Features

With plastics extruders and injection moulding companies looking to reduce energy usage, minimise maintenance costs and boost productivity, the role of the direct drive torque motor is coming to the fore. Andy Parker-Bates, of Parker SSD Drives Division, explains how the technology differs from conventional motors, and explores the benefits it can bring

They’re known by many names – torque motors, direct drive motors, frameless motors – and often they are thought of as a new technology that needs to be more proven before it becomes a mainstay of industrial automation. So just what are torque motors?

First off, it’s worth making the point this is not an unproven technology. It is a new take on existing brushless servomotor technology that has been around for decades, and is amongst the most reliable technologies available. In short, a torque motor is a rotary brushless servomotor optimised for low speed operation, typically in the order of 50-500rpm. It is a direct drive solution, so there is no need for mechanical transmission elements such as gearboxes.

There are two different kinds of torque motors. There is the more traditional looking motor with frame, cooling system, terminal box and feedback sensor, and then there is a frameless motor made up of two independent elements (rotor and stator) intended to be tightly integrated into the mechanics of the application.

Typical applications for the frameless version include semiconductor manufacture and machine tools, while the framed version meets the needs of applications such as paper machines, crushers, extruders and injection moulding machines. It’s certainly not a panacea for all applications, and indeed below about 30kW it’s questionable whether there are any gains to be had over a conventional motor/gearbox combination at all. But above this, in specific applications such as plastics extruders and injection moulding machines, at a time when end users are looking to reduce operating costs, through better energy utilisation and lower maintenance requirements, torque motors can offer significant advantages.

For starters, a direct drive solution is inherently more energy efficient than a motor/gearbox combination. Modern motors can of course offer high efficiencies and gearbox design has also developed significantly leading to more efficient products. But gearbox efficiency is dependent on the load, the reduction ratio, and the number of stages. Optimum gearbox efficiency is obtained at maximum load, but efficiency decreases dramatically at light loads – down to as little as 20% in worst-case situations. And even in its most efficient load ratings a gearbox will still lose around 2% efficiency per gearing stage.

Further, the motor and gearbox need to be closely matched in order to maximise energy efficiency, and even a good motor/gearbox combination may be only 80% efficient. Additionally, traditional motor/gearbox solutions will also often require belts and pulleys as part of the drive train, further reducing efficiency.

Torque motors, by contrast, improve in efficiency at lighter loads. Thus the direct drive torque motor can easily be between 5% and 12% more efficient than a motor/gearbox combination. If we assume a typical 7% improvement, with an energy cost of €0.10 per kWh, then in 7200 hours operation per year on a 100kW extruder, €5040 will be saved in energy costs alone by switching to torque motors.

Replacing a hydraulic motor to drive the screw on an injection moulding machine, the torque motor could easily offer energy savings in excess of 20%, and deliver higher productivity and clean operation, without the need for fluid changes or the risk of fluid leakage.

We can look at maintenance costs, too. In a typical 110kW DC motor with a gearbox, maintenance can represent a cost of more than €3000 per year. How do we come to that figure? A typical year’s maintenance on a 110kW extruder, maintenance on the DC motor could account for €300 in motor revision, €150 in carbon control/change and €150 in filter maintenance. Gearbox maintenance could contribute €50 in oil draining and €250 in seals replacement, with the potential of €2500 or more in gearbox repairs. And that’s before we’ve considered the cost of downtime in terms of lost productivity.

Use of a torque motor slashes these costs, firstly because it is an inherently low maintenance technology and also because there are no additional drive train components to wear.

Also, without the need for all of these ancillary components, torque motor systems are much quicker and easier to install: having to install and align multiple motors, gearboxes, belts and pulleys on something like a plastics extruder is a process that can take days. By contrast, installing the corresponding number of torque motors can be achieved in just a few hours.
A typical plastics extrusion machine could be using multiple motors, so the savings from not having additional power transmission components quickly add up to something very significant. In a co-extrusion machine, for example, there could be up to nine motors installed in a single machine.

Torque motors also help to address specific machine requirements on co-extruders in the way that conventional motors are unable to match. For example, the screw extraction mechanism may be required from the front of the motor in some instances, but from the back of the mechanism in others. This is readily achievable with some torque motors. At the same time, torque motors with hollow motor shafts can provide extruder screw cooling through the motor, – especially important for big screws.

Torque motors are a low noise, low vibration option. The European Noise Directive 2003/10/CE sets the maximum recommended noise level exposure limits for operators in order to protect against health and safety risks, and sets a maximum noise exposure limit of 87dBA. Above 80dBA, special protective measures must be taken. In a conventional motor/gearbox set-up, just the gearbox alone can often be producing above 90dBA. The torque motor, in contrast, is an inherently quiet technology, producing below 80dBA in most cases, and therefore can play a key role in minimising overall equipment noise levels. Similarly, it is a very low vibration technology. This again contributes to reduced noise levels, but it also has reduced physical impact on the rest of the machinery – ensuring greater reliability – as well as helping to ensure a more uniform product quality.

We also have to look at the costs of downtime in the event of a power transmission failure. Plastics extruders represent some of the most demanding motor applications. Once production has started, the one thing you don’t want to be doing is halting production. The extruder is typically located at the beginning of the production line, so stopping it will call a halt to all production. Because it has to be heated, there are long ramp up times before production can begin. And when there are defects in the output, products cannot simply be recycled and disposal costs are high.

Reliability is therefore paramount. With fewer components in the power train, the direct drive solution is inherently more reliable than a typical motor/gearbox combination, and certainly much easier to replace in the event of a fault, allowing production to be restarted much more quickly.

From the machine builder’s point of view, the torque motor solution is generally much more compact than the motor/gearbox combination. The motor can also offer built-in advantages for specialist extruder manufacturers. An integrated thrust bearing can be added to support back pressure from the screw. This is a nice added feature on injection moulding machines, but is a mandatory feature on plastics extruders. Also, a screw extraction mechanism can be readily built in, making it easy to remove the screw from the extruder for routine maintenance or to allow a new production batch to be set up. And, as discussed, the screw can be cooled by water through the motor, which can be an extremely useful feature on large extruders.

Typical torque motors cover torque ranges from 1200Nm to 22,100Nm, and speeds from 50 to 500rpm depending on size. Water cooling is standard on many designs, but natural ventilation is possible with suitable derating.

With all these advantages, torque motors are steadily making inroads into the plastics extrusion and injection moulding markets. The upfront cost may be slightly higher, but the energy savings, elimination of ancillary components, reduced maintenance costs and improved productivity – not to mention the reduced noise levels – quickly allow users to recoup the premium on the purchase cost. In addition, the more compact design can lead to smaller machines, which frees up valuable floor space, potentially driving opportunities for even higher productivity.

Peter Jones, engineering manager for grid systems at ABB in the UK, explains why HVDC Light connections are set to play a key role in the development of offshore windfarms and outlines ABB’s enhanced 4th generation HVDC Light technology that offers a number of important advantages

Plans are taking shape in Europe for the construction of several very large offshore windfarms – with a total capacity of some 25 to 33 GW - many of which will be in hostile, remote locations in waters around the UK. The design, construction and operation of large-scale power plant 100 km or more out to sea requires significant design and construction skills, especially in creating efficient and reliable links to bring the power to the mainland grids.

The need is for a very robust electrical transmission system with high availability and minimal maintenance requirements that meets not only the strict national grid codes but can also withstand the harsh and sometimes very hostile offshore climate of the North Sea.

HVDC technology
For well over a century, high voltage alternating current (HVAC) was seen as the natural choice for electrical power transmission. However, the capacitance per unit length makes AC cables impractical for transmitting large amounts of power over distances greater than 50–70 km: a significant amount of reactive power is generated, and low-frequency resonances may result in instability.

