Features

Variable speed drives bring great advantages in controlling motors but care needs to be taken to match the characteristics of the drive to the motor to ensure the combination is a winning one. Geoff Brown, drive applications consultant for ABB investigates


Of the approximately 10m motors installed in UK industry, only some 3% are controlled by variable speed drives. Despite the huge energy savings to be gained, often in excess of 50%, many companies are still not making use of variable speed drives to run their motors.
Yet, process operators cannot simply connect a drive to any old motor and expect huge energy savings overnight or even a successful motor and drive match.
To minimize the risk of selected motor failing, users need to understand the required operating and environmental characteristics of the application. Motors have to cope with all sorts of environments, from high ambient temperatures, to being immersed in sewage, to operating in dust or gas hazards.
Special designs exist for all of these cases and the user must ensure he follows the motor manufacturer’s instructions. Getting all the help you can from motor and drive manufacturers is also a good idea in general; their experience with motors and drives will help find the most compatible motor and drive combination. Many will have local service representatives who can assist with setting up the drive. Users installing their own drives need to read up about the issues that exist when connecting AC motors and drives.
Drives and their effects on motors
Variable speed drives come in standard voltage ratings, which must be chosen to match your line voltage. In general, the lower the voltage, the easier it is on the motor.
The high switching rates of inverter power devices can place a rain of high switching voltage pulses at the motor terminals, which will cause an electrical stress on the windings, which is partly dependent on the length of the cable connecting the inverter to the motor. The drive manufacturer will usually advise on the maximum practical cable lengths between 15m and 300m depending on the power rating. In some cases long cable runs may also require additional drive components such as du/dt filters. Long cable runs can also lead to EMC issues.
Because a higher carrier frequency means more frequent pulses, a useful feature of the drive is an adjustable carrier frequency. Lower carrier frequencies place lower stress on the motor insulation system and reduce the incidence of damage due to bearing currents. However, higher carrier frequencies have a positive effect on reducing motor noise levels. Some switching strategies such as direct torque control have no fixed carrier frequency, which can also help, while ensuring a low noise spectrum.
Frequency converters with non-sinusoidal current can also cause additional losses in the motor and an increase in motor losses of up to 15% was not uncommon in early PWM inverter designs, which translates into an overall reduction in motor efficiency of up to 1%.
Modern inverter designs still increase motor losses, beyond those of a true sinusoidal supply, but in practice the effect is less than that caused by connecting to the supply network.
Major factors causing an apparent reduction in output with modern drives is the fact that the output voltage is lower than the input voltage, due mainly to the presence of chokes and other components used to limit harmonics, and the improved switching patterns in the inverter. The reduction in voltage can often be compensated by using a low harmonic “active rectifier” drive solution.
Choosing a motor for
drive operation
Given these points, how do you go about choosing a suitable drive for a motor? Firstly, always choose a good quality motor. High quality materials will extend the life of a motor, as well as improve efficiency. Look for thinner core plates giving lower iron losses, good slot fill giving improved stator performance, good bearings reducing rolling resistance. Reduced losses make for smaller fans, cutting noise and windage losses.
Another important quality factor is the level of insulation of the windings. Voltage stress acting on microscopic air bubbles in the winding varnish can cause ionization flash-over, known as a partial discharge, breaking down the insulation. Different insulation materials can withstand different levels known as the partial discharge inception voltage (PDIV), so you need to make sure the insulation level is adequate. Standard motors commonly have a PDIV in the region of 1350 to 1600V. A higher withstand voltage is better in variable speed drive applications. Unfortunately as yet there is no common visible classification on a motor nameplate, the use of Class B, or F or H materials does not in itself confer a specific PDIV withstand level.
Inverters also have common mode voltages in their outputs, which can give rise to induced voltages in the rotor, and if the path is not blocked can give rise to circulating currents, which can destroy bearings. This problem is solved by breaking the circuit by using insulated bearings.
Choose the right combination for the environment
A particular concern is the use of variable speed drives to power motors in hazardous areas. The main sources of risk are high surface temperature and sparks in either the winding or the bearings. This can result in increased temperature rises and higher voltage stresses on the motor insulation. These increase when self-cooled motors are used, as the speed of the cooling fan is reduced along with the motor speed.
These factors can combine to create a source powerful enough to ignite an explosion. The best way to reduce this risk is to choose a combined Atex package, which gives end users the assurance that the motor and drive combination is optimised for their application.
Note that the application of a drive with an existing, pre Atex motor is at the owners risk, and possible only in a Zone 2 area. In any case the product certification is the responsibility of the motor manufacturer.
This practice of supplying matched drive and motor pairs is a growing trend and one that progressive vendors have adopted to help cut users’ workload to a minimum.
Choose high efficiency
The efficiency of the motor is always a major factor in the choice. Although a VSD will bring system efficiency gains, it will not compensate for a poor or inefficient motor. Always use the highest efficiency motor possible. Ideally, the motor should have a good efficiency across the load range.
Motor power plays a major part because AC motors work at their peak efficiency over a limited range of their power output. Modern EFF1 electric motors usually produce peak efficiency at around 75 per cent of rated load. By contrast, older designs often have peak efficiency in a very narrow band around full load.
This is important in energy saving installations because the object of a drive is to vary the speed of the load, especially with centrifugal fans or pumps. The time spent running at full load will therefore normally be limited to emergency situations, such as extracting smoke in the event of a fire.
A new high efficiency EFF1 motor rated at 90kW with 95.2% efficiency, will cost around £5,900 and will use electricity costing around £37,250 per year, but will save nearly £9,000 compared to a standard efficiency EFF3 motor with 93% efficiency, over a 10-year service life. For companies operating large industrial complexes with many motor driven machines, such savings can mean tens of thousands of pounds, and tonnes of CO2 emissions annually.
Although an existing motor already in place can usually be used with a drive, it may not be known how well the motor has been treated and higher efficiency may be gained by using a new motor.
Choose the right speed profile
It is important when designing a system to consider the motor as a source of torque. Torque equates both power and speed, and with variable speed it is the torque profile which is of importance.
The two most common profiles are variable torque and constant torque. The first is used for centrifugal fans and pumps while the second is used for conveyors, extruders, positive displacement pumps, and similar loads.
Variable torque loads are the easiest applications for motors and drives because load power is governed by the cube of the shaft rpm for centrifugal loads acting with little static head.
It is also worth considering most load machinery is designed for sale in both 50 Hz locations such as Europe, and 60 Hz locations such as the US. Due to this the best efficiency is often between 50 Hz and 60 Hz nominal speeds, i.e. between 1500 and 1800 r/min. A variable speed drive allows this to be exploited. The freedom to select the output shaft speed can also be used to advantage to eliminate inefficiencies in belt drives.
Constant torque can pose problems because in order to maintain a constant torque at low speeds, the motor needs to be supplied with a relatively constant current throughout its speed range. This mode of operation will continually produce more heat, which will need to be dissipated at low speeds.
The current ratings of the inverter must also match the motor’s current requirements both at full load and during acceleration. The drive’s current rating and its suitability for the motor needs to be checked with the motor manufacturer, especially on motors operating below 30Hz and whenever acceleration torque is critical.

