Features

With energy efficiency high on the Coalition’s agenda, we are continually seeing various initiatives put in place to control energy use, lower bills and diminish carbon emissions. The latest initiative in discussion is smart meters and how a national roll-out will encourage and direct the UK towards a greener economy.  As the Government calls upon industry experts and providers to submit proposals on how best to conduct this roll-out, Andy Slater, director at smart grid communications specialist Sensus urges the Government to consider all the variables that will contribute to a successful national roll-out

Details of the proposed roll-out of smart meters in the UK have now been revealed by the Department for Energy and Climate Change (DECC) and Ofgem. Viewing smart metering as integral to its ‘green deal’ – the policy of enabling households to reduce the amount of energy they use by improving their own energy efficiency - the government has proposed smart meters as the ideal way of increasing consumers' awareness of their energy use, giving them control over their consumption during peak times and allowing suppliers to offer innovative tariff structures, benefiting customers who reduce their energy consumption.
The Prospectus signifies a sense of determination by the government to roll-out smart meters across the country, partly motivated by the anticipated financial savings in the domestic and smaller non-domestic sectors. In the prospectus, the government points to anticipated cost savings of £17.8bn over the next 20 years, and a net benefit of £7.2bn. Furthermore, the reduction of the nation’s carbon footprint via smarter energy use will, in time, demonstrate the benefits of such an initiative.

Whilst the end results are deeply encouraging, there is a fear that this urgency to deploy smart metering systems could lead the government to unwittingly choosing a communication network that could cost the UK an additional £1.8bn if the meters fail to connect to the network, due to poor coverage. This is an issue that will be heavily dependent on the type of network technology chosen for the national roll out.

Leading industry players, including British Gas and Arqiva with BT, have already demonstrated their support for the roll-out, launching smart meter trials with different network technology. It has become clear the two technologies used in trials, cellular and long-range radio, are the two most debated options for national roll-out.

For a successful smart meter roll-out, key attributes the government needs to ensure are; A robust, dedicated network to ensure performance, security and availability to utilities, underpinned with service level agreements; A cost effective and very high first-time connection rate for meters enabling smart metering to be available universally to all, minimising second visits to homes and any additional engineering costs; a proven pathway for smart grid applications and other utilities, like water, to join in the future with minimal impact and a proven ability to cope with demand.

It is in some of these key areas other technologies, like cellular, can fall short. This also raises the issue that the government needs to begin stipulating targets for each of these variables in order to observe which network is able to meet them, thereby leading to a conscientious decision.

Meter connectivity for example is an issue that certainly requires a target, as adopting a network that fails to connect could end up costing the UK more than it aims to save. The government needs to stipulate the percentage of meters it anticipates covering by the smart meter network – a target of which should fall above 90%. Cellular provider Vodafone estimates only 70% of UK homes will have cellular coverage to their meter cupboard. This is not because of a lack of coverage but due to cellular signals not penetrating areas to where meters are actually located. Therefore if cellular is chosen as the network solution what will happen to the 30% (9million) homes that don’t have adequate cellular coverage?

When looking at other benefits for both communication technologies, it is clear that the benefits of long-range radio over cellular have not been fully appreciated. It is fundamental a robust communications network is stimulated to ensure the uninterrupted flow of information between customer and supplier. Significant effort should therefore be made to create a dedicated and cost-efficient, nationwide platform. In this instance it is too easy to assume this would be a key benefit for cellular as the network is already in place and proven to work. This would be a superficial assessment. The fact cellular is already in use for consumer mobile applications hardly assures it will be optimised for securely connecting fixed devices buried in cupboards and basements like our electricity and gas meters.

Although it’s a fairly new technology in Europe, long-range radio has proven to successfully provide high first-time meter connectivity rates and widespread coverage across urban and rural areas in North America. Experience has shown it to have a first-time connection rate to meters of greater than 95% within coverage areas - ensuring a minimal number of homes are left unconnected. Long-range radio services like FlexNet were designed from the outset solely for smart metering and grid applications which should instil some confidence into the market that it is a network that can be trusted, to serve its purpose. By offering a dedicated and secure network with universal coverage, long-range radio offers communications of a quality suitable for what should be regarded as part of the UK’s critical infrastructure. With the masts already in place the roll-out of this network would only take a matter of months.