While classic high voltage direct current (HVDC) technology has been commercially available since the mid 1950s, it has mainly been used for point-to-point, high-capacity bulk power transmission links over long distances or for the interconnection of asynchronous grids. Its active components are high power thyristors. A typical application is China’s 800 kV Xiangjiaba-Shanghai link, which provides the capacity to transmit 6,400 MW over a distance in excess of 2,000 km.

Over the past 13 years ABB has pioneered a new generation of HVDC based on VSC (voltage source converter) technology – HVDC Light – that uses series-connected power transistors rather than thyristor valves. It is ideal for integrating dispersed, renewable generation, especially wind power, into existing AC grids. It is also used for smart transmission and smart grids due to its great flexibility and adaptability.

The world’s first HVDC link to connect an offshore wind farm with an AC grid is the BorWin1 project. Based on HVDC Light technology, this 200 km link connects the Bard Offshore 1 wind farm located off Germany’s North Sea coast to the HVAC grid on the German mainland. This link transmits 400 MW at a DC voltage of ±150 kV and was ready for service in late 2009.

When complete, BARD Offshore 1 will consist of 80 wind generators, each with a capacity of 5 MW. These will feed their power into a 36 kV AC cable system. This voltage will then be transformed to 155 kV AC before reaching the HVDC Light converter station, located on a dedicated platform. Here the AC is converted to ±150 kV DC and fed into two 125 km sea cables, which then continue into two 75 km land cables, transmitting 400 MW power to the land-based converter station at Diele in Germany.

HVDC Light technology
HVDC Light uses IGBTs (insulated-gate bipolar transistors) connected in series to reach the desired voltage level. This technology is used for power transmission, reactive power compensation and for harmonics and flicker compensation.

HVDC Light uses PWM (Pulse Width Modulation) that enables the magnitude and phase of the AC voltage to be freely and rapidly controlled within the system design limits. This allows independent and fast control of both the active and the reactive power, while imposing low harmonic levels (even in weak grids). Normally, each station controls its reactive power contribution independently of the other station. Active power can be controlled continuously and, if needed, almost instantly switched from ‘full power export’ to ‘full power import.’ The active power flow through the HVDC Light system is balanced by one station controlling the DC voltage, while the other adjusts the transmitted power. No telecommunications are needed for power balance control.

From a system point of view, an HVDC Light converter acts as a zero-inertia motor or generator, controlling both active and reactive power. Furthermore, it does not contribute to the grid’s short-circuit power as the AC current is  controlled by the converter.

Offshore wind integration
An HVDC Light converter station’s ability to enforce an AC voltage at any arbitrary value of phase or amplitude is of great value in starting an offshore network. Initially, the offshore converter operates as a generator in frequency-control mode, creating an AC output voltage of the required amplitude and frequency. The voltage is ramped up smoothly to prevent transient over-voltages and inrush currents. Finally, the wind turbine generators are automatically connected to the offshore network as they detect the presence of the correct AC voltage for a given duration. This functionality cannot be realised with classical thyristor-based HVDC transmission, as the latter would require a strong line voltage to commutate against.

An HVDC Light connection can similarly be used for network restoration after a blackout. As a blackout occurs, the converter will automatically disconnect itself from the grid and continue to operate in ’house-load’ mode. This is possible because the converter transformer is equipped with a special auxiliary power winding for the supply of the converter station.


HVDC Light cables
In offshore windfarm applications, HVDC Light uses extruded polymer cables, which are a strong, flexible and cost-effective alternative for severe conditions and deep waters. This cable type has a copper or aluminium conductor surrounded by a polymeric insulating material, which is very strong and robust. The water sealing of the cable has a seamless layer of extruded lead and finally two layers of armouring steel wire in counter helix to provide the mechanical properties.

To see how these cables compare with conventional AC cables, consider the requirements for a 550 MW subsea connection over a distance of 75 km. For an AC scheme, three single-core 220 kV cross-linked polyethylene (XLPE) cables would be required with a copper conductor cross-section of 1600 mm2 and copper wire tensile armour. The weight of the three cables is 3x60 kg/m = 180 kg/m. However, a VSC-based HVDC link would require only two 150 kV cables with a copper conductor cross-section of 1400 mm2 and steel wire tensile armour. The weight of the two cables is 2x32 kg/m = 64 kg/m, that is around one third of the AC scheme. This weight saving reduces both the cable cost and installation cost, while the shorter total cable length (for 2 HVDC cables compared with 3 AC cables) also reduces factory production time scales.

13-year track record
The first commercial HVDC Light scheme was commissioned in Sweden in 1997. Since then 13 projects have been put into operation, with 25 converter stations and a total capacity of over 5,000 MW and more than 2,600 km of cable installed. Over this time the technology has demonstrated an availability of greater than 98%.

HVDC Light has been used for the world's longest land cable, the Murraylink (220 MW, 180 km) in Australia as well as the 105 km subsea Estlink between Finland and Estonia. It is currently being used for Eirgrid’s 500 MW East-West interconnector that will link the Irish and UK grids in 2012.

Evolving technology
The first generations of HVDC Light technology were based on a two-level PWM converter which has been continuously improved. This provides the base component in the CTL (Cascaded Two Level) converter technology now being deployed as part of our enhanced 4th generation (G4) HVDC Light Technology.

The main advantage of the enhanced HVDC Light G4 technology  is the low converter losses of around 1% (compared with 3% for the first generation) due to the low switching frequency provided by the CTL topology. The low harmonic generation also eliminates the need for AC filters and contributes to a very compact installation footprint.

HVDC Light G4 also offers additional flexibility since the maximum rating available within one module is +320 kV and 1150 MW and it is capable of being used with both cables and/or overhead lines.

Summary
HVDC Light is a technology developed over more than 13 years of operating experience for interconnections between AC grids. It offers a number of important features that can contribute to the successful development of wind power as an integral part of the generation mix. Among these are long low-loss submarine cable transmission links, the ability to cope with rapidly variable generation and black start capability.

When it comes to cable management, debates over the suitability of one solution over another are commonplace, but when it comes to the pros and cons of perforated cable tray in relation to wire mesh things can become heated. In order to get a balanced view on the subject Electrical Review spoke to Nigel Leaver, a marketing manager in Legrand’s cable management division, which manufactures and sells both products

Tracking the perforated tray versus wire mesh debate back to its origin is relatively straight forward, with it all beginning when wire mesh first squared up to perforated tray with a view to grabbing market share and establishing itself as the solution of choice.
Ever since, this battle between the new kid on the block and the traditional old master has demanded industry attention, with the two trading blows, but neither being able to deliver the telling, knock-out punch. 

As a manufacturer of both types of tray we are ideally placed to referee such a bout – providing as we do a balanced and non-biased opinion on both solutions. Unfortunately, this neutral position doesn’t mean we can resolve the debate as perforated and wire mesh tray are both perfectly acceptable solutions and both are covered by the same European standard for tray and ladder (IEC 61537).

Instead, the decision of when to use one rather than the other is very much dependent on the installation – meaning the question to ask is not, which is the best, but rather, how do I choose between them?

Round 1
One of the main benefits of wire mesh tray is that it’s said to be cheaper and quicker to install, and in many situations this is the case.

Take for example an installation in a confined space with numerous twists, turns and obstacles to cope with. In this situation wire mesh tray is cheaper and quicker to install due to the fact it is designed specifically to be configured on site without the need for factory manufactured fittings. However, this task does need to be undertaken by experienced installers so as to avoid potential problems such as sharp edges caused by poorly cut and installed fittings.

