Circuit training
Alistair Welch reports on how established fuse developer and
manufacturer Cooper Bussmann is targeting the renewables market
Fuses might not be glamorous, but when it comes to protecting electrical equipment glamour is not really a top priority. This is as true in the renewables sector as in any other area of electrical engineering. Cooper Bussmann, a division of US giant Cooper Industries, has been manufacturing fuses for over 80 years and its UK arm, based in Leicestershire, employs around 200 staff. According to Simon Pinkney, the company’s Marketing and New Product Development Director, the renewables market, primarily wind, electrical vehicles and photovoltaic applications, currently accounts for 15 percent of business. The company’s aim is, in Pinkney’s words, to “very quickly be the number one fuse manufacturer and provider for the renewable energy sector”.
Principally a manufacturer of fuses, the company’s products typically protect the power conversion stage of a technology - in photovoltaic applications, for example, converting the current from DC to AC before transmission to the grid. The advantage of a fuse over a circuit breaker is that in the event of a fault a fuse will stop the current much sooner than a circuit breaker typically would, minimising the possibility of damage to equipment.
The company’s business in the solar sector grew by some 300 percent in 2010 and similar growth in the wind sector is being targeted keenly over the coming years - especially as the offshore wind market continues to mature.
Pinkney explains that an important differentiating factor of Cooper Bussmann is its staff’s ability to speak to clients on an engineer-to-engineer level: “We would not employ a salesman who does not have the necessary product expertise. I want to have a peer-to-peer conversation with a client; we want to show you what we are developing.”
“It’s about understanding the customer’s application need and where our product fits in. We have experienced a number of situations where a company looks to us for advice with its application,” adds Product Manager Ben Rooke.
Thanks to the expertise of the personnel employed at Cooper Bussmann UK, the company is able to discuss a client’s particular requirement and move towards a bespoke solution. The fact that the company recently hired an engineer with a PhD in solar converters demonstrates that it is taking provision for the renewable energy market extremely seriously. According to company legend, in the early days of the 20th century, to work for the company even as a salesman you needed to have an honours degree in electrical engineering. This commitment to high intellectual standards within the organisation, it appears, is still present today.
Whilst admitting that the group is essentially in the business of manufacturing a volume product, Pinkney explains that, especially in an expanding sector like renewables, there is still room for innovation: “The market is not mature yet; take solar panels, for example: installation codes are not yet fully developed for this market. Whilst there might be a predetermined footprint that a product needs to sit in and there are predetermined dimensions for certain products, internal specifications tend to be bespoke for each application. We need the intellectual horsepower in our organisation to develop new products as the industry moves forward.”
Furthermore, as wind turbines in both onshore and offshore contexts continue to increase in capacity, further pressure will be placed on efficient energy conversion. Designing bigger fuses to safely handle more current for such applications is where Cooper Bussmann hopes its expertise will come in to play.
“The voltage will eventually increase to 1500 to 2000 Volts DC,” predicts Project Engineer Nigel Nurse. “We are already having conversations about both standard and bespoke technology to handle this.”
“We want to be seen as an innovator and a technical differentiator, that’s at our core,” adds Pinkney.
In addition to investing in people, Cooper Bussmann UK is also investing in its facilities. A substantial refurbishment of its Leicestershire headquarters is nearing completion, including space for a lecture theatre, a technical library and a number of seminar rooms. Following the redevelopment, the idea is to instigate an education programme to ensure that all of the company’s employees have a working knowledge of fuses and their applications.
According to Pinkney, courses will be offered at three different levels: “Fuse School”, “Fuse College”, and “Fuse University”. Fuse School will be the entry level course designed for all employees, from shop floor to office with no previous experience or knowledge in the sector. On completion of the first stage students can then graduate to Fuse College, whilst Fuse University will allow the company’s top engineers, many of whom have years of experience in the industry, to continue their professional education.
“We are hiring smart people,” says Pinkney, “And we have also made a significant investment in our technology centre - we don’t only want to develop products, we want to discuss, inform, educate and share ideas.”
His words are testament to the fact that Cooper Bussmann is determined to be at the forefront of current protection for renewable energy projects. The company is committed to developing its technologies to best suit the needs of the sector.
Fuse development
Ben Rooke, Product Manager at Cooper Bussmann, discusses the significance of fuse development in the solar sector
As with many developing energy industries, the photovoltaic (PV) electricity market faces a number of challenges. There is the political wrangling over Feed-in Tariffs and, of course, considerations concerning cost and performance. There is already pressure on the manufacturing costs of PV cells, with many arguing for the development of large robotic assembly plants to drive down initial cost and deal with increased demand in the future.
There will inevitably be moves to extract greater efficiencies and power from PV installations, which, by extension, will require improved system overcurrent protection. Already the global trend is for the use of higher voltages of up to 1,000V DC and beyond. This has put pressure on PV system OEMs to source and install protection solutions that are not only capable of meeting the protection requirements, but are also easily packaged.
It is worth reminding ourselves that in faulted circuits PV modules may be damaged by reverse overcurrents. Typically, the effects of fault currents may range from permanent damage to PV modules and reduced efficiency to broken conductors resulting in electric arcs and fire. Dangerous fault currents can originate from external sources, from modules that are connected in parallel to the faulty string, from storage batteries in the system or from backfeeding through grid-interactive inverters. However, correctly rated fuse links are able to protect PV modules or strings and internal wiring against these dangerous reverse overcurrents.
As a manufacturer of fuse links Cooper Bussmann is constantly receiving approaches from PV power system manufacturer for solutions that meet these challenges. Typically they are looking for certainty and assurances in terms of proven performance and capability. Unlike typical grid connected AC systems, the available short circuit current on the DC side of a typical PV system is limited and the overcurrent protective device needs to operate effectively on low levels of fault current. To this end we have conducted extensive research and developed devices that are specifically designed and tested to safely protect PV systems with high DC voltages and low fault currents.
The result is a range of fuse links that meet all the specific requirements demanded by PV system manufacturers - most notably protection up to 1,000Vdc. The Solar PV range offers class-leading performance and is suitable for industry standard dimensioned 4,5 and 6 in solar cell based panels. In addition they have been tested to withstand the typical cycling conditions specific to solar panel operation and the environment stresses associated with system location. In effect this means that the fuse link will perform to its optimum level throughout the lifetime of the system.
Packaging is also a key criterion for system OEMs. With space limited in combiner boxes because of the desire to minimise the footprint and to improve the overall aesthetic, the preferred dimension for the fuse link is 10x38mm. This globally accepted package size is further enhanced by a choice of mounting options with standard ferrule, bolt and versatile PCB mounts on offer. The low power dissipation of the fuse link also improves efficiency and reduces heat generation within the combiner box.
What is certain is that, as PV systems evolve with new equipments, new wiring procedures and methods of installation, the development of the PV fuse link will continue in tandem. As the asset value of PV energy systems increases, in terms of the revenue that can be generated, it would be wholly inappropriate and commercially suicidal not to protect that asset with a product that meets the necessary performance requirements and standards.
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