Is the worldwide emphasis on the conservation of energy and raw materials actually leading to a better-lit environment?


According to Lou Bedocs three ‘drivers’ will heavily impact on future lighting practice: energy efficiency and the impending European Energy Performance of Buildings Directive (EPBD); environmental directives over and above those we have today (RoHS and WEEE), and eco-design in its many parts in the Ecodesign requirements for Energy-Using Products Directive (EuP). “The biggest impacts will be from environmental and sustainable developments,” he says. “This is all about efficient design, raw materials, recycling, waste management and take back. The WEEE directive will be implemented on 1st July, and the EuP directive later this year will lead to new materials, practices and tasks.”

Bedocs is concerned about energy efficiency. Not its necessity, but the repercussions it could have on loss of lighting comfort and quality, because people will be tempted to meet efficiency criteria at the expense of reduced comfort. A classic example is the local authority that is planning to achieve the energy efficiency targets by simply switching off the streetlights. “Our biggest task in future years will be defending our hard fought lighting needs in this environmental/energy constraining world And it’s going to be important, because if the rate of increase in energy costs continues at 10 per cent a year then obviously we need more and more efficient and reliable electric lighting solutions or we will have to change our way of working and way of life because daylight is only available at certain times.”

According to Bedocs, the answer is not to shut everything down, but to campaign for efficient use of energy rather than reduction, and second, rather than being frivolous about the criteria, to focus on appropriateness. “This will change the outlook in lighting scheme design.” Task-orientated lighting requires different optics, different light-package sizes, distributions and, above all, a different philosophy in application design. “Interestingly, we have moved from local to generalised lighting over the past 100 years and now we’re moving back.”

Bedocs argues lighting is the single most important aspect of the environment because of its immediate impact on people. Some 80% of the signals our brain processes are received through our eyes. It is now known there is an extra detector in our head that receives signals via the eye and controls our body clock. “Clearly people, wherever they are, need good lighting for visibility and the right light for wellness. Furthermore, the responsiveness to the space and people’s reactions must not be overlooked, which is why I believe in Thorn’s PEC – Performance, Efficiency and Comfort programme so strongly,” he says.

“We have achieved the task of visibility through adequate illumination and we have the knowledge to balance the brightness in the space. Our next step needs to be to provide a sustainable stimulating visual environment with effective controls that will satisfy our physiological and psychological needs at work, at play or even when driving home.”

Lou Bedocs is lighting applications director at Thorn Lighting, based in Spennymoor, County Durham.

Power quality measurement is still a relatively new and quickly evolving field. Whereas basic electrical measurements like RMS voltage and current were defined long ago, many power quality parameters have not been previously defined, forcing manufacturers to develop their own algorithms.

There are now hundreds of manufacturers around the world with unique measurement methodologies. With so much variability between instruments, technicians must often spend time trying to understand the instrument’s capabilities and measurement algorithms instead of concentrating on the quality of the power itself.
The IEC 61000-4-30 CLASS A standard defines the measurement methods for each power quality parameter to obtain reliable, repeatable and comparable results. It also defines the accuracy, bandwidth, and minimum set of parameters. Going forward, manufacturers can begin designing to Class A standards, giving technicians a level playing field to choose from and increasing their measurement accuracy, reliability, and efficiency on the job.
IEC 6100-4-30 Class A standardises measurements of:
• Power frequency
• Supply voltage magnitude
• Flicker, harmonics, and inter-harmonics (by reference)
• Dips/sags and swells
• Interruptions
• Supply voltage unbalance
• Mains signalling
• Rapid voltage changes.
Examples of Class A requirements:
• Measurement uncertainty is set at 0.1% of declared input voltage. Low cost power quality measurement systems with uncertainties greater than 1% can erroneously detect dips at -9% when the threshold is set at -10%. With a Class A certified instrument, a technician can confidently classify events with internationally accepted uncertainty. This is important when verifying compliance to regulations or comparing results between instruments or parties.
Dips, swells and interruptions must be measured on a full cycle and updated every half cycle, enabling the instrument to combine the high resolution of half-cycle sampled data points with the accuracy of full-cycle RMS calculations.
• Aggregation windows – A power quality instrument compresses acquired data at specified periods which are called aggregation windows. A Class A instrument must provide data in the following aggregation windows:
- 10/12 cycle (200ms) at 50/60Hz, the interval time varies with actual frequency
- 150/180 cycles (3s) at 50/60Hz, the interval time varies with actual frequency
Harmonics must be measured with 200ms intervals according to the new standard, IEC 61000-4-7 / 2002. The old standard allowed 320ms intervals which cannot be synchronised with the 200ms aggregation windows of other Class A measurements.
Using 200ms intervals allows harmonic calculations to be synchronous to all the other values like RMS, THD, and unbalance.
The Harmonics FFT algorithm is specified exactly such that all Class A instruments will arrive at the same harmonic magnitudes. The FFT methodology allows for infinite algorithms that can result in vastly different harmonic magnitudes. By standardising on 5Hz bins and summing the harmonics and inter-harmonics according to specific rules, Class A instruments will be consistent and comparable.
• External time synchronisation is required to achieve accurate timestamps, enabling accurate correlation of data between different instruments. Accuracy is specified with ±20 ms for 50Hz and ± 16.7ms for 60Hz instruments.
• 10 min interval sync to clock
• 2 h interval sync to clock.
Latest product developments
There have been a number of significant introductions to the market in the past 12 months of power quality analysers offering compliance with IEC 61000-4-30 CLASS A. These new products include both handheld devices and those designed for leaving in a fixed location for a time period set by the user. They will log a large number of parameters at user chosen time intervals for later analysis by a PC. Thus there is a choice of products, offering different capabilities, from which a technician can choose the most appropriate tool for the job.
These new tools are designed for ease-of-use to uncover intermittent and hard-to-find power quality issues. Suitable handheld analysers will provide on-screen display of trends and captured events even while background recording continues. Some can be used to analyse disturbances, to validate incoming power compliance, for capacity verification before adding loads, and for energy and power quality assessment before and after improvements. The best tools provide powerful reporting software to enable rapid assessment of the quality of power at the service entrance, a substation or at the load according to EN50160 standards. The software can quickly analyse trends, create statistical summaries and generate detailed graphs and tables.