Of course, installations do vary and if we were faced with one that required numerous straight lengths then we would typically advise in favour of perforated tray. The reason being it’s generally stronger and so only needs supports every 2.0 to 2.5 metres, rather than the 1.0 to 1.5 metre intervals that wire mesh requires. Therefore, with fewer cantilever arms or trapeze hangers to fit, the installation time, and subsequently cost, is significantly reduced.

Round 2
Another differentiating factor between the two that is often picked up on is that wire mesh tray is generally installed using accessories that are made on-site, whereas perforated uses dedicated factory fittings.

Again, the debate focuses on ease of installation, and again no definitive answer can be given. As perforated tray comes with factory fittings, some may say the job of installation is far easier than it is when having to create fittings for wire mesh on-site.

On the other side of the argument, the flexibility provided by being able to create fittings on site can be invaluable – especially when you consider just how quickly these bends and fittings can now be made, and the speed with which they can be secured using clips like our Fastlok. And of course, some manufacturers do now supply factory made bends, tees and risers for wire mesh tray with the aim of tipping the balance in its favour.

Round 3
The suitability of the two types of tray in relation to different cables also needs to be considered. Both can carry power and data cabling, however, when installing power cables these need to be fitted with steel wire armour or a second sheath of PVC-U as perforated and wire mesh tray provide cable support, rather than full mechanical protection.

Following directly on from this, is the question of how cables are secured. In the majority of instances this can be achieved through the use of cable ties, but this approach becomes unsuitable when larger cables, such as 3-phase power cables, need to be carried. Then there is no choice but to secure the cables with specially manufactured cleats, which need to be fixed securely to an already rigid system.

Until very recently this was something that could only be achieved to a satisfactory level using perforated tray, but a UK cleat manufacturer has recently developed, tested and launched a wire mesh clip that provides a strong and reliable means of securing cables with high fault levels, which can be used in conjunction with heavy duty trefoil cleats – a development that allows wire mesh to compete with the traditionally stronger perforated tray on this kind of installation.  

Round 4
Finally, the availability of different finishes should also be taken into account. Wire mesh is most commonly supplied with an electro-plated finish, which is similar to the standard pre-galvanised finish of perforated tray. Both systems can also be supplied in stainless steel or hot dipped galvanised finishes for more aggressive environments. In fact, it’s only when a system is installed in an area where corrosion will be very high, that a difference between the types of finish becomes significant. In these scenarios, perforated tray can be given a thicker galvanised coating (deep galvanised) that uses special sheet steels that can provide a galvanised thickness of at least three times that normally used – a solution that gives an extended product life three times that of a standard hot dipped galvanised product and up to six times that of electro-plated wire mesh cable tray. All of which means, the more aggressive the installation environment, the more suitable perforated tray is.
 
Round 5
In terms of general usage, the rule of thumb tends to be that wire mesh tray is used in applications where the installation is in a false ceiling or cavity floor. One reason for this is that its design allows for better air circulation, thus reducing numerous potential problems caused by overheating cables. Meanwhile, in installations, which are accessible to the general public, and therefore at risk of vandalism or accidental damage, perforated tray provides greater physical protection to the cables due to the fact it’s secured with screws, which are harder to vandalise and less likely to be accidentally dislodged than the quick-fit tabs used to secure lengths of wire mesh tray.

The big fight verdict
As you can see, not only is it hard to say which of the two solutions is better, it is also difficult to provide a definitive guide as to when to opt for one over the other – and, with the strides being made in the development of wire mesh this boundary is likely to become ever more blurred. Therefore, in order to ensure that you get the best possible solution for any given installation, make sure you talk to a company that isn’t biased.

The increase in traffic on existing tracks combined with new high-speed rail projects means 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
Part one of this article appeared in electrical review October 2010 or can be viewed at www.electricalreview.co.uk

Load balancing
The traction load, with a power rating of up to 120MW, is connected between two phases. Without compensation, this load would give a negative phase sequence voltage of about 2%. To counteract this imbalance, the load balancer, an asymmetrically controlled SVC, was installed.

A load connected between two phases of a three-phase system can be made to appear symmetrical and have unity power factor – as seen from the three-phase feeding system – by applying reactive elements between the phases.

The HS1 load balancer is optimised to handle a load connected between the ‘a’ and ‘c’ phases. In accordance with load-balancing theory, to balance a purely active load, a reactor needs to be connected between the ‘a’ and ‘b’ phases and a capacitor between the ‘b’ and ‘c’ phases. The traction load has a reactive part which also needs to be balanced. Not only is the asymmetry compensated for, but the addition of a capacitor between the ‘c’ and ‘a’ phases also regulates the power factor to unity.

The load balancer is controlled to compensate for the negative phase sequence component present in the current drawn from the supergrid. Furthermore, the power factor is regulated to unity. The positive phase sequence voltage can also be controlled if the capacity is available. This depends, however, on the load balancer working point.

Capacitive compensation technology for HS1
In the latest project for HS1, ABB is implementing capacitive compensation solutions to prevent voltage drops along the 25kV catenary supply.

There are some areas of the line where the catenary voltage can drop as low as 17.5kV, causing a reduction in overall system performance. These voltage drops result from the inherent design of the isolation transformers (used to isolate between HS1’s AC traction power supply and the adjacent Network Rail DC traction power supply), located in the existing substations along the line, as they require large magnetising currents and therefore demand substantial inductive reactive power. This causes a drop in the voltage supply as seen by the train’s catenary.

A number of studies commissioned by HS1 have demonstrated a reduction in the reactive power demand from the isolation transformers will improve system performance. This will be achieved by the installation of  capacitive compensation equipment that will effectively cancel out the inductive power demand of the transformer, and hence reduce the voltage drop. ABB will design, manufacture, install and commission capacitive compensation filters in nine AC/DC compounds at strategic positions along the line.

SVC Light
With the advent of controllable semiconductor devices capable of high power handling, voltage source converters (VSCs) with ratings beyond 100MVA are now feasible. VSC and insulated gate bipolar transistor (IGBT) technologies have been brought together to create a highly dynamic and robust system with a high bandwidth known as SVC Light, for a variety of power conditioning tasks in grids and beyond. Using pulse width modulation (PWM), an AC voltage almost sinusoidal in shape can be produced without the need for harmonic filtering.

Balancing rail traction loads
With its ability to generate voltages of any amplitude and phase angle, SVC Light can fulfill the role of a load balancer. By connecting the VSC to the grid, SVC Light can be treated as a synchronous machine in which the amplitude, phase and frequency of the voltage can be independently controlled. In addition, with high frequency PWM switching, the VSC is also capable of synthesizing a negative sequence voltage.

Compared to the classical SVC based on delta-connected TCRs for the same rated power, an SVC Light with phase-wise connected valves and a common DC link can compensate a train load that is √3 (1,732) times larger. The delta-type connection is less efficient for balancing unsymmetrical active power than it is for symmetrical reactive power compensation. This difference does not exist if a phase-wise connection is used.

Two SVC Light installations are in operation in the French railway system. Both are fed from the national power grid, one at 90 kV and the other at 63kV sub-transmission levels. At both sites, SVC Light is used to dynamically balance the asymmetry between phases caused by the mode of traction feeding. In these cases, the thyristor locomotives are fed power from two phases of a three-phase grid. The locomotives generate harmonics which are then actively filtered by SVC Light.

SVC Light cost benefits
SVC Light offers not only a technically but also an economically advantageous solution. If SVC Light was not available, then to meet the requirements of imbalance, the supply network in-feed would have to be transferred from 63kV to 225kV or 400kV. This in turn would require the erection of new overhead lines as well as the upgrading of a number of substations currently supplied with 63 kV or 90 kV.

Marco Cable Management’s technical team outlines their most frequently asked installation questions…..