Whichever communication network is selected for the UK, it must be the one that offers the best quality of service to consumers and business at a competitive cost. If a network type is selected which does not build and protect customer confidence with high meter connection rates and if financial savings could be jeopardised as a result of not doing this, then additional costs and delays will be experienced. Therefore, I urge the government in their consultation to consider setting targets for meters connection rates and to ensure new solutions, such as long-range radio, are fully considered.

For panel builders, using cable management solutions to identify wiring, terminal blocks and components is vital. Not only will clear identification aid future maintenance and reconfigurations, it will also offer reassurance to those responsible for health and safety. John McGee, product manager for identification and protection at HellermannTyton, looks at the cable identification solutions available and how panel builders can potentially save time and money

Cable management is an important part of panel building. Correct and clear identification offers a number of benefits, for both the short term and future use. Cable management technology has advanced significantly in recent years, meaning panel builders now have a wide range of differing solutions.  This ensures they can find the right solution to address a variety of issues.

With technologies constantly changing, panel builders will find themselves faced with new challenges. Over the next few years, those working in the panel building industry will need to change their knowledge base to account for greater integration of controls and measurement, utilisation of compact solutions and demand for environmentally-friendly measures.  Andrew Garfield from Schneider Electric discusses the solutions for the future

Despite the recession, manufacturers are still continuing to introduce new technologies to the market.  Coupled with this, the evolution and introduction of legislation is shaping businesses’ views of the future and the demands they place on suppliers including panel builders.

The increase in traffic on existing tracks combined with new high-speed rail projects means that rail traction is fast becoming an important load on electric supply grids. This in turn is focusing attention on voltage stability as well as the power quality of the surrounding grids. Rolf Grünbaum, Per Halvarsson, and Björn Thorvaldsson of ABB explain how FACTS (Flexible AC transmission systems) can enhance power quality in rail feeder systems

There are several ways to feed rail traction systems with electric power. One scheme used in many traditional electrification systems is to supply it directly using the fundamental frequency main power, ie, 50/60 Hz. The transmission or sub-transmission voltages are then directly transformed by a power transformer to the traction voltage.

A Government energy contest that will inspire the public to do likewise? Don’t make me laugh says our grumpier than usual old man

So UK Prime Minister David Cameron challenged Whitehall Ministries to compete to reduce energy consumed in their departmental headquarters during October.

Energy and Climate Change Secretary Chris Huhne originally threw down the gauntlet to government departments back in May when he declared they must reduce energy use. The October versus September competition figures are to be made public. The ultimate aim is a 10% reduction across the central government estate of some 7000 buildings in an effort to to inspire the public to reduce their energy use.

Hmmm. One of the ways in which central government is looking to save energy is by negotiating with (imposing upon?) British Gas to deploy a 'payment by results' investment performance contract with the Home Office. Another is to spend money with facilities management giants Amey to deliver energy saving solutions.

Meanwhile, the Department of Media, Culture and Sport is deploying IT virtualisation (whatever that is) technology to reduce the number of network servers it uses. Over at the Department of Energy and Climate Change a trial is to take place using ceiling tiles that store heat during the day and release it in the evening. This initiative is part of the Technology Strategy Board 'Energy Efficient Whitehall' green technology project – now there is a name to conjure with.

Only the deluded or a fool (or Jeremy Clarkson) would decry the ambition of energy consumption reduction. While I am, at times, both deluded and a fool, I would never argue with the sentiments of energy saving – it’s just that I am more concerned with the immediate priority of running out of the stuff than I am about global warming (on which the jury remains out in my view). I would also remind anyone acquiescent enough to listen, that by increasing power from nuclear sources, we also help mitigate for environmental impact.

The other thing that is making me grumpier than usual is the dichotomy government presents between price and cost in all matters including energy conservation. For example, the excellent Building Schools for the Future programme would have seen a raft of new educational buildings that are both fit for purpose and energy efficient. Yet this, along with similar schemes, has been axed. The reason given is the usual nebulous one of wastage in the design and building process (for which I’ve seen no hard evidence).