The transmission and distribution business has seen a significant shift in technology over the last quarter century with the decline in oil and air insulated switchgear in favour of the newer vacuum and sulphur hexafluoride (SF6) technologies says Philip Dingle, utility segment manager at Eaton.


SF6 is unchallenged for transmission voltages but for distribution systems from 3kV to 38kV vacuum circuit-breakers have become the dominant technology (See Fig. 1)
However, vacuum interrupters are frequently used in gas insulated switchgear (GIS), which uses the greenhouse gas SF6 as an insulant. Despite worldwide concern over the environmental effects of SF6, manufacturers continue to promote the GIS concept for ring main units and packaged substations in the face of technically sound solid-insulated alternatives.
In terms of size and cost there is little to choose between the two circuit interruption technologies at distribution voltages. At one time solid insulation tended to be more bulky than gas but advances in technology have overcome this objection. Both vacuum and SF6 offer good load switching and short-circuit protection capabilities but vacuum interruption excels under the more onerous short-circuit duties and offers long life under frequent switching duty.
Vacuum interruption
The first vacuum interruptors were introduced 40 years ago and, since then, have proved remarkably reliable. Modern units retain their vacuum for at least 20 years, thereby exceeding the mechanical life of the circuit-breakers of which they form a part. Operation is maintenance-free, eliminating the need for regular inspection and costly leak monitoring equipment.
Performance is excellent over a wide range of applications including transformer secondary protection, short-line fault switching, capacitor and motor switching. The rated a.c. power frequency withstand voltage is typically two to four times normal operating voltage and lightning impulse withstand voltage voltage is four to 12 times operating voltage.
Vacuum interruptors are environmentally benign. They do not contain greenhouse gases, or present a health risk due to decomposition products caused by arcing. No special measures are needed to protect the environment from the results of leakage or at the end of life. The constituent materials can be recovered safely and recycled.
Solid insulation
Historically, one of the reasons for using SF6 gas insulation with vacuum insulators was size – solid insulation resulted in much larger units. This is no longer the case. The use of modern potting compounds such as polyurethane and epoxy to encase the vacuum interruptor, together with a contoured profile similar to the sheds used on overhead line insulators, has made it possible to increase the basic insulation level (BIL) of the vacuum interruptor to the same order as GIS.
Solid insulation means there are no greenhouse gases involved and there is no need for special gas monitoring systems and other precautions to protect personnel from the risk of leakage. The switchgear can be installed inside buildings with confidence there is no danger of a build-up of heavier-than-air gas.
Anybody who has been involved with the disposal problems created by the past use of asbestos, polychlorinated biphenyls (PCBs) or chlorofluorocarbons (CFCs) should take warning. The current use of SF6 gas in switchgear could be creating a similar legacy for industry and utilities in twenty or thirty years’ time. The very fact literature on SF6 technology devotes so much space to defending its environmental reputation should be enough to sound warning bells.
SF6 and global warming
Sulphur hexafluoride does not occur in nature. At normal temperatures it is a stable, inert gas – harmless to people and animals. However, it is heavier than air so precautions are necessary to avoid the possibility of high concentrations in confined spaces.
The principal concern is that SF6 is a potent greenhouse gas (See Table 1). The United Nations Framework Convention on Climate Change in Kyoto in December 1997 identified a basket of six major greenhouse gases:
• Carbon dioxide (CO2)
• Nitrous oxide (N2O)
• Methane (CH4)
• Chlorinated fluorocarbons (CFCs)
• Hydrated fluorcarbons (HFCs)
• Sulphur Hexafluoride (SF6)
The signatories agreed to restrict emissions of these gases to specified amounts and, furthermore, to reduce overall emissions by at least 5.2% below 1990 levels in the commitment period 2008 to 2012.
The European Climate Change Programme has set out proposals to enable the European Community to meet its Kyoto Protocol targets for fluorinated greenhouse gases, including SF6. The quantities of these gases are measured in equivalent tonnes of carbon dioxide. At 1995 it estimated the total emissions of SF6 gas as 65.2 tonnes, of which electrical switchgear contributed five tonnes.
While the concentration of SF6 may be low compared with some other greenhouse gases, SF6 has a global warming potential (GWP) 23,000 times that of CO2 and an atmospheric lifetime estimated at up to 3200 years compared with 50-200 years for CO2. The continuous build-up of SF6 in the environment therefore represents a serious long-term threat.
Furthermore, recent research has revealed a new, highly active greenhouse gas, SF5CF3 that is thought to be a product of the breakdown of SF6. Although it occurs in relatively small concentrations, its contribution per molecule to the greenhouse effect is much greater than any previously known greenhouse gas.
A report by the Department for Environment, Food and Rural Affairs (Defra) gives 1995 emissions of greenhouse gases in the UK, expressed in equivalent tonnes of CO2 as shown in Table 2. It estimated that total use of SF6 over the previous decade had remained roughly constant at 160 tonnes, equivalent to 1,200,000 tonnes of CO2 per year. Four main uses for SF6 were identified:-
• Electrical installations
• Electronics
• Magnesium smelting
• Training shoes
In switchgear, leakage may occur at the mechanical and electrical seals and even within the pressure monitoring equipment itself. Consequently, regular monitoring is necessary and procedures should be in place to ensure that monitoring takes place regularly but also that appropriate steps are taken if it reveals evidence of leakage.
Serious concerns also centre on the disposal of the SF6 at the end of its useful life. SF6 is manufactured in industrialised countries under carefully-monitored conditions. It is used in enclosed conditions with every effort taken to minimise the risk of leakage. But SF6 switchgear is being sold and installed worldwide. What guarantees are there for responsible disposal in 20-30 years’ time?
The United Kingdom is committed to reducing emissions by 12.5% from 1990 levels by 2008-2012. Other countries have already taken steps to deal with problems created by the use of SF6 in switchgear including Denmark where its use as an insulating medium in new circuit-breakers was prohibited from January 1 2002.
In Germany the following steps have been taken:
• Manufacturers guarantee a minimum leakage rate of approximately 0.5% a year
• All gas-filled enclosures are continuously monitored to detect leaks
• Used SF6 is either purified and reused in a closed system or re-use directly
• SF6 manufacturers guarantee to take back used gas for re-use or disposal by environmentally compatible means.
• All personnel handling SF6 receive regular information and training
• Only properly qualified staff carry out maintenance work
• SF6 producers keep records of quantities produced and equipment manufacturers and users keep records of gas consumption and inventories.
SF6 under operating and fault conditions
While it is stable at room temperature, SF6 breaks down into toxic substances on combustion, at high temperature, or when subjected to arcing. In the event of a major short-circuit that the system cannot handle, SF6 gas and these toxic products of combustion will be released into the atmosphere. Even under normal operating conditions, whenever an arc is suppressed, there will be toxic residues within the enclosure. This calls for special precautions when dismantling at the end of life.
At temperatures above 300°C SF6 starts to decompose, forming free sulphur and fluor ions which combine with hydrogen and oxygen ions in the air to form a number of dangerous products including hydrogen fluoride (HF) an extremely corrosive fuming liquid, thionyl fluoride (SOF2) a very stable and poisonous gas, and sulphur tetrafluoride (SF4) a poisonous gas that combines with water to form HF and SOF2. Among these latter effects, SF4 reacts with moisture in the eye to form hydrogen fluoride, which has a strong etching effect on the cornea. HF also impairs the lungs. A number of other toxic substances are also produced.
During arc interruption, these same decomposition products are produced and, in addition, metal fluorides, mostly in the form of dust. Special measures are necessary when handling this dust. Only skilled and well-trained personnel should carry out maintenance and other work. Protective clothing should be worn, including tight-fitting gloves, goggles and masks to prevent skin contact. Special measures are also necessary to ensure that dust does not come into contact with the surrounding environment. The problems of decommissioning at the end of life are comparable with those associated with PCBs in transformers.
If an internal fault should occur in gas insulated switchgear, the enclosure may burn through or the arcing energy may cause a rise in the temperature and pressure in the enclosure leading to bursting of the enclosure or opening of a pressure relief valve. As a result of any of these events, the surrounding environment will be filled rapidly with the toxic and aggressive products of decomposition. This could present a major risk with GIS substations or ring main units situated on street corners or in commercial or industrial buildings.
Conclusion
At high voltage there is little choice today but to use SF6 switchgear for circuit interruption and steps can be taken to minimise the risk of decomposition products presenting a danger to the public. Furthermore the number of installations is relatively low so utilities can support the small number of trained personnel needed to handle high voltage SF6 products.
At medium voltage, the large number of products in service make it impractical to maintain the staffing levels needed to look after equipment. The availability of compact vacuum interrupters which generally offer superior electrical characteristics, together with compact solid insulation techniques, make it practically, economically and environmentally preferable to use solid-insulated vacuum switchgear.