Marco, the UK’s largest manufacturer of Steel Wire Cable Tray, and uPVC Cable Management Company, is committed to supporting customer’s needs, enhancing the installation process through product development and customer support.

This year has seen the launch of a number of new products including the Elite Trunking range, a number of accessories and an anti-microbial protection for uPVC Trunking. To help users make the most of these latest innovations, Marco’s technical team has provided information related to some of the most commonly asked questions:

 Do you have an alternative accessory to the traditional nut and bolt fastening for Steel Wire Cable Tray? What can you do to help reduce installation time on site?

The Marco Strut Clip offers a fast fix alternative to traditional fixings. The strut clip secures the tray in place with just one turn of a screwdriver, making installation quick and simple.
Marco Quick Locks remove the need for nut and bolt assembly kits for producing bends on site, instead simply allowing any fixing to be produced by the means of just one simple clip.

What uPVC Trunking products would best suit specification for both refurbishment and new build hospital schemes?

Marco now offers an antimicrobial protection for all of its uPVC product ranges, including the new ELITE Hygieia Range. These Trunking systems are used nationwide in environments where the spread of infection must be controlled, such as hospitals, care homes, schools and laboratories.

Marco utilises silver ion technology to create a defence against 99.9% of harmful bacteria growth. This provides built in protection from, and prevents the growth of, bacteria, fungi, mildew and moulds, including MRSA, E-Coli, Salmonella, Klebsiella Pneumoniae and Streptococci.
The design of the product is not only aesthetically pleasing, but also prevents dust from settling on flat surfaces.  All fittings have been manufactured without any deep grooves or ridges to eliminate the build up of debris in hard to clean areas.

How do I ensure ROHS compliancy through the specification of products?

Marco’s products are all lead free in their make up and therefore meet ROHS compliancy, giving customers peace of mind when specifying Marco products.

Marco is committed to operating a sustainable business and has recently achieved ISO14001 accreditation, which demonstrates company wide commitment to the environment through various schemes to reduce waste, reuse material and recycle where possible.

All production is UK based reducing the ‘product miles’ and carbon footprint – the company estimate that Marco trays travel almost 400 miles less than the trays of most of its competitors.

Steve Davis of Marco Cable Management commented: “We want to be able to communicate with our customers at every level and support them in achieving their requirements through the specification and installation process. This year we have launched a podcast, re-designed the website and launched a new comprehensive brochure to showcase the Marco range and capability, giving our customers choice in terms of the information platform that suits them best.”

www.marcocableman.co.uk 

Although a standby generator’s usual state is ‘idle’, it must nevertheless start immediately on demand in the event of a mains failure. To guarantee this, it is essential to run a suitable maintenance regime that covers not only scheduled testing, inspection and repair but also emergency call out and spares holding support appropriate to the installation. Uninterruptible Power Supplies Limited’s Kevin Ashton explains how to provide this maintenance cover effectively

The first part of this article can be found in Electrical Review September 2010 or at www.electricalreview.co.uk

A standby generator typically spends nearly all of its life in preparation to supply power in the event of a power cut. The site’s uninterruptible power supply (UPS) system can handle short term mains failures or power outages. A failure that exceeds the UPS battery autonomy will not offer support to the critical load. Therefore when it is unexpectedly called upon, the generator must respond as it’s designed to, delivering the time critical power protection when needed, thus ensuring power continuity.

Generators, like all engines, will suffer from natural wear and tear and can potentially fail. So this failure is identified when the generator is most needed, i.e. during a power failure, it is vital the generator set is covered by a maintenance plan that closely matches the needs of the generator and its applications. This maintenance plan should not only cover maintenance visits, but should include appropriate call out cover and ensure that good spares are available.

Fundamental to any maintenance regime is to ensure  the generator’s engine coolant heaters, or jacket heaters, are keeping the engine block warm and the mains trickle charger is charging the starter battery. The generator is started and stopped from a signal from the Automated Mains Failure (AMF) panel. This should also be checked in a maintenance regime to ensure it is working correctly. The generator on receipt of this signal will typically take 2-10 seconds to provide the power to supply the critical load. The UPS system should, using its batteries, support the load during this interim period.

The cooling system has active elements including a fan, water pump and thermostats as well as a radiator/heat exchanger, hoses and connections that should be checked for leaks. The fan drive pulley and belts should be checked for wear. The fuel system has fuel lines, connections and filters requiring checking, as well as the air and exhaust system components. The lubrication oil system, the starting system and the generator mechanics all have components needing checking for wear, and fluids that must be replenished or changed. Additionally, a load test, typically of two to four hours duration on full load, is recommended.

Onsite visits, though indispensible, cost time and money, so the maintenance plan should meet the clients needs without being excessive and more costly than necessary. During these visits, technicians can perform mechanical and electrical inspection and testing, replacing worn parts, replenishing and changing fluids as required. They can also spot critical component degradation and advise accordingly to arrange for a replacement or repair of the affected part. If required and permissible, the maintenance technicians can test the power protection system’s reaction to a simulated mains failure.

These scheduled maintenance activities are often combined in a maintenance contract with emergency call-out cover, where service levels and response times are set to match the client’s needs and the site’s criticality. Remote 24/7 generator monitoring and testing is another complementary and highly efficient maintenance plan component. Alarms, faults and valuable operational status information are relayed to the maintenance provider’s service centre. An appropriate response is then initiated, with improved ‘first-fix’ rates during site visits. This remote monitoring can have scheduled as well as emergency features. The generator can be automatically started at a pre-set time every week, and run off-load for 10 minutes while checking vital operating parameters including voltage, frequency, battery charge condition, oil pressure, water temperature, emergency stop button and fuel level.
With the UK power station population ageing, extended blackouts appear to be increasingly likely. A generator can effectively offer the required extra protection, above the UPS battery autonomy, ensuring increased power protection for your critical loads.

Our grumpy old man has been sampling the delicacies of duck feet, jellyfish and braised donkey on a Far Eastern sojourn, but his appetite for telling it how it is remains unabated

I have learned a lot in the past few weeks about the probable futility of our attempts to command the tides of global warming. Rather as King Cnut never actually tried to stop the incoming sea, but rather wanted to prove to his people that he couldn’t act as a god, the West’s environmental efforts may yet simply show we are powerless to achieve a clean Earth – at least in our lifetime.

I have just returned from China where I witnessed capitalism going mad. While still essentially a socialist state, with a reasonably strong Communist party, the country has embraced western consumerism in the most ostentatious ways. In Beijing, where traffic gridlocks lasting up to five hours are commonplace, new vehicles are coming onto the roads at a rate of 58,000 a month! Even in Cheng Du, a city of 10.5 million, making it medium sized by Chinese standards, there are 1000 new cars sold every single day.

Visit Shang Hai for the World Expo that’s taking place there and apart from seeing a bustling and vibrant state of the art city, you’ll also be blinded the glorious spectacle of a gazillion lights burning brightly through the night. And it’s all powered from coal. Shang Hai Electric Power Company (the largest of the city’s providers) posted profits in 2009 of RMB 382 million in spite of massive hikes in coal prices.

Against this backdrop, there remain huge tracts of land in the Far East that are still to be properly electrified. This is coupled with a crumbling infrastructure that, outside of the major cities, is unlikely to bear the increasing loads required. This means continuing investment in equipment, but it also means much more generating capacity is needed. Capacity that will almost certainly principally come from coal fired generation.

Paradoxically, China appears, at least superficially, to be very environmentally conscious. The plentiful waste bins deposited around the cities have recycling repositories. In some cities, only electrically powered scooters and mopeds are permitted. Many cities ban heavy goods vehicles from their centres. In Cheng Du, the city will shortly open not one, but seven underground electric rail networks – all at the same time!