The message this promulgates, against a backdrop of sweeping cuts, is one cannot spend money (thereby improving the immediate balance sheet), but one must save money in future (without having had the means to do so other than by shedding jobs or turning off lights).

As electrical engineers and contractors will attest, there isn’t much money around right now and where projects have been able to continue, the budgets have come under increasing scrutiny. In other words, there is the strong possibility that anything that’s not statutorily required will likely be removed from the schedule. Could this include niceties such as energy metering, lighting controls and such like? I couldn’t possibly comment.

I must keep this column brief because I feel compelled to write to Southern Electric and British Gas suggesting they improve their performance or I won’t pay my bills. Similarly, I have to look up Amey’s telephone number and see what they can do about my dodgy draught excluders.

Many organisations seeking to lower their carbon footprint are tapping into solar energy using photovoltaic systems, which are highly vulnerable to lightning damage. Ian Langeveld, UK and Ireland sales manager with Wieland Electric, discusses the importance of suitable protection for these systems

As technology has become an integral part of everyday life, measures to protect our devices and the systems that serve them have also increased in importance. Indeed, in some cases, protecting these systems has become critical to the business’s ability to operate. Thus, for example, protection against the damage that can be caused by lightning strikes is now just as important for many businesses as securing their buildings against intruders.

Now, with the growing use of photovoltaic (PV) arrays to harness solar energy there is an additional area to be considered when it comes to protection strategies. And with feed-in tariffs encouraging electricity generation from renewable energy sources this is an area that will continue to grow.

There are now less than 12 months to go before machine owners and manufacturers are required to comply with the new Machine Safety Directive. Paul Considine of Wieland Electric suggests there are benefits to making the switch earlier

For the last year or so machine owners and manufacturers have had the choice of complying with the old Machine Safety Directive, based on EN 954-1, or the new Directive, in compliance with EN ISO 13849-1 or EN (IEC) 62061. Some have chosen to make the switch early, while others have opted to wait until the last minute – in this case 31st December 2011 – before adopting the new Directive.

This is the story of a remarkable product manufactured by a similarly remarkable family-run power engineering company, and how it has made significant inroads into the supply transformer market. From technology to market in under two years the Wilson e2 is now specified by leading commercial organisations and blue chip companies.

Leeds based Wilson Power Solutions (WPS) is proud to celebrate the success of its e2transformer range - the UK’s most energy efficient distribution transformer. This is the UK’s first and only super low loss amorphous distribution transformer that substantially reduces operating costs and CO2 emissions. As a result the e2 is already delivering significant energy savings to businesses committed to driving down their energy costs and radically improving their carbon footprint.

The Wilson e2 - the highly efficient transformer brand

The unique e2 is the result of pioneering technology from WPS, a company that is wholly committed to engineering excellence, product innovation and the provision of cost efficient power solutions aimed at reducing environmental impact. The cause for celebration at WPS is that the e2 is a ‘home-grown’ product borne from the collaboration of a small R&D team with an equally small R&D budget at its disposal! Using proven technology and design the Wilson e2 transformers combine amorphous metal cores with low resistance copper conductors to provide unrivalled savings in both core and copper losses.

Groundbreaking Energy Savings -Reducing operating costs by up to 15%

Since its launch just two years ago the Wilson e2 has been able to demonstrate startling
payback results on the initial investment required. The e2 provides guaranteed savings through reduced transformer losses. These savings can be accurately forecast depending on the size of the unit and typical load. For example a 1000kVA transformer at 70% load will save 28,000 kWh (~£2250) per year through loss savings and achieve payback on the additional investment in just 2.5 years. Significant additional savings can be achieved through in-built Voltage optimization capabilities where site supply Voltage is high and Voltage dependent loads are present.

Corporate endorsement
The Wilson e2 transformer is helping numerous customers including NHS hospital trusts such as Whipps Cross University Hospital, the Natural History Museum and leading supermarkets, to reduce their operating costs and lower their carbon emissions. ASDA and Tesco have already recognised the very considerable benefits that Wilson e2 transformers are delivering to their bottom line.