For further information on the consequences of using SF6 gas see www.greenswitching.com

How will the new British Standard, BSEN 62305 Protection Against Lightning effect you? Mike Henshaw, managing director of Omega Red, summarises the key requirements of the new standard.


There are now hundreds of manufacturers around the world with unique measurement methodologies. With so much variability between instruments, technicians must often spend time trying to understand the instrument’s capabilities and measurement algorithms instead of concentrating on the quality of the power itself.
The new Standard will run in parallel with existing standard for a transitional period and will eventually replace the existing Standard (BS6651:1999) at the end of August 2008.
There are four parts to the new Standard covering General Principles, Risk Management, Physical Damage to Structures and Life Hazard and finally Electrical and Electronic Systems Within Structures.
There are four separate risks that can be addressed depending upon the clients requirements:

• Risk of loss of human life
• Risk of loss of service to the public
• Risk of loss of cultural heritage
• Risk of loss of economic value

The starting point is to establish which risk the client wishes to protect against. Risk 1 is addressed under the existing Standard, Risk 2 is only partially addressed under the existing standard and then only in an informative appendix and not a formal part of the standard. Risk 3 and Risk 4 are considered for the first time within the new Standard.
A risk assessment must be undertaken for each of the risks the client wishes to address in order to determine what level of protection is required, if any, and what protection measures need to be applied in order to reduce the risk to a tolerable level. This is a new practice.
The risk assessments require certain information in addition to that already required under the current standard:

One of the most popular shows on TV at the moment is The Apprentice, in which contestants compete to win a £100,000-a-year job working for ‘straight-talking’ (ie. rude) Amstrad boss Sir Alan Sugar. Indeed, the show has been so popular it’s started to attract contestants from every walk of business, not just the sort of venal salespeople who’d sell their granny’s soul to the devil to meet their monthly target. But if any Open Circuit readers are foolhardy enough to consider applying for the next series, what do you need to succeed? Open Circuit offers some tips and advice…

The concept of partnership to improve working relationships and performance up and down the supply chain has been used successfully for a number of years. However, when National Grid, the electricity transmission network owner for England and Wales, decided to deliver a substantial part of its investment into the network through a series of regionally focused partnerships, the new rules of engagement precipitated a new way of working. Hans Van Veelan, managing director of Systems for Areva T&D in the UK and a member of the Alliance supervisory board and Geoff Singleton, Alliance manager for National Grid discuss how this collaborative approach, adopted by National Grid, will allow the various stakeholders throughout the supply chain to work more closely than ever before, delivering the programme to the high levels of quality and safety.