China also, of course, retains its strictly governed one child per family policy, so it cannot be blamed for allowing uncontrolled population growth. No, its biggest environmental problem now comes from the expansion of consumerism that we have propounded for so long in the West.

I wonder how much China’s efforts, much like our own, will stem expanding greenhouse gas emissions.

I am a sceptic not a cynic, but one has to retain some objectivity to put into perspective the rhetoric of our politicians and green campaigners. I do believe in conservation. I do believe in reducing all forms of pollution. I do believe we face impending energy crises. But, I do not for one second believe our environmental salvation can come from current green energy technology and reducing consumption. Especially while demand from the world at large continues to grow exponetially.

What I am optimistic about is, with the right emphasis, resources and impetus, humans have the capacity to solve their problems technologically. After all, in homo sapiens’s short history on the planet, we may have screwed some things up, but we’ve solved an awful lot of others. In that, perhaps China’s emerging industrialisation may yet hold a key.

Secure power specialist Dale Power Solutions has begun its 75th anniversary year with 75% order intake growth in the first six months of 2010.

As it looks back on a history which has taken it from humble beginnings to a global brand, renowned for its technical expertise and engineering excellence, Dale's range of new and existing products is seizing a bigger share of the market.

In all sectors - generator sets, uninterruptible power supply [UPS] battery products under the Erskine brand and in service and maintenance - Dale is enjoying international success. As part of the secure power division of TT electronics, it now employs 600 people worldwide with circa $120 million per annum.  

Each year Dale supplies more than 3,000 generator and battery-backed UPS worldwide and services more than 4,000 generator sets and UPS systems. Key customers are in sectors as diverse as oil and gas, industry, telecoms, hospitals, finance, tourism, leisure, and many more.

Against a backdrop of global recession, Dale is currently recruiting new apprentices, graduates and experienced staff to further strengthen its operation as it looks to meet future demand.

A new containerised generator set, the Dale Secure Power Series, is already selling well, just months since its introduction. Aimed primarily at the hire market, the range includes the Secure 1600 which sets new parameters for off-the-shelf containerised generating sets, packing step loads of up to 800kW into a 20ft container.

Dale is continuously seeking new markets across the world and expects continuing strong demand to come from the petrochemical industry, already a key sector for UPS and DC products. Dale has developed a new range of standard UPS systems alongside its Erskine branded industrial UPS products, designed specifically to work with its range of generator sets to provide an integrated solution and guarantee continuous power to its customers.
A new range of service products is also in the pipeline, an area of the marketplace where Dale's vast technical background and expertise - going back 75 years - has already made it a global name. Comprehensive service and maintenance, drawing on a team of more than 80 service personnel, helps key clients worldwide protect and prolong the life of their products.
 

The excellent start to 2010 has delighted managing director Tim Wilkins. He puts it down to a positive proactive workforce working very hard to meet customers' demands together with a strong product line-up and the development of new sales and service outlets, most recently in Swindon, Aberdeen and Sharjah.

"We have seen a very strong order intake for the first six months of 2010 and are pleased with the success of new and existing products," he said.

"We have strengthened our sales department and thanks to our new range of products and the strength of our existing generator, UPS and sales and maintenance products, we have captured a greater share of the market, both in the UK and export."

He puts the longevity and success of the brand down to excellent technical expertise, design capability, project management, installation and ongoing servicing.

"It continues to be our ability to discuss a customer's requirements with them and supply a tailored power solution that meets their needs exactly," he said.

"We operate lean enterprise 6 Sigma working practices and the Dale brand has become synonymous in the power industry with providing customers with an immediate, pro-active response and a perfect technical solution to their requirements."

"Whether it is off-shore oil and gas platforms, the stock exchange or a hospital operating theatre, our products and expertise are now an integral part of many large, blue-chip companies' risk and disaster recovery management plans."

Looking ahead, the company's business plan is to achieve continued growth, driven through increasing sales in existing and new markets, on a world-wide basis. It is also keeping an eye on the future and where the next generation of "green" products will emerge from.

"We are constantly looking for opportunities to develop new products, to increase our offering to our customer base and develop new markets," Mr Wilkins added.



Background

The Dale Electric Group of Companies began in 1935, starting out as one man operating from his garden shed. In 1938 Erskine was founded and 30 years later was acquired by Dale Electric. In 1980 Dale opened the Dale Ottomotores generator manufacturing plant in Mexico.

Dale was acquired by TT electronics plc in 1994 and a year later the group also acquired Munradtech, Dawson Keith and Scorpio, five years later merging the brands. In 2009 offices were opened in Swindon, Aberdeen and the Middle East.

Its main UK office is now on the Eastfield Industrial Estate in Scarborough with its European Development and Test Centre at nearby Filey.

It has sales and service offices in Aberdeen, London and Swindon and in Brazil, Mexico and the United Arab Emirates.

Dale Power Solutions plc

Phone: +44 (0)1723 583511     

www.dalepowersolutions.com 

The ever-increasing political pressures on the global power generation industry to meet demanding climate and energy targets is driving the increased use of renewable energy sources such as wind and solar power. As a result, electricity generation is becoming more decentralised and more intermittent. This calls for new types of power grids with both the flexibility and intelligence to receive generation of all qualities and quantities from diverse sources, and the capability of managing them to deliver reliable consumer supplies, explains Michael Lippert, Saft ESS (Energy Storage Systems) Division

Much of the debate on the nature of these new smarter grids has been focused on issues such as clean power generation, smart metering and information. Now though, there is a growing appreciation that smarter grids will almost inevitably feature some form of energy storage to provide the vital continuity and quality of supply needed to ensure electricity is available wherever and whenever demand - rather than supply - dictates.

A specific area where energy storage is set to make an early impact on smarter grids is in helping to boost self-consumption in grid-connected solar PV (photovoltaic) installations.

Boosting self-consumption for on-grid PV installations
By 2020, PV is expected to account for up to 12% of all generation in Europe, with a total installed capacity of some 390GW, with two-thirds of this being decentralised (source EPIA: ‘paradigm shift scenario'). PV installations with a permanent connection to the electricity grid are categorised as ‘on-grid' applications. This is currently the most popular type of PV system for homes and businesses in the developed world, comprising more than 90% of all PV installations.

A typical domestic PV installation in Europe, such as those now especially popular in Germany and Spain, is sized to deliver around 3,000kWh/year. With the average yearly energy consumption in those two countries running at 3,500kWh it is clear an energy conscious household with an efficient PV system could be capable of meeting all its energy needs itself. However, the current practice is to inject all of the PV energy produced by domestic schemes into the local electricity network, to be sold to the local utility. The household still imports all the electricity it needs from the network.

In the near future, it is expected we will see a significant change in this operating model as households aim to become energy autonomous. This means they will both produce and consume their own electricity, using a local energy storage system to store any excess PV energy until it is needed. In essence, the PV energy produced will need to be ‘time-shifted' from the day-time, peaking at noon, to make it available on demand in the evening.

The introduction of energy storage will both maximise local consumption and enhance the efficiency of the PV system. Only surplus energy would be fed back into the grid, and it is even possible the owner of the PV system might be remunerated at a higher tariff during peak demand periods. The indications are future legislation in Europe will favour this type of ‘self-consumption', especially as the clear indication of the change in energy value and availability throughout the day will encourage households to adopt a much more energy conscious attitude.

Security of supply and deferment of grid upgrades
In addition to helping the shift towards self-consumption, energy storage can also increase security of supply while making individual consumers less dependent on the grid. This will help to stimulate the development of energy self-sufficient houses and buildings and contribute to the continuous growth of PV as part of the global energy mix.