Daniel Travers from the Tesco Corporate Purchasing team commented: “Tesco is installing the Wilson e2 transformer into its estate as we believe it will assist us to improve our emissions target whilst helping us achieve our commercial constraints. The team at Wilson Power Solutions have shown strong technical expertise and customer service.”

The smart Voltage Optimisation solution for HV applications
11-14% kWh reduction

An additional -5% to +7.5% tapping range is built into the Wilson e2 at no extra cost. This enables the operating company to optimise voltage supply from 415V to 380V according to the needs of an individual site, wherever the incoming supply is at medium voltage. This solution avoids the need to invest in supplementary downstream voltage optimisation equipment and represents an extremely cost effective VO for HV installations with a typical reduction of 12% in kWh consumption. The transformer also integrates smoothly with current installations without the risk of disruption. Endorsing the VO capabilities of e2 for additional savings, the Hilton Hotel in Portsmouth saw a significant kWh reduction of up to 14% after replacing their transformer. Similarly, food manufacturer Cranswick bacon recorded an 11% reduction despite increased production levels.

Key features
Lowest combined transformer losses
Built to IEC76/BSEN60076 standard
Interchangeable with most existing installations
Flange heights to EA35-1
Midel or oil filled
Available for ratings from 315kVA- 3MVA
In-built Voltage Optimisation capabilities
Eligible for an interest free Energy Efficiency loan from Carbon Trust

New – the Wilson e2 plus
The new Wilson e2 plus is currently undergoing final trials and is being introduced to provide an ‘intelligent’ Voltage regulation solution where supply to site fluctuates or a constant (+/- 1.25%) output Voltage is required. e2 plus comes with an automatic voltage regulator that operates on load tap changers to provide stabilised site voltage.

Wilson Power Solutions family business

• Wilson Power Solutions is the Yorkshire-based home of family owned businesses, Power and Distribution Transformers Ltd and Richard Wilson Dencol Ltd.

• Now under the direction of the third generation of a remarkable power engineering family, this privately owned group strives to meet and exceed the highest standards of quality, client care, environmental sustainability and social responsibility.  It has a successful and growing export division.

• Passionate about the environment, Wilson Power Solutions is the first UK power engineering company to be certified Carbon Neutral in 2008.

• Leading provider of energy efficient and sustainable power distribution products and solutions:
- Wilson VO – Voltage optimisation equipment for LV applications
- Chargetec battery chargers
- Power and distribution transformers up to 150MVA
- Wilson sustainable: Re-engineered transformers and switchgear
- Buyback of redundant transformers

To share in the cost savings and environmental benefits delivered by e2 contact Wilson Power Solutions for an assessment of your company’s energy management strategy, by calling the Sales Engineering team on

+44 (0)113 271 7588
For more information about products and services visit
www.wilsonpowersolutions.co.uk

The UK government is currently looking to smart meters as one of the key initiatives to drive energy efficiency, transforming the country’s consumption of energy by enabling consumers to make informed choices regarding their energy use, lower their bills and reduce carbon emissions. Andy Slater, director at Sensus, explains

There is no legal requirement to replace aged oil filled switchgear with modern vacuum types. The fact is most switchgear, of any age, if properly maintained is both safe and reliable. oil filled switchgear has been with us a long time and has proven to work well. In which case why does there remain an imperative to upgrade oil filled equipment? There are safety, reliability and cost considerations that belie the above statements, as Tony Harris of the PBSI Group explains

Safety, reliability or cost in any combination provide a real incentive to evaluate existing switchgear in any application. In spite of the fact there is no legal requirement to modernise existing aged installations, the Health and Safety Executive, the British Standards Institute and the Institution of Engineering and Technology have all published documents relating to safety. By the same token, major users of switchgear, such as the UK’s Network Distribution Operators and the power generation industry have also highlighted the need to modernise because of the mission critical nature of their applications. Finally the rising costs of maintenance and the, often, punitive penalties for system failure have added a significant motivation for renewal.