National Grid identified a number of key issues, the first and most important of which was to ensure continual improvement of health and safety. The second was the level of available expertise. While there is global competition for the supply of switchgear, transformers and the application of new technologies, there is a huge shortage of suitably skilled and qualified people in the UK’s electricity industry.
The Alliance approach
In order to manage these issues, National Grid offered a number of regionally based framework contracts to major international players over a five year term. These contracts work on the basis of target costing, involving all the partners sharing the pain or gain of achieving the target for actual cost. The key to the success of this new working approach is to demand the strongest levels of collaboration between all parties and to drive it by aligning their needs.
Areva T&D was one of many companies who expressed an interest. As a result Areva T&D joined with Mott MacDonald and Skanska to form a joint venture company (AMS JV) which entered into a selection process to become an Alliance partner for National Grid in one of the four substation areas – the North, Central, South East and South West.
Collaboration is king!
The selection process was multi-faceted, based not only on the technical and project management expertise, but also with great emphasis placed on the cultural fit of the partners, their behaviour and ability to work collaboratively.
The AMS JV team demonstrated exactly the type of collaborative behaviour National Grid sought. When combined with the in-depth technical knowledge and experience, the AMS JV was the perfect choice for the technically demanding South-East area and in October 2006 the AMS JV Alliance was confirmed as National Grid’s preferred partner.
The make-up of the Alliance shows the depth of collaboration possible across the partners. The Alliance management team is headed up by a senior National Grid manager who reports to a joint supervisory board made up of AMS JV and National Grid personnel. Regardless of employer the best person for the job has been chosen to fill each role. For everybody this has been a leap of faith with an interesting combination of different working relationships. The dynamics of the organisation have changed for everybody, where bosses have become clients and clients have become subordinates – suffice to say this presents interesting cultural challenges which are being actively addressed.
The collaborative approach and culture is driven across all four substation Alliances, and National Grid will assess the performance of the approach by measuring the success of their overall capital works programme for England and Wales. Therefore a significant proportion of the AMS JV’s incentive payments are reliant on the performances of other Alliances. All four substation Alliances must deliver their programmes safely, to time and to cost otherwise none of the area partners will receive their additional incentive payments. It therefore follows that if another area Alliance is in danger of missing its target, there is an incentive for the AMS JV to help them. Almost overnight, players who were competitors in the selection process have now become aligned to the common objectives of the Alliance approach.
What does the future hold for the Alliance?
The four Alliances will focus on substation development and construction. The work will also be required to connect new infrastructure, such as wind farms and other new electricity generation plant and enhancing and replacing existing assets to ensure the continued safe and reliable operation of the electricity network.
The key to the success of the partnership for National Grid and the Alliance partners is firstly, having the belief in the success of the Alliances. All of the partners have to adapt their behaviours and ensure that there is alignment of vision, values, objectives and behaviours. Finally and most importantly there has to be a solid commitment to raising the safety standard – this can be done by providing the right focus on safety which will be developed right from the start of the project, ensuring there are no accidents in any of the projects.
National Grid will benefit from forming this Alliance as it creates an opportunity for the best partners available in today’s market to come together – partners that can deliver a world class service and set new benchmarks in the execution of National Grid’s capital expenditure programme.
AMS JV’s involvement in the Alliance also brings important benefits. It allows Areva T&D as an organisation and the AMS JV as a group of companies, to be able to secure resources and to plan into the long term. With this collaborative approach the JV can now have a five year window against which it can plan and organise itself. Furthermore, the philosophy of the gain and pain principle is another key benefit - all partners, by working together and by sharing objectives and optimising their processes in the way that they work, will allow for gains to be made in the project for the benefit of everybody.
National Grid is expecting to spend over £2.5 billion through this mechanism over the next five years. The AMS JV is at the start of a long and exciting journey and the next step is for the JV to move into a central location which is almost complete. It’s important that it starts to look and feel like a single Alliance as it moves forward into the mobilisation stage. This secure and long term commitment will enable AREVA T&D to plan, manage and harness all necessary resources and capacity to set a new benchmark in the delivery of electricity transmission substation solutions.
By ensuring the partners embrace the Alliance approach with its common vision, set of values, goals and objectives, National Grid is confident it can maintain the safe and reliable operation of the high voltage network by replacing assets and by connecting new infrastructure to meet the growing demand for electricity.

Sean Jordan, product marketing manager at Schneider Electric provides insight into the growth potential for residential network cabling and explains how installers can best tap into it.


Residential structured network cabling has been around for some time – albeit largely restricted to home computing and entertainment. The concept of refrigerators talking to microwave ovens, while programming the DVD machine is some way from practicality. But, while this vision of the smart home is yet to become a viable commercial market of its own accord, useable aspects of technology are emerging all the time.
Indeed, far from being just a fad, technology is becoming more affordable and accessible, and growth in intelligent home controls is accelerating.
The new build sector remains the sector where smart homes are showing the greatest take off and where most immediate future growth will come from. This makes sense when one considers that setting up a smart home in a retrofit environment can unavoidably involve upheaval to the fabric of the building.
Manufacturers and installers alike should therefore look to property developers for residential cabling business. Fortunately, with the housing market slowing down, developers are keener than ever to add functionality and perceived value to their homes. There is a burgeoning consumer demand for more intelligent places to live and it can only be a matter of time before home buyers demand, for example, internet connectivity around the home. Selling homes with this technology allows developers to increase the saleability of a property, as well as increase, or at least retain, the value of the real estate.
Changing lifestyles
Home networking and automation systems have evolved to meet the requirements of modern lifestyles. With more and more people working from home and school children and students undertaking internet based study projects, demand for home office capability is created. It is becoming increasingly the case that families want to run computer networks to various rooms, all linked by a hidden network.
Another prime motivator for networked homes comes from the desire for flexible multi-room entertainment. The configurations of home networking systems are already plentiful and afford the possibility of distributing audio, video, voice, the internet and other media to be shared via a prewired cabled highway. Common outlets at the user interface allow inherent flexibility in room and system usage.
The security and safety aspects of smart homes prove most attractive to families. Intelligent home control systems are able to perform highly practical functions such as detecting gas leaks and alerting the homeowners in a range of useful ways. By integrating alarm sensors with other electrical services in this way, they can communicate remotely and, in case of leakage or other hazardous conditions, shut down automatically.
Highly intelligent systems can perform complex tasks such as sophisticated security surveillance. Integrating devices and appliances means everything can be controlled remotely. At the touch of a button, users can control lighting, curtain closing and opening and so forth. Lights and appliances can also be turned off remotely using mobile telephony – a safety and energy saving benefit.
Energy management
While the occupiers of a dwelling are understandably seduced by entertainment and security, installers can deliver beneficial savings through controlling energy consuming devices. The relatively simple expedient of automatically switching lights on or off by demand can save a fortune from electricity bills.
The future prospects
Smart homes do not transform our lives, but they can dramatically enhance them. They are building a momentum and as more builders incorporate smart home systems, people will come to expect a fully networked or automated home. Within a few years, we will no more expect to have to ask about the provision of installed networks in a new home than we currently question the inclusion of socket outlets or running water.