For utilities, the main benefit of on-grid energy storage is it will reduce the peak load on their grid while at the same time making PV a source of predictable, dispatchable power they can call on when needed. There is also the potential to defer costly grid upgrades needed to meet increasing demands for power.

The anticipated implementation of smart metering and real time pricing will enhance the use of demand side management techniques and serve as a major tool to help balance load versus demand in future distribution networks. With such market mechanisms in place, end users can play an active role in optimising energy consumption whilst maximizing the ROI (return on investment) of their PV system. Energy storage enables them to do this without any reduction in their home comforts.

On-grid energy storage - the operational model
A typical residential PV system with a panel size of 3kW produces a daily average of 8.5kWh throughout the year in Northern Europe, ranging from 3kWh in winter to a peak of 12kWh in summer. About 4.5kWh of the PV energy will be used directly (self-consumed), as soon as it is produced. There is therefore an average excess of 4kWh - with a seasonal range of 1kWh to 6kWh - that can then be stored until needed. So an energy storage system will need to ‘time-shift' between 1 and 6kWh per day - averaging 4kWh.

Li-ion battery technology
In grid-connected energy storage applications, the newest practical battery technology, lithium-ion (Li-ion), offers the potential for significant improvements in terms of performance and service life over conventional storage batteries, and it is also zero-maintenance. However, although Li-ion batteries are very well established in consumer applications, the more rigorous demands of PV applications means ordinary consumer cells are not suitable. Instead, a new generation of Li-ion battery systems designed specifically for industrial applications is under development, with the first systems already on field test.

The initial indications are Li-ion technology will offer both very high efficiency, of around 95%, combined with a long calendar and cycle life - 20 years at 60 percent DOD (depth of discharge)/day.

The compact, sealed for life design of Li-ion batteries also offers considerable advantages. Considering a minimum capacity of 5kWh, then using Li-ion batteries it would be possible for a compact domestic battery to only take up 50 litres or so of space - similar to the footprint of a fridge-freezer.

Guadeloupe grid-connected energy storage project
A current project on the Caribbean island of Guadeloupe is testing the viability of using Li-ion batteries in conjunction with PV systems. 15 PV systems have been deployed over 10 sites, each consisting of an array of 2kW PV panels and a 210/280 V, 10kWh Saft Li-ion battery system that provides buffer storage for the grid-connected PV units.

During peak periods, the PV systems provide a controlled injection of 4kWh daily to the grid, upon utility demand - one hour in the morning and three hours in the afternoon, simulating the substitution of fuel powered generators.

Results from the two-year test period have shown the average daily cycle for the batteries is 45% DOD. This corresponds to about 50% of the generated PV energy stored at a battery efficiency of 97%. The expected payback time on the investment is between six to 10 years, depending on the prevailing cost of peak power.

US DOE SEGIS and SMUD projects
A Saft Li-ion battery system, sized at around 10kWh, will provide energy storage for one of the ‘Solar Energy Grid Integration Systems' (SEGIS) projects funded by the US Department of Energy (DOE). The objective of the SEGIS program is to develop high performance products that will allow PV to become a more integral part of household and commercial smart energy systems.

Similarly, a Saft Li-ion battery will supply renewable energy storage for the Sacramento Municipal Utility District's (SMUD) PV storage pilot programme at Anatolia, Ill, a high penetration PV community within SMUD's service territory. The two-year pilot project is being funded by the DOE to examine the value of distributed PV coupled with energy storage in 15 homes and three sites on SMUD's distribution system within the community.

Efficient energy storage will enable solar power to be time-shifted to support SMUD's ‘super-peak' from 4pm to 7pm, particularly when PV output drops off after 5pm

Sol-ion, Europe's largest PV energy storage development project.
In the EU-backed Sol-ion project, Saft has joined forces with industrial partners Voltwerk and Tenesol, as well as with French and German research institutions. The aim is to create an integrated energy conversion and storage kit, capable of production on an industrial scale, for decentralised on-grid, residential PV systems.

The development phase of the project, which commenced in August 2008, has been completed recently, and it is now moving into its test and evaluation phase. This involves the deployment of 75 Sol-ion energy kits for field trials across France and Germany.

The Sol-ion trials will see Li-ion (lithium-ion) batteries used in PV systems on the largest scale ever tested in Europe. The trials will be used to assess the performance of the technology, its economic viability, the added value of energy storage in an on-grid system and the benefits to stakeholders. The project will also investigate the impact of energy storage on demand side management issues such as peak shaving effects and the potential for integration within future smart grid concepts.

The Sol-ion kit has been developed to accommodate PV energy production of 5kWp (peak) with a battery rated from 5 to 15kWh and a nominal voltage of 170V to 350V. Li-ion is the only technology that meets the project's need for 20-year battery life in demanding environmental conditions.

The energy conversion and system management systems are designed to handle four system functions: multidirectional energy flows; self-consumption; grid support; back-up. They are also intended to handle requirements for demand side management such as control over storage and loads using smart metering, and integration within future smart grids that will need to handle demand response and dynamic pricing.

The Sol-ion battery is based on Saft's high energy Li-ion modules, with a nominal voltage of 48V and 2.2kWh capacity. These compact, maintenance-free modules feature an advanced and robust industrial design, and they can easily be connected in series or parallel to create the desired voltage and capacity for each installation.


Conclusions
- Energy storage is a vital element in smarter grids
- Distributed on-grid PV systems with battery energy storage can effectively ‘time-shift' production, making electrical power available when it is needed.
- Decentralized storage provides value to all stakeholders
- Li-ion is a promising energy storage technology and industrialized systems are being developed and trialled

There is a lot of debate about the use of biofuels in the press.  David Hatherill, engineering manager for Finning Power Systems, takes a closer look at what needs to be considered for its use in generator sets

In recent years there has been an increasing interest in the use of liquid biofuels for fuelling compression ignition engines. With world production of biofuels, such as biodiesel, increasing at an average annual growth rate of 40%, there can be little doubt this interest is set to continue.

It is necessary, therefore, to understand the different aspects that affect which fuels are viable and which are not, taking into account the factors that are important to the engine in a generator set.

Biofuels
When used in its broadest sense, the term biofuels can be confusing, After all, wood is a biofuel, so some form of classification is clearly needed.

Liquid biofuels include not only oils that are liquid at room temperature, but also materials that are solid in their normal state but, when heated, form a liquid containing combustible energy. They are largely derived from vegetable oils, such as rapeseed oil, palm oil and soyabean oil, or animal fats, such as tallow and chicken fat.

In addition to vegetable oils and animal fats, the use of waste materials, such as sewage, to grow algae may play a big role in the future development of biofuels. It is predicted fuel derived from the growth of algae has the potential to produce 30 times more energy per acre than land crops, such as soyabeans.

Some of these sources are available domestically and can play a part in reducing our dependence on imported oil.

Biodiesel
Biodiesel is a subset of liquid biofuels and is specifically a non-petroleum based diesel fuel. The production of biodiesel involves reacting vegetable oils or animal fats catalytically with a short-chain aliphatic alcohol, typically methanol or ethanol. This reaction, known as transesterfication, produces an alcohol ester that possesses physical properties very similar to petrochemical based diesel fuel. 

This fuel can be used in most standard diesel engines as the primary fuel source. To fuel an engine, biodiesel can either be used alone, as 100% biodiesel, or can be blended with conventional petroleum diesel. A 100% blend of biodiesel is known as B100. If biodiesel is blended with conventional petroleum diesel, this figure reduces. For example, a blend of 20% biodiesel with 80% petroleum diesel would be referred to as B20.

The current European standard describing the minimum requirements for biodiesel is EN 14214. It is anticipated this standard will be revised in the foreseeable future, due to the fact EN14214 was originally an RME (Biodiesel made from rapeseed) standard and has some deficiencies when applied to biodiesel from a broader range of feedstocks.