Dealing with safety issues first and foremost, it must be reiterated that dangerous failures of switchgear are rare. Unfortunately, rather like other rare failures, such as aircraft malfunctions, the consequences can be disastrous. Similarly, we only consider within this article, the equipment itself under safe and responsible operation, rather as we would not consider human error to reflect on the fitness for purpose of any other item of equipment.

The HSE makes clear in the introduction to its excellent Electrical Switchgear and Safety – A Concise Guide for Users that: In general, switchgear has a proven record of reliability and performance. Failures are rare but, where they occur, the results may be catastrophic. Tanks may rupture and, with oil-filled switchgear, this can result in burning oil and gas clouds, causing death or serious injury and major damage to plant and buildings in the vicinity. Failures of switchgear can also result in serious financial losses.

Having stated there is no law requiring users to replace aged switchgear, it is a legal requirement to provide management systems to ensure safety and minimise the risks of injury. To comply with this obligation it is clear that switchgear must be inspected, assessed and where necessary overhauled, repaired or replaced.

This having been said, de-skilling and cost reductions in some organisations have left them without the specialised knowledge needed to properly assess the function, potential risks and remedies where equipment is involved.  Switchgear suppliers must therefore provide intelligent and conscientious assistance to users – which does not mean simply selling them some new equipment!

Let's take a look at some of the dangers specifically associated with the use of older switchgear. Among the most important are:
- Lack of knowledge – users may not have enough knowledge to be aware of the potential risks involved
- Overstressing – the switchgear may not be rated to handle present-day full load currents and fault levels
- Modifications – the manufacturer may have issued recommendations for modifications to ensure that the equipment remains safe to operate. It is essential these are implemented
- Dependent manual operating mechanisms – all switchgear currently in use must incorporate operating mechanisms that do not depend on the operator's strength and speed to make and break contacts. Any switchgear that does not meet this requirement is unfit for use
- Lack of proper maintenance – this is usually the result of oversight, but may also be due to limitations imposed by financial controllers in order to minimise shutdowns. It is important that maintenance of older switchgear takes into account the age and peculiarities of the equipment.

Addressing these issues involves implementing an effective switchgear management system. A very good starting point for this is Health and Safety Executive document HSG230 Keeping Switchgear Safe. The guidelines contained in this document define records that need to be kept and keeping these records will ensure that:
- The switchgear is not outside its managed life cycle
- The maintenance cycle and the maintenance work carried out has taken into account the age of the switchgear
- The maintenance has been fully and correctly completed
- A full maintenance history is available
- All restriction notices have been considered and, where necessary, appropriate actions have been implemented
- The Switchgear is known to fall in line with latest requirements, such as independent manual operation, anti-reflex handles
It is worth noting these records not only provide a framework for increasing the reliable and safe operation of the equipment, but also help to meet legal obligations, not least those related to ensuring that employees are protected from harm.

Safety in practice
Increasingly companies have become reluctant to operate older switchgear locally – particularly oil circuit breakers. With this in mind a minerals company recently ordered new vacuum oil replacement breakers, P&B Switchgear’s VOR-M, to replace old MV oil switchgear at its salt mining installation in Cheshire.

Vacuum retrofit breakers have been installed to replace 11kV oil breakers at a major pharmaceutical plant in Speke, Liverpool. This enables remote operation, as opposed to the local, manual, operation of the old switchgear. Not only does this ensure greater safety, but it also means switchgear can be operated without personnel having to don cumbersome arc flash protection clothing.

A major chemical company is also replacing old and obsolete air switchgear with 415V switchgear with modern compact air circuit breakers. During type testing of new retrofit circuit breakers to replace 415V circuit breakers from two well known, but now defunct, UK manufacturers, the original isolating contacts from both designs failed catastrophically under short circuit conditions. The fault level was within the rating of the equipment when supplied many years ago, indicating deterioration in performance of the contacts. Fortunately, P&B Switchgear was able to supply alternative type tested replacement isolating contacts with the circuit breakers to ensure the customer has a safe installation – this might perhaps start to ring warning bells with other switchgear users.