In a series of question and answer surgeries Geoff Brown, drives applications consultant at ABB, addresses some commonly asked variable speed drive (VSD) questions. The series supports a library of literature that covers the technical aspects of VSDs, how they are used and what their benefits are.
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Q: What are the potential problems of using drives in hazardous areas?

A: When it comes to hazardous area use, usually only the motor and driven load will be in the hazardous area, as the ventilation requirements for a variable speed drive severely limits the practicality of installation in the hazardous area itself.
One major area of concern is the extra losses that a variable speed drive potentially creates inside the motor, because of the voltage pulse based waveform it produces compared to the 50 Hz industrial network.
This may increase the temperature rise and reduced speed which may significantly reduce cooling, hence the risk of explosion. For this reason, hazardous area motors intended for variable speed drive applications will normally be fitted with thermistors or similar devices to monitor temperatures, and may well be fitted with a second nameplate giving the inverter fed output limit.
The drive can also be the source of other undesirable side-effects, which can include reduced motor insulation life, electromagnetic interference and bearing currents. These are effects that can be prevented and for hazardous area duty, care in such prevention is essential.
The ATEX directive requires the drive system – including motors, sensors, cabling, filters etc – to be treated as a unit. The documentary evidence of compliance is the motor manufacturers Declaration of Conformity. Matching your own motor/drive combination can be both time-consuming and expensive as it may require third party approval. The best way to reduce risk is to choose a combined ATEX approved motor and drive package. This gives end users the assurance that the combination is optimised for their application.

One of the biggest trends in today’s modern manufacturing environment is the move towards open and fully conversant automation systems. And without a shadow of doubt, one of the biggest enablers – spurring on this growing trend – has been the introduction of Ethernet into the industrial environment says Paul Brooks of Rockwell Automation.


Its introduction has had a profound impact on industry. With both plant control and office data capabilities, it offers manufacturers a host of benefits including easier integration of shop-floor to top-floor systems and the chance to use a single network infrastructure for several different functions. But can Ethernet really be all things to all people?
Too often it is argued off-the-shelf commercial Ethernet and IP solutions lack the degree of determinism and predictability required for industrial control. To overcome these perceived shortcomings, several Ethernet or Ethernet based systems have been developed for industrial use. One – EtherNet/IP – offers the industrial optimisation of a specialised control network with the openness and flexibility of standard Ethernet, taking advantage of today’s Ethernet technology without resorting to modified switches, silicon or stacks.
The decision to put Ethernet on the factory floor should not be taken just because it works, instead it must be because there is a business case to add automation to the growing long list of services that are currently being carried over the existing infrastructure. Increasingly the question being asked is “What is the business case for keeping the automation services separate?”
Rockwell Automation, one supplier of the EtherNet/IP devices and solutions, takes potential users and those on the cusp of making a migration decision through a simple checklist of factors that must be considered to ensure a successful installation.
Step 1: Understand the system requirements
This is the first and most obvious step as, without an understanding of what you actually require and, more importantly, what you want it to do, the installation could either be under or over specified or, indeed, not actually be suitable for your application.
At system environment level it is important to gauge what type of plant floor control is needed and how it would integrate into an existing or planned IT network. Security is another important issue as data can be distributed far further than was historically possible. Companies must take this into consideration when designing the system. The ability to future proof the system to a greater or lesser extent must also be considered, with expandability being at the top of the list.
Performance is another major system issue. The amount of data being carried over the network and how fast it changes can have a big impact on its architecture. With Ethernet, this is not just limited to automation data, but all of the data needed to manage a business. And, with this in mind, infrastructure also plays a large role. Users must not only consider the media being used to transfer all of this information but also hardware and software factors such as switches, routers and firewalls.
Step 2: Learn the system environment
Only by learning the system environment can you get an idea of the levels of complexity. The primary question to ask is: Will your automation system be integrated (free exchange of all types of data), connected (exchange of automation only data) or isolated (no exchange of information) from the IT system? Only by asking this question can you make judgements on the benefits that you will get from, and the level of complexity of, the potential system.
Step 3: Make IT Aware
Automation applications create a great deal of traffic with I/O control data – traffic that can impact the rest of the enterprise if IT isn’t expecting it. Good network design and implementation will resolve all of these issues but IT departments can’t take these steps if they don’t know what is happening on the factory floor. This gives you the opportunity to address other internal issues that may also arise: Who owns the network? Who is responsible for maintenance? Who assigns IP addresses? IT departments have significant value to add resolving these issues when involved early enough in the process.
Step 4: Segment networks properly
To benefit from optimum system performance, it is important to undertake proper traffic segmentation. Not only will it simplify network management but it also maximises backbone or control network availability. It is also possible to deal with security issues at this level. This does not mean factory floor and enterprise networks can’t be fully integrated - segmentation can be achieved by two means; either a physical segment can be used, such as a switch, or logical segments can be created using a virtual local area network (VLAN) or IP Subnets.
Step 5: Thou Shall not use hubs
Hubs or repeaters can allow data collisions – a particularly unattractive feature for control networks; this is why switches and routers are more attractive propositions. A switch will not only eliminate the possibility of collisions but it will also segment traffic within an IP Subnet while routers help segment networks and traffic.
Step 6: Select the switch with the proper features
Not all switches are created equal, and with switches at the heart of the network it is important to specify them correctly. The application is, of course, the first consideration. What is the switch expected to deal with? Is it suited to the operating environment? What type of data will it be handling (commercial or industrial)? It is also important at this stage to define what is required, what is recommended and any elements that may make up part of a ‘wish list’.
There are a number of features that are prerequisites for switches used with EtherNet/IP, these include: full-duplex capability on all ports; IGMP snooping, to constrain multicast traffic only to ports associated with a particular IP multicast group; and port mirroring, the ability to direct a duplicate of the frames being transmitted on one port to another port for troubleshooting. Switches that fit the bill are available from a number of Rockwell Automation Encompass partners.
Step 7: Select and install the right media
A chain is only as strong as its weakest link – for this reason you must ensure suitable media is used for the transmission of data. Users have a choice of two media, each of which has its own advantages depending on the application.
CAT 5e and 6 copper cables and connectors are recommended for industrial applications. UTP (unshielded twisted pair) is generally recommended, while STP (shielded twisted pair) is recommended for metal conduits and noisy environment. It is important to ground one end only.
Fibre optics are good for noise immunity and long distances when connecting switches together. Single-mode fibre optic cable, through which only one mode will propagate, is more resistant to attenuation and can be used in significantly longer cable runs, while multi-mode fibre optic cable gives high bandwidth at high speeds over medium distances, and is a more of a general-purpose media.
Step 8: Understand end-device limitations
It is unlikely traffic over a 100Mbps or 1Gbps infrastructure will be the cause of any bottlenecks. With high bandwidth networks like Ethernet, the limitation on system performance is almost always due to the processing power of end devices. It is for this reason that end device vendors must provide performance information and calculation rules for their devices and users must factor all devices into the system calculations – not all end devices offer the same capabilities.
Step 9: Be aware of potential security issues
By sharing a network, information can be spread further and so security could become an issue. But, if it is managed and controlled from the outset, there is no reason why an Ethernet network should be any less secure than any fieldbus is today. In fact, use of standard Ethernet is an important tool to make business critical data and systems far more secure! And, because it is using standard Ethernet, there are a wide variety of consultants qualified to help get it right.
Some common practices include: logical separation of the IT/Corporate LAN from the automation network; limit access to the automation system only to those with a legitimate need using strict access policies; the implementation of plant floor security processes, policies and procedures; and the incorporation of IT security technology to enforce access policies.
Step 10: Don’t hesitate to get help
Companies like Rockwell Automation have a considerable depth of expertise and knowledge when it comes to automation installations and the associated networking hardware, software and media. Organisations investigating the possibility of a move over the industrialised Ethernet should take advantage of this depth of knowledge, as it is more than likely that their questions have already been answered.
Remember, EtherNet IP is not difficult – it’s just different!