In principle, biodiesels conforming to EN 14214 can be used at up to 100% in diesel engines. However, some third party fuel injection equipment (FIE) manufacturers have warned against using over 5% biodiesel blends, as their equipment was not designed to run on such fuels.
Some manufacturers do, however, provide biodiesel compatible components. Seeking expert advice from the manufacturer or dealer is therefore advised.

Fuel standards
Most engine manufacturers set their own standards for liquid fuels, and in general these are wider than the universal fuel standards within any given market: EN590, BS2869 etc.  Manufacturers will be able to advise on the relevance of such standards and also interpret which are relevant to a specific project.

Fuel quality impacts far beyond its combustibility so it is important to work closely with your service provider to develop a suitable maintenance regime.

Emissions
The major advantage of biodiesel fuel is that it can be produced from spent oils including by-products from other industries, such as used cooking oils, although careful control of feedstock is required to ensure consistent quality.  The emissions from biodiesel engines can be significantly less polluting than standard diesel fuel as they contain little to no sulphur, but adjustment of the engine is required to meet these levels. A non-adjusted engine will generally produce more nitrogen oxide than the same engine on mineral diesel.

Density and calorific value
Whilst the density of biodiesel is slightly higher than conventional petroleum-based diesel, the calorific value is slightly less. This means a greater volume of biodiesel must be injected to achieve the same power output as petroleum diesel.

If a particular unit is only going to be run on biodiesel, it may be acceptable to adjust the injection system to cater for any loss of power. However, if a unit is to be run on either fuel, such adjustments in the injection system may cause the engine to over fuel when run on petroleum diesel.

Cold weather performance
The properties of biodiesel are such that its waxing and cold filter plugging point (CFPP) occurs at much higher temperatures than petroleum diesel. The application and location in which the biodiesel is to be used must therefore be taken into consideration. It may be necessary to use a fuel additive to prevent filter plugging, but these can be expensive.

Lubricating oil degradation
The use of biodiesel and raw vegetable oils has been linked to problems regarding the degradation of engine lubricating oils, with early oil changes often being required. As a result, most engine manufacturers recommend regular Scheduled Oil Sampling (SOS) until this factor is better understood and biofuel tolerant lubricating oils are available. Current lubricating oil blends are designed for mineral fuelled engines. As more biodiesel applications are installed it is anticipated the oil industry will begin to provide specialist oils.

Storage
Since biodiesel is an effective solvent, there are a number of potential issues associated with its storage. Existing tanks should be thoroughly cleaned before storing biodiesel, as any existing sludge is likely to be dissolved, which may lead to blocked fuel filters.

Biodiesel is known to dissolve some of the paints used to coat the inside of fuel storage tanks. It is also known to react with copper, bronze, brass, lead, tin and zinc. Stainless steels and aluminium are unaffected. Fuel supply and storage systems should be built with this in mind.

Plastic tanks should be avoided, unless known to be compatible. Some nitrile and natural rubbers are also known to be affected by the use of biodiesel.

Further to this, it should be noted biodiesel has a limited storage life. It is recommended biodiesel is used within six months. After that period, the fuel should be reanalysed to ensure it still meets EN 14214 specifications. Additives are available to extend the storage life of biodiesel.

Other vegetable oils
It is advisable to check with the engine manufacturer before considering other vegetable oils as potential fuel sources. 

They are rarely recommended and on balance do not work in the long term unless additional fuel conditioning infrastructure is installed. If this is not used, engine performance and emissions will rapidly deteriorate. This is due to incomplete combustion and the build up of large amounts of soot in the combustion chamber.

A quick search of the internet will produce a plethora of reports charting the demise of various test engines that have used a variety of crude vegetable oil fuels without fuel conditioning. It is possible to fuel larger, heavy fuel engines with untreated vegetable oils after some on site pre-treatment, but such systems are only economic from about 2-3 MWe upwards. In short you should always consult the manufacturer or dealer.

Warranty
Finally, one of the most frequently asked questions by an end user is how the use of biofuels affects their warranty.

This is a question that needs to be answered by each individual manufacturer, but for illustration I can outline Caterpillar's stance.

Caterpillar warrants the engine against defects in material and manufacture and will do so on any engine using biofuel.  It follows, however, any damage caused as a direct result of using biofuel could not have been caused by a defect in material. To this end it is advisable the fuel specification should be agreed in advance with the manufacturer.

The debate about using Biofuels will continue to rage.  You should seek professional advice if you are considering such an option; after all generator sets for standby power or as a prime mover are a big investment.

For years the UK has been slow in realising the potential of solar photovoltaic (PV) cells as an electricity source, relying on the more conventional energy sources we are all used to, such as oil and coal. However, it's hard to turn on the television these days without hearing about how to save electricity or cut down our carbon footprint. As an electrical contractor, it doesn't matter if you're worried about your carbon footprint or not, the potential to earn money out of this green frenzy is energising enough says Emma Hughes, Solar Power Portal UK

Back on 1 April, the UK government's Department of Energy and Climate Change (DECC) introduced the feed-in tariff (FiT). This government-backed support measure is designed to increase the uptake of microgeneration and help deliver the UK's 2020 renewable energy targets. It does this by providing those generating renewable energy with a 25-year guaranteed per unit support payments (p/kWh) for electricity generation. These payments, which are currently set at 41.3p/kWh, are paid by the energy supplier. This reward means by installing a solar system of just 2.5kW you could cut up to £9,000 off your electricity bills and earn up to £40,000 over the 25 years the FiT is paid for.

The incentive to install solar PV is clearly there; you could earn a significant profit over the time period the FiT is paid for. Furthermore you can save money on your electricity bill and look after the environment at the same time. However, you have to be properly certified to install a system on your house, and this is where the government comes into play again.

The Microgeneration Certification Scheme
Solar PV forms a key technology set within the Microgeneration Certification Scheme (MCS), which offers government (DECC) grants for the installation of microgeneration based products and systems. To benefit from the UK's feed-in tariff, every installer of solar PV in the UK must, by law, have MCS accreditation.

The MCS is an internationally recognised quality assurance scheme and mark for LZCT installers as well as products, which was designed with input from installer and product representatives. Similar to the Gas Safe Register, the MCS gives the installer a mark of competency and demonstrates to customers the installer is able to perform to the highest quality every time.

Since the solar industry is set for quite rapid growth, installers should aim to become certified as soon as possible, since they will be the preferred option in order to earn the FiT. The DECC links MCS to many of the key factors driving demand, such as:
- FiTs, which will provide guaranteed payments to individuals, business and communities for small-scale electricity generation. For technologies where there is an MCS standard, both the technology and the installer must be MCS certificated to be eligible;
- The Renewable Heat Incentive is planned for 2011 and will provide cash-back to individuals, business and communities for renewable heat generation. The government has indicated that the Renewable Heat Incentive is being linked to MCS products and installers;
- The Low Carbon Buildings Programme and Energy Saving Scotland home renewables grant schemes (heat technologies only) require MCS certificated products and installers to be used;
- The Code for Sustainable Homes, which is a mandatory requirement for all newly built homes to meet sustainability ratings, including ratings for energy and CO2 emissions. MCS certificated technologies can be used to meet the requirements of this Code;
- Planning permission for consumers for certain renewable energy technologies has now been made a lot simpler thanks to permitted development rights introduced in England and Scotland; and
- The Standard Assessment Procedure (SAP) for Energy Rating of Dwellings recognises MCS certificated products when determining whether products are eligible for inclusion in SAP assessments.

To take advantage of this growing demand installers should be considering the certification process and how they can get involved now.