Reliability is key
Because diligently maintained and inspected switchgear of any age can be considered safe, a greater incentive to consider replacement or renewal of existing switchgear is often reliability. Reliability in sectors such as power generation, utilities, oil and chemical industries, transport and so forth is crucial. However, accurately assessing mean time between failures for switchgear is almost impossible. Hence, these industries often regard it as beholden upon themselves to mitigate worst case scenarios, however potentially unlikely. Many operators resort to establishing arbitrary maintenance procedures and time intervals based on their type of switchgear, age of equipment, its location and environment and so on. This usually involves high degrees of guesswork, certain assumptions and, if reliability is of paramount importance, a truncation of the service or inspection intervals. None of which is particularly efficient, but reliability trumps efficiency in such circumstances.

The main reasons for replacing switchgear are usually because the age of the equipment is causing a high level of maintenance, this in turn causing higher costs, lack of availability (reliability) and difficulty in locating obsolete spare parts. Some motives are to remove oil (safety) although some companies have elected to introduce remote operation on older switchgear as a cheaper way to improve safety by removing the need for a local operator. Safety may become a key driver for replacement in the future.

The use of the latest equipment with its inherent monitoring and reporting facilities, increases efficiency and hence reduces costs. However, in older plant, it is the reliability, rather than the automation, of the system that is the highest priority.

Reliability in practice
Most UK coal power stations were fitted with 11kV and 3.3kV air break switchgear when they were built in the 1960s. Over the past decade or so the circuit breakers have needed increased maintenance. That, coupled with the difficulty in obtaining spare parts for obsolete equipment, has led to many of the older breakers being retrofitted with P&B Switchgear vacuum circuit breakers. The overwhelming majority of these power stations have ranges of fully type tested retrofit vacuum breakers on most key circuits to increase reliability of operation. This is manifest in increased time between maintenance and in many cases, to increase the fault level to cater for additional generation being added over time. P&B designs have been type tested to well over 50kA rms, with peak making currents and DC components enhanced far above the original, or indeed, current IEC/BS requirements. Examples of this are at Ratcliffe, Cottam, Ferrybridge, Fiddlers Ferry, West Burton power stations to name a few.

The latest designs of breakers to replace oil types incorporate resin embedded vacuum interrupters and magnetic actuator operating devices for the ultimate in maintenance free, long life operation. This is especially suitable when frequent use is an important requirement, such as in process industries.

Costs are a key driver when assessing assets and running expenses. This is in greater focus even in the power generation sector, where costs have generally been less of a factor – reliability and safety ranking higher. It is understandably difficult to quantify costs and therefore economies in operating switchgear. However, the impact of greater reliability and perhaps just as significantly the ability to monitor and control the installations have made substantial savings that greatly offset the price of renewal of entire switchgear panels or the upgrading of them using the latest relay technologies.

Cost justification in practice
Replacing switchgear is never high on the list of capital requirements unless the previously discussed factors are important. As mentioned earlier there are guides issued by the likes of the HSE which assist users in the selection process of replace, refurbish or retrofit, but the cost of the options is usually a significant factor.

Often a straight forward approach is to simply remove the old switchboard and install a complete new one. This delivers a new installation compliant with the latest standards, but it is not usually the most cost effective option, even when the protection is to be replaced at the same time. Depending on the size and type of substation, replacing the old with new switchgear is likely to result in extra time and costs for building work, further costs and, of course, potential risk in disturbing or replacing cables that result in longer project timescales on site. It also requires a complete shutdown. Since in many cases the switchgear fixed portion is in good enough condition, these issues can be avoided with a circuit breaker retrofit option, even if the decision is to upgrade  to modern protection relays.

Some companies consider the initial cost of a suite of retrofit breakers and argue this amounts to perhaps70% of the price of a new switchboard. However, when one takes into account the additional costs described earlier, the overall installed price for the retrofit option is typically nearer to 50%, with less disruption and reduced downtime. The case for organisations to select reliable partners has become increasingly important.