An important final note – while Ethernet is very versatile and can perform some functions that dedicated device level networks cannot, it does not offer all the features of a purpose-built control network. So, for specific control applications requiring the robustness of ControlNet or the scalability of DeviceNet, an industrial Ethernet is unlikely to fit the bill and, as a result, Rockwell Automation remains committed to the development and support of products using these networks.

For more information visit:
www.ab.com/networks/ethernet/next-step.html
www.ab.com/networks/ethernet/pdf/UnmanagedSwitches_07252005.pdf

Bernard Johnson, programme controller for the ABB Mowlem Southern Region Power Supply Upgrade (SRPU) team, explains how detailed planning, coordination, collabora-tive working and an uncompromising approach to health and safety helped make the project so successful that in the end nobody noticed it!

In 2003, Network Rail embarked on its three-year Southern Region Power Upgrade (SRPU) programme to support the introduction of 2000 new, more comfortable carriages. Thanks to features such as central door locking, CCTV and air conditioning, the Bombardier Class 375/376 Electrostar and Siemens Class 450 Desiros trains draw around 23 per cent more power than the old rolling stock from the 750V traction power supply system – the reason for the upgrade.
With 3,196 miles of track, Southern Region is the UK’s largest private operator of an electrical distribution system. And the upgrade is believed to be the largest DC project of its type undertaken anywhere in the world.
Kent region
ABB in consortium with Mowlem Railways was one of four regional contractors appointed initially by Network Rail, and the consortium was awarded the Kent region – extending from Ramsgate on the coast through to Cannon Street substation in central London. Between 2003 and 2006 the consortium carried out around £80 million of project work including the construction or upgrading of 27 substations and 17 feeders and installing around 100 panels of ABB ZX1.2 gas insulated MV switchgear and 25km of 33kV cable.
Working on one of the world’s busiest rail networks presented a whole raft of challenges and constraints as all site deliveries, possessions and outages had to be planned down to the finest detail. This was especially important because, while the SRPU project was vital for Network Rail’s future plans, its over-riding need was of course to keep the trains running on a day to day basis, so potential disruption and delays had to be kept to an absolute minimum.
It was clear that communication and coordination at all stages, from definition, through design, tender for the individual work packages to execution, would be the key to the success of this project. So it was decided to take the unusual step of co-locating the consortium team alongside the client team in Network Rail’s project office in central London. This ensured that right from there start there was no ‘us and them’, but rather a partnership that enabled problems to be solved before they became issues.
Possessions
Management of ‘possessions’ – the windows of opportunity when access was available to work on individual sites – was a core element handled by specific team members. This was particularly challenging as six months is a normal period of notice for a possession, while on some of the busiest routes access was only available at Christmas, so they had to be planned 12 months ahead. Added to this, Network Rail’s operational requirements sometimes meant that planned possessions had to be cancelled at the last moment, calling for the team to think on its feet to reorganize work programmes to maintain the overall project momentum.
Much of the site work was carried out at night and weekends. The team also became particularly adept at ‘piggybacking’ on access to sites that had already been granted to Network Rail’s own team for routine track maintenance. Of course, with two different teams on site working with different objectives, careful planning was needed to ensure there was no clash of priorities.
Deliveries
Hand in hand with the planning of possessions, the delivery of equipment to the sites was planned with military precision. A great deal of effort went into making this a ‘non-rail’ project where possible, using road access rather than rail to deliver equipment, although there were a number of ‘rail-locked’ sites with no road access. On some sites, the limited access called for specialized rail-mounted cranes to manoeuvre heavy equipment into position. Again this required long-term planning as there are only three such cranes in the UK.
In order to keep on-site work and costs down, the project made substantial use of containerized substations, which were fitted out off site. They are housed in robust, long-lasting, stainless steel enclosures that should last for 40 years.
Health and safety
An uncompromising approach to creating a safe working environment was paramount throughout the project, with the emphasis on minimizing potential risk to site operatives. This was reflected in a remarkable safety record. All work on the infrastructure was undertaken with the Rimini plan system, which is used to make sure the safest system of work is used when ‘on the line’. In addition a safety coach was kitted out, known affectionately as ‘Thunderbird 3’. This was despatched to the various sites to show videos and provide information and handouts about the specific safety issues that the working gangs might encounter on that site.
Innovative team approach
Mid-way through the project a substantial work package was started for the north Kent ring of substations. Because of the way the substations in the ring are linked together it was not possible to take two out of service at the same time without disrupting the network. So an innovative approach was adopted by constituting a separate, dedicated planning team with representatives from all interested parties. The team was led by Network Rail, and as well as the consortium it also included the Scada team, the network controller, the outage planner and representatives from the team working on the inner London region of the SRPU, since our work could also impinge on their area. By meeting on a weekly basis the 12-strong planning team ensured that the north Kent ring work package proceeded without a hitch.
