Insight > Technology investment and is going to be used for some of the development process we’re doing for other parts.” Part of that focus on quality can be explained by mistakes that surfaced with Areva’s previous model at the Alpha Ventus wind farm. A problem with the gearbox, which first arose in 2010, led to serious overheating on the machines. The mistake was corrected quickly and transparently, but it taught the company some important lessons about supply chain monitoring.
speed. Our broader experience with the turbine has been extremely positive, however. It’s functioned very well since we made the original repairs.”
New challenges of transport and installation Other important issues around transport and installation also need consideration. Moving to a bigger machine like the M5000 creates a series of headaches around design. The turbine needs to be
We want to spot any mistake in the production when the machine is still onshore. That will help us save a lot of time when we go offshore. “It’s worth remembering that the company is still very new,” Huby says. “It was part-purchased by Areva back in 2007, but full integration of the group was only finalised in 2010. With Alpha Ventus it became clear that all the processes required were not yet up to
as light as possible to make loading and transport simple. Erecting the blades is also difficult, particularly with high wind speeds and hubs that are hard to turn. “We’ve developed an innovative installation solution,” Huby says. “Instead of putting the three blades
on the hub onshore, we go offshore without actually assembling the blades. That saves a lot of space on the deck and ship. When you do go offshore, you can stick the blades on the hub and position it properly. We are not competing with people who sell installation equipment, but we are partnering with them. “The offshore industry is still very young. If you look at the purpose of governments and companies, there are thousands of megawatts due for installation over the coming decade. Future success depends upon working as a team, with investors, suppliers, installation and cable companies, and with other competitors across the board.” Having made the choice of offshore wind at an early stage, Huby hopes Areva will become a leader in the European market in the years to come. As the sector looks to attract long-term investment, the company will need all the political and technological help it can get can get to achieve that goal.
HARTING Hall effect current sensors People | Power | Partnership
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Completely embedded electronics
With optional signal cable
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Various installation possibilities
Precision and Resilience
www.HARTING.com
Modern power electronics needs precise and secure current measurement, especially at high currents beyond 200 Ampere: HARTING Hall effect current sensors are designed for currents between 200 A and 2000 A and for use in harsh conditions. Precise, robust, for applications such as rail technology and renewal energy. In addition, easy to integrate by using a standard footprint. HARTING: Pushing Performance to innovative solutions. Please contact: HARTING Electric GmbH & Co. KG Wilhelm-Harting-Straße 1 | D-32339 Espelkamp | Phone +49 577 247-97100 | Fax +49 577 247-495 | electric@HARTING.com
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Company insight > Technology
Current sensors for power electronics A swift and precise current measurement is needed for the exact regulation of power electronic systems such as frequency converters, switch-mode power supplies and UPS systems. Developed specifically for these systems, HARTING current sensors offer high levels of accuracy and interference resistance.
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Two alternative measurement principles
ower electronics is a key technology, not only in markets such as transportation, but in renewable energies as well, and is one of the most significant application fields for HARTING solutions. HARTING is the market leader in electromechanical components and systems for these applications. Now steadily expanding its product range, HARTING has added new sensor components and developed innovative solutions that meet the increasing requirements in such applications.
Information tip The current sensors from HARTING are designed for the field of large power electronics. Therefore, their contribution in the field of wind energy can be summarised as improving the safety and efficiency of modern wind turbines. The Hall Effect current sensors in HARTING’s product range are suitable for measuring AC or DC types of current and PWM signals. In addition, they meet the industry requirements for electronic equipment used in power installations, namely DIN EN 50 178. The current sensors from HARTING are characterised by high accuracy and interference resistance and, because of their standard mounting dimensions, it is easy to incorporate them into different applications. There are different types available, featuring rated currents from 200 to 2,000A, measurement ranges from 300 to 4,000A, as well as precision from 0.5 to 5%. The sensors operate in the temperature range from -40 to +85°C.
With open-loop sensors, the primary current’s magnetic field is concentrated in a magnetically soft toroid. A Hall element that generates a voltage proportional to the magnetic field or to the current is positioned in the toroid’s air gap. The Hall voltage is amplified and delivers a mapping of the primary current as an output signal. One advantage of these sensors is the simple design. Closed-loop sensors have a design similar to that of direct sensors. The Hall voltage, however, is not used directly as a measurement signal; instead, it is used to regulate a secondary current. The secondary current flows through a coil with N windings and generates a magnetic compensation field in the toroid. If the secondary current × N is exactly the same as the primary current, the two magnetic fields cancel each other in the toroid. The Hall element always regulates the magnetic flux to zero. The secondary current is simultaneously the sensor’s output signal (Isec = Ipri/N). In the spectrum between -40 and +85°C, the accuracy and respectively the deviation are less than 1%.
Real-time current measurements Current sensors are electromechanical components that supply a precise mapping of the input and output currents in real time. These measurement signals are used for precisely driving the power semiconductors and for system monitoring. HARTING has developed an optimised solution that fulfils the requirements of modern power electronics. The new current sensor product family is based on the proven Hall Effect principle, where current is measured in an electrically isolated manner via its magnetic field. The two principles used in the products from HARTING are: ■ direct mapping current sensors (open loop technology) – used when the precision requirements are not that strict ■ compensation current sensors (closed loop technology) – available for demanding, high precision measurements.
(Top) Open-loop sensor, with simple design. (Bottom) Closed-loop sensor, with secondary current.
Further information
HARTING Technology Group www.harting.com
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