How can you get involved?
- Become a fully certificated MCS installer company - gain your own certificate;
- Work full time for a certificated MCS installer company - MCS certification is for the company. There are plenty of existing MCS companies looking for skilled staff; or
- Become a sub-contractor to a certificated MCS installer company - if you want to remain independent but feel you would like to work in this field, you could be a sub-contractor to an MCS certificated company. See rules for subcontracting within the installer standard.

Training and courses
Alongside MCS certification, it is also important to learn how to work with this up-and-coming technology. The installation process is not difficult for a fully-qualified electrician to grasp, yet it is slightly different from the technology worked with on a day-to-day basis.

Since the introduction of the feed-in tariff, more and more courses have appeared for installing solar photovoltaic systems. Some of the courses are offered by MCS certified companies, giving electrical contractors the opportunity to learn about the systems they will use for free. Some will be trained on the job, adding a practical element to their course. It is important the course details are fully researched before paying out any money, as an illegitimate course is as good as not taking a course at all.

The NICEIC has announced details of a new solar photovoltaic course it has developed to support its MCS for installers. The course provides electrical contractors with knowledge and skills about this energy generating technology. The new course covers the majority of small-scale systems currently being installed in the UK and provides an overview of the design, installation, commission and service of solar PV systems.

"NICEIC is at the forefront in promoting microgeneration and we encourage all electrical contractors to get involved with this growing sector," said Wayne Terry, NICEIC's head of energy and environment. "NICEIC's new Solar PV course provides an excellent way to acquire the necessary skills and knowledge to maximize the revenue generating opportunities microgeneration offers."

Is the future really bright?
Following the right path to becoming a certified electrical installer is all well and good, but if the market doesn't accelerate, there will be too many installers and not enough jobs. Luckily, since the introduction of the FiTs, this problem has faded like a battery-powered lamp.

The uptake of solar in the UK has increased dramatically in the past four months, reaching a total of over 11 megawatts according to energy regular Ofgem. This figure is expected to climb yet more over the next 12 months, as more and more free solar installation offers appear. Several companies are now appearing on the market, offering to ‘rent' rooftops for the installation of solar PV. These companies then benefit from the FiTs, while the homeowner gets to shave pounds off their electricity bill and make use of renewable energy.

This is a win-win situation for all, especially qualified electrical contractors. With these companies experiencing momentous interest in their offer (one company receiving five calls per second), the outcry for installers is hard to ignore. Offers such as these, which will spur the growth of the industry, as well as making others aware of the profit potential available, will increase the amount of jobs obtainable on the market for electrical contractors.  

Light at the end of the tunnel
While the potential for the UK solar market has been planted, the seed cannot grow effectively without the nurture of education. The information outlined within this article is readily available, should you know where to look for it. However, someone needs to turn that light bulb on for many. One such helpful resource in this fledgling industry is the Solar Power UK 2010 Conference, the first official event of the Solar Power Group, a division of the REA and the voice of the solar power industry in the UK. This two-day conference and exhibition will offer insights from top experts in the field, to all the different issues facing this up-and-coming market. It will be the first step in uniting all the major players in the UK solar industry to enable the UK solar market for 2011.

An exclusive gala networking dinner will be held as an accompanying event to the conference, thus opening the opportunity for further networking and business development in an elite environment. Electrical contractors will have the opportunity to meet and talk with qualified installers, to learn through industry experience how the PV industry really works, and to hear what it is like to be part of it. For more information and to register for the conference, please visit http://www.solarpowerportal.co.uk/spuk10 and enter the following code: "RESONATE483"

As UK power grid conditions give rise to extended power outages, long term generator autonomy is becoming an essential complement to the UPS's ‘no break' power protection capability. Uninterruptible Power Supplies generator manager, Kevin Ashton, considers how to match a generator to the onsite UPS, critical load and environmental conditions (PART 1 OF 2)

Uninterruptible Power Supplies (UPSs) perform an essential role in protecting organisations that cannot tolerate any electrical power interruption. If the mains fails, the UPS's battery seamlessly takes over until power is restored. However, UK electricity grid problems are increasing the likelihood of extended failures that could exceed the UPS battery's available autonomy. A standby generator and fuel supply can solve this, but unlike a UPS, a generator cannot come online seamlessly when the power fails. Therefore a matched generator - UPS pair is essential for truly uninterrupted, ongoing power protection.

To successfully install a generator, it must be matched to the UPS, sized correctly for the onsite load, and installed into an environment that is designed to accommodate it.

Generator-UPS matching is important as otherwise each can cause problems for the other. Generator output voltage is usually acceptable to the UPS, but its output frequency range, under fluctuating loads, may be too wide for the UPS to accept. The generator frequency rate of change, or slew rate, may also be too fast for the UPS to follow safely. Such problems can be prevented by ensuring the generator is fitted with an electronic governor maintaining its output within tight frequency limits.

Meanwhile, UPSs typically have a rectifier charger control circuit which imposes notches on the power feed, interfering severely with some types of generator control. Additionally, some charger circuits draw non sinusoidal input current, creating harmonics, measured as total harmonic distortion (THDi). These can cause de-rating of the generators output, especially as some UPSs generate up to 30% THDi. Also, generators cannot usually tolerate 100% of their rated load being applied in a single step.

However, careful choice of UPS topology can pre-empt such problems. Transformerless technology can achieve a THDi of below 3% at full load, while a separate battery charger circuit, together with a Generator 'On' signal between UPS and generator reduces the UPS battery charging current, in turn reducing load, notching and heating effects on the generator. Step loading on the generator is controlled primarily by soft start of the rectifier current, eliminating high current peaks during mains recovery. Sequential switch-on of UPS rectifiers as a parallel array within the UPS is another possible way of reducing UPS step loading on the generator.

The generator must be sized for its critical load as well as matched to the UPS. This may comprise emergency lighting, air conditioning, building alarm systems and other services as well as the UPS load. For example, there is no point in maintaining power to ICT equipment without also supporting the air conditioning essential to maintaining equipment-acceptable ambient temperature. It is also good practice to work to the generator's continuous rating rather than its higher standby rating, as it can be called upon at any time to work for any duration.

Planning the chosen generator's installation is subject to several environmental and physical considerations. Once the autonomy has been established, the amount of fuel required and means of storage can be established. Bunding is essential to ensure fuel oil cannot leak into the water supply. Positioning of the generator is influenced by further factors that must all be allowed for. For example generator start-up and running noise may be acceptable in a given location during the day, but intolerable at night. As the mains can fail at any time, either a different location must be chosen or a ‘bespoke' acoustic housing used. The cost of this increases with its attenuation rating.

All generators produce heat as well as power, which is mostly removed by air cooling. Therefore, generators are typically located outside, in weatherproof and acoustic enclosures, where a plentiful supply of cooling air is assured. An outside location also allows easier exhaust fume venting, obviating problems associated with installing exhaust pipes within buildings. For internal installations within buildings ventilation and noise requirements can be given using specialist acoustic equipment such as attenuators and exhaust silencers. These are often manufactured specifically for the application and the complete system assembled on-site by specialist installation engineers. 

Other physical considerations are also important. Even a small 100 kVA standby generator weighs several tonnes, weight which must be allowed for when planning its delivery and positioning. Special delivery vehicles and lifting equipment may be needed. The generator should also be as close as possible to the main electrical installation to minimize runs of expensive power cable, as well as volt drop losses.

Adding a generator calls for legislative compliance as well as satisfying the site's environmental considerations. Local authority planning requirements vary with area, so it is essential to check these before installing a standby generator. If large quantities of fuel are to be stored on site then compliance with the Environment Agencies PPG02 regulation is required.

All of these factors are important to the success of adding generator capability. However, with planning none are particularly onerous, and the benefits of generator protection can far outweigh any inconvenience or cost.