ZX1.2 switchgear
For the SRPU project ABB used its ZX1.2 range of metal-clad gas-insulated medium voltage switchgear which has technical acceptance from ENA (the Energy Networks Association) and Network Rail for use at 33kV for ratings up to 31.5kA and 2000A.
ABB designed the ZX1.2 with a modular, plug in approach to meet the specific needs of electricity distribution network owners and operators by providing compact, flexible substation configurations that offer reliable and cost efficient switchgear solutions for single busbar applications. Key design features include laser welded stainless steel enclosures, compact modular construction and the introduction of plug-in technology which facilitates simple, controlled connections of busbar, cable, test bushings and voltage transformer, without the need for ‘on site’ gas handling equipment.
All maintenance-free live components, such as switching devices and busbars, are contained under SF6 in gas-tight enclosures, which eliminate the effects of ageing processes and environmental influences to ensure maximum operator availability and a long service life. The ZX1.2 design also offers easy cable access at the rear with generous provision for conventional control and protection devices, dedicated cable test sockets and full mechanical interlocking between the disconnector/earthing selector and the circuit breaker
Underneath the arches
The innovative side of the consortium really came to the fore in constructing a new substation in Vauxhall. Space is at a premium in this part of London and it was difficult to see where it could be placed. The consortium hit on the idea of utilising two dilapidated arches of a railway bridge to create a smart new indoor substation. As well as special cladding to make the substation watertight, ventilation and fire detection systems were installed to ensure the complete safety of the enclosed transformer.
People
The success of the SRPU project was not just down to procedures. A key aspect was the excellent people working as a team across the board - civils, engineering, project management and installation and commissioning staff, supported along the way by administration and specialist safety and possession staff.
At the peak in January 2005, there were around 140 ABB Mowlem project staff, along with many other installation, civils, cable pulling contractors and site staff.
The final verdict
By November 2005 all the new trains were in service, with not one train introduction delayed due to a lack of power, and Network Rail’s view on the overall Southern Region Power Upgrade project was – “the project so successful that in the end nobody noticed it!”

The Association of Graduate Recruiters recently claimed employers were unable to fill many graduate level jobs because new graduates, particularly in engineering and construction, were lacking in teamwork, leadership and communication skills. It’s a familiar refrain, but if you’re an employer, how do you know if potential graduate employees are up to scratch? Well, Open Circuit is here to help. Simply make any graduate job applicants sit the following quick quiz.

1. What interested you in a career in engineering in the first place?
A. I enjoy the challenge of finding practical solutions to problems and seeing tangible end results.
B. I was pretty nifty with Meccano as a kid.
C. I’ve always wanted to meet Carol Vorderman.

2. As a graduate, what is the appeal of a career in electrical engineering in particular?
A. I see it as a chance to apply the knowledge learned on my degree course, with the possibility of moving into management later in my career.
B. The degree course at the University of Didcot Parkway was the only one I could get onto with two Es at A-level.
C. I couldn’t get a job in the media.

3. As a test of your basic electrical knowledge, explain why birds can land on power lines without being electrocuted.
A. The conductivity of the power lines is thousands of times greater than that of the birds’ feet and electricity takes the path of least resistance.
B. Birds have evolved to withstand 400kV electric shocks.
C. The birds are probably wearing little rubber wellies.

4. What qualities make for a good ‘team player’?
A. Flexibility and the ability to get along with a variety of people.
B. The ability to lead hour-long, time-wasting group discussions about important issues of the day, eg. which member of Girls Aloud you’d most like to engage in a romantic relationship with. (Or, if female, the relative merits and dismerits of Johnny Depp as compared with Brad Pitt.)
C. Exceptional ‘blame shifting’ skills.

5. Which of the following statements is the best example of good business communication?
A. Customers will be able to buy all our products direct from our website as of 1 May 2007.
B. You can get all our stuff on the global interweb thingy soon!!!
C. Utilising cross-platform new media technologies, value-added client/OEM partnershipping will make a paradigm shift from the traditional retail model to direct field entry ordering systems, in a one-stop-shop total virtual warehousing solution supported by man/machine interfacing.

Results
If the answers were:
Mainly As: You have found the ideal graduate employee. They are intelligent, personable and articulate. Unfortunately, this means they’ll probably swan off to do a law conversion course in two years’ time.
Mainly Bs: You have found the archetypal average employee, neither outstanding nor useless. But nurture them, encourage them, give them the chance to shine, and they’ll be exactly the same in 15 years’ time.
Mainly Cs: Oh dear. You have found the worst kind of clueless timewaster. If you must employ them, move them directly into the lower end of middle management, away from either ‘coalface’ work or genuine decision-making, and thus where they can do least harm.