Power transformers are a critical, capital-intensive asset for the utility industry.  As an asset manager reviewing the life expectancy of a transformer, or a substation operator responsible for determining the loading capabilities of a transformer, you should be concerned with the water content in your transformer.

One of the most important ageing indicators of transformers is the water content in the solid part of the insulation (paper, pressboard).  Accurate diagnostic tools for determining the health of your transformers is critical. The OMICRON DIRANA is a unique and efficient device which determines the water content in the solid insulation.

Moisture entering in to oil-paper insulation can cause three dangerous effects in transformers: it decreases the dielectric withstand strength, accelerates cellulose ageing (de-polymerization) and causes the emission of gas bubbles at high temperatures.

Water in transformers comes from four sources: residual water after drying, water from cellulose and oil ageing, water through leaky seals or repairs, and water due to breathing.  Therefore, even in the case of a non-breathing transformer the moisture can reach a critical level.

The DIRANA measures the dielectric response of solid insulation in equipment. The dielectric response is a unique characteristic of the particular insulation system.  The increased moisture content of the insulation results in a changed dielectric model and, consequently a changed dielectric response.  By measuring the dielectric response of the equipment in a wide frequency range, the moisture content can be assessed and the insulation condition diagnosed.  For the dielectric response, the measurement is performed as a traditional ungrounded specimen test (UST), made from the high voltage winding to the low voltage winding (CHL) in a two winding transformer.  We are most concerned with the CHL test, as this is the measurement which contains the most cellulose insulation material.  The test connections and modes are the same as used in a traditional transformer insulation Tangent Delta (or power fact)test with the difference being that it is performed at a low voltage, up to 200vpp, and the test is performed at frequencies from 1 kHz to 10µHz. 

The unit combines the polarization current measurement (PDC) method in time domain with frequency domain spectroscopy (FDS) and thus significantly reduces the testing time compared to existing techniques.  Essentially, time domain measurements can be accomplished in a short time period but are limited to low frequencies. The extended measurement range of 5 kHz down to 50 µHz, allows the DIRANA to discriminate between the oil, insulation geometry and paper.  The result is independent from the moisture equilibrium.

The patented technique combines the advantages of both principles.  It acquires data in the time domain from 10 µHz to 0.1 Hz and in the frequency domain from 0.1 Hz to 5 kHz.  This reduces the measuring duration by up to 75% compared to exclusive frequency domain measurements.

DIRANA's moisture determination is based on a comparison of the transformer's dielectric response to a modelled dielectric response. A fitted algorithm compares the measured data with the modelled data and calculates the geometry data, the moisture content, as well as the oil conductivity.  The moisture assessment is based on IEC 60422. The software is very easy to use, and the user only needs to enter the oil temperature.

Aged transformer oils often have increased values of conductivity due to acids and other ageing byproducts. This can lead to incorrect water content results. The insulation model in the DIRANA's software compensates for this influence.

Excessive water content can be extremely detrimental to the life expectancy of a transformer. The Dirana provides a simple, non-intrusive method of detecting this moisture and alerting the user of the need to take action to alleviate the problem.

www.omicron.at

Tel: 01785 251 000

Cutting electrical energy use in motor-driven applications through the use of variable- speed drives (VSDs) is a well-proven method, but not everyone is getting the message. ABB takes a systematic approach to energy sustainability that provides proof of just how much can be saved

A major part of sustainable manufacturing is using energy wisely. As energy prices continue to rise, it is becoming increasingly important to make the most efficient use of energy, both as responsible companies that care about the impact on the environment and for the future profitability of the company.

Yet, many companies do not know where their biggest energy use is and have misguided ideas about how best to cut it. A survey of UK manufacturing managers revealed the most common method of reducing the electricity bill was to switch suppliers, yet as all suppliers are increasing their prices, this can only provide a minimal saving. Other managers cited increased compressor efficiency or improved factory heating. The real answer lies in looking objectively at where electricity is used most and assessing how it can be reduced cost- effectively.

The elephant in the room is electric motors when you consider 65% of the total electricity at industrial sites is consumed by electric motors driving pumps, fans and compressors to name but a few.