For more than 60 years, Hitzinger has been providing three-phase generators for hydropower and other applications from its primary location in Linz, Austria.

 

Not least thanks to their technological maturity, alternators from the long-standing Upper Austrian manufacturer are regarded as unsurpassable on the power generation market. We asked Ing. Helmut Roland which philosophy and what formula for success drive the engineers. The experienced mechanical engineer has been dealing with generator design for 36 years, heading Hitzinger’s R&D department for several decades. In an extensive interview, Roland provided us with an interesting insight of the world truly committed designers of electromechanical equipment.

Mr. Roland, if you were to build a power station for yourself, what would the ideal generator be like?
Roland: I would first of all ask myself what it should be capable of and then have it designed and built by Hitzinger to these requirements. What the ideal generator needs to do is to best fulfil customers’ requirements.

Which questions and requirements are at the top of the list?
Roland: Naturally, efficiency and dissipation are of the essence, but this is not all there is to it by far. I have to ask myself how the generator will be operated. To answer this question, as the operator I of course need to know the hydrograph curve. This is supplemented by questions like “Are noise emissions an issue?”, “Is mechanical robustness playing a main role?”, “Can shock propagation occur?”, “or maybe floods?”. And there can be several more.

This means generators are tailor-made for each customer?
Roland: Absolutely. In our factory, you will not find a generator not showing a customer ID. We do not have an anonymous production. We build generators from scratch, from magnetic dimensioning to the insulation system to the suitable iron to copper ratio. It is part of our company’s philosophy to address the questions and suggestions of customers during the planning phase, to counsel them and finally supply them with a machine that keeps them satisfied for decades.

Does that mean that suggestions from customers can prompt further development of generators?
Roland: This is exactly what this means. We frequently see impulses from practical operation trigger designs. I would even say that most suggestions are market-driven. One thing should not be forgotten: Innovations in mechanical design usually are usually not the result of a stroke of genius but basically requires intense communication.

Where else do suggestions for further development of Hitzinger generators come from?
Roland: First of all, there is maintenance and repair. I frequently visit repair shops to see what issues they are confronted with. Also, old generators from the 1930es and 1940es are particularly interesting. Looking at old windings, you see that the engineers of the time have spent an incredible lot of thought within the given possibilities. There is a lot to be learned from them, even though especially in the materials field there has been a lot of progress. But there had been quite good material in the past as well.

What about now: Are you increasingly using newly developed material?
Roland: We are rather open-minded but very conservative when it comes to application. New materials require laborious, intensive testing and analysis. We only use what has passed and fulfils our expectations 100 percent. You need to differentiate: We are looking intensely at the polyester materials used. Although there are standards, guidelines and accelerated ageing tests, it is impossible to determine exactly how long such a plastic will ultimately last. At the windings, we have been using high-grade insulation materials for some time that result in various improvements. The sheets already come with numerous options. We enjoy the benefits of co-operation with Linz-based manufacturer, voestalpine. They supply state-of-the-art high performance steels low in loss and at the same time high in durability and performance.

What exactly does this mean?
Roland: This means that we buy only steel grades with full temperature stability. The same is true for the coating material used. This allows pyrolysis at 450 to 500° C for maintenance or repair without thinking twice. The organic material in the winding system is dissolved completely while the sheet metal and its coating remain unharmed. This quality of steel also allows utilization of thinner sheets. This reduces losses and results in higher yields for customers.

This presumably also requires close co-operation with the suppliers?
Roland: Absolutely. We attempt to co-operate with all our vendors as closely as possible. This means that not only vendors come to us to deal with the issues and challenges of our production but that I am also most welcome at all times to visit the development teams of these companies to contribute my suggestions. In this way, many interesting new aspects come our way over time.

Efficiency levels are very high already. Are there still attempts to add the occasional tenth of a percent more?
Roland: As a matter of course, this remains an issue. It is part of our philosophy. Basically, though, our efficiency levels are internationally very competitive. In my 36-year career with Hitzinger, I have not seen a single generator not fulfilling its efficiency rating.

Which screws remain to be turned to further increase efficiency?
Roland: I think that the magnetic steel sheets are key. Still, the question needs to be answered in which area the efficiency should be raised. During partial load or during full load, depending on in which mode the generator is operating most of the time. Any improvement should maximise the overall yield for the operator. For good reasons, in bids for tender published by major power companies, every working point of the machine is reviewed. They often include specifications for many details such as the copper to iron ratio, excitation or various material issues.

Do you have an advantage working for this kind of customers?
Roland: We love working with customers who challenge us to the full. For me, there is nothing quite like discussing a generator with all its details with experts from TIWAG, EVN, KELAG or other utilities. Even in initial talks, frequently details are discussed like how the cooling vents should be designed, how the sheet packets should be pressed or which electrical sheet or coating should be used. It is our satisfaction, after all, to see the customer’s satisfaction with the generator.

How is Hitzinger reducing the electromagnetic noise?
Roland: From a calculation and measurement point of view, this is a highly complex and difficult issue. This is why we rely on a close co-operation with the Linz University. The Austrian Center for Competence in Mechatronics (ACCM) utilises state of the art methods to measure noise emissions, providing us with a complete noise profile of our generators. This would otherwise exceed our capabilities.

Among the quality features of a synchronous generator is its high-speed performance. How can a manufacturer ensure this?
Roland: It is essential for this to take the mechanics into account as early as the basic magnetic cut. There is a lot that can be done in the rotor’s geometry. We have a number of design variants up our sleeves like whether or not to use a notch radius or additional pole supports. The design principles of the pole supports or corner reinforcement wedges we have developed are automatically entered to our calculation software.

Is the resin also a factor?
Roland: Absolutely. We use a specific resin for the rotors and another for the stators. To achieve best possible reliability, we have performed countless performance and cracking tests in all conceivable temperatures. We also tested many different insulations on the wires and filtered out the optimum. These aspects are not even added to our rated safety tolerances, they are really an additional unquoted safety buffer.

Hitzinger has successfully expanded