap changers or the windings.

This means to build up a reasonably complete picture of the transformer's condition, a whole battery of tests is needed, which will take a considerable time to perform. During this time, the transformer will be out of service, which can be very inconvenient.

There are, however, two tests that between them can provide a wealth of information, not only about the presence of faults but also, in many cases, their type and location. These tests are sweep frequency response analysis (SFRA) and frequency domain spectroscopy (FDS).

Electrically, a transformer is made up of multiple capacitances, inductances and resistances. It is, in effect, a very complex circuit that produces a unique ‘fingerprint' when test signals are injected over a range of frequencies and the results plotted as a curve. In particular, the capacitances in the transformer are affected by the distance between conductors.
Movement of the windings, which can be caused by electrical overloads, mechanical shocks or simply by ageing will, therefore, alter the capacitances and change the shape of the frequency response curve.

The SFRA test technique for transformers is based on comparisons between measured curves, which allow variations to be detected. An SFRA test involves multiple sweeps and reveals whether the mechanical or electrical integrity of the transformer has been compromised.

SFRA tests are used to capture a ‘fingerprint' reference curve for each winding when the transformer is new or when it is known to be in good condition. These curves are subsequently used as the basis for comparisons during maintenance or when problems are suspected.

The best way to use SFRA testing is to take regular measurements on the same transformer over a period time, and to compare the results. However, it is also possible to use type-based comparisons between transformers with the same design. Finally, a construction-based comparison can be used in some circumstances, when comparing measurements between windings in the same transformer.

A single SFRA test can detect winding problems that would otherwise require multiple tests with various kinds of test equipment, as well as problems that cannot be detected at all by tests of other kinds.

As a general guide, magnetisation and other problems relating to the core alter the shape of the SFRA curve at the lowest frequencies, up to around 10 kHz. Medium frequencies, from 10 kHz to 100 kHz represent axial or radial movements in the windings, and high frequencies above 100 kHz correspond to problems involving the cables from the windings to bushings and tap changers. In modern SFRA test sets, built-in analytical tools simplify comparisons between curves.

While SFRA tests provide a lot of information about the condition of a transformer, they do not give an accurate indication of the presence of contaminants - in particular water - in the transformer insulation. Standard tests, such as the widely used Karl Fischer test, are, of course, available for accurately assessing the moisture content of transformer oil, but this is not the whole story.

In fact, it is usual for a much greater percentage of the moisture in a transformer to be held in solid insulation such as paper than is held in the oil. To further complicate matters, the moisture moves between the solid insulants and the oil in a way that is influenced by many factors including, in particular, temperature. 

Measuring the moisture content of the oil may not, therefore, provide dependable information about the moisture content of the transformer's solid insulation. This is a serious concern, as moisture in the insulation significantly accelerates the ageing process in transformers and, in addition, it can cause bubbles between windings that lead to sudden catastrophic failures.

To establish the moisture content in the transformer, the second of the tests mentioned earlier - frequency domain spectroscopy (FDS) - can be used. Initially, this may sound a lot like SFRA, as it involves measuring transformer characteristics at over a range of frequencies. This time, however, it's the dielectric properties of the insulation (capacitance, loss and power factor) that are measured over a range of frequencies, typically from one millihertz to one kilohertz.

These are, in essence, the same dielectric tests that are often carried out at power frequency, but testing at a single frequency provides far less information than is revealed by FDS testing. Unlike spot-frequency testing, FDS can, for example, reliably distinguish between a transformer that is dry but has bad oil, and one that is wet but has good oil. In the first case, the oil needs refurbishing or replacing; in the second the transformer only needs drying out.

FDS testing also has other benefits - it can be performed at any temperature, and the test can be completed quickly. Software can be used to calculate the water content in percentage terms, and modern FDS test sets typically provide accurate and detailed results in less than 20 minutes.

As we have seen, regular testing using the SFRA and FDS test techniques provides a reliable insight into the condition of power transformers, but how can this information best be used by the transformer owner?

A short-circuit fault on the transformer may cause unseen damage inside, and a damaged transformer put back into service could fail catastrophically. An SFRA test can be done before re-energising and compared to a reference trace taken while the transformer was in good working order. If the two traces match, nothing has changed and the transformer can be safely returned to service. Carrying out this test takes less than an hour, reducing outage time and saving money.

Ageing, mechanical damage and moisture content can be seen as a change in the frequency response of the transformer over time and may indicate that remedial action, such as drying out the transformer, is needed to guard against future failures. In other cases, it may show that the transformer is inevitably coming to the end of its useful life, but even then the information is invaluable.

In this situation, it may be possible, for example, to minimise the load on the transformer so it can continue in service until a replacement is obtained. And even in the worst case, there is at least a warning that failure is imminent, which can allow time for contingency plans to be made and put into place.

There is also another very valuable aspect of regular testing, which we touched on earlier. Insurance companies are more likely to honour a claim for failure of a power transformer that's been regularly tested and properly maintained so as to remedy any issues identified by the tests. Such a transformer is, of course, less likely to fail, but if it does there is at least the consolation that the insurers will foot the bill!

Even for those who are aware of their responsibilities in looking after power transformers, regular testing may appear as something of a burden. However, tests with modern instruments can be performed quickly and easily, and they yield dependable informative results. And, if the test regime eliminates just one unforeseen transformer failure that would otherwise have occurred, the effort involved in testing and the cost of the instruments used will have been repaid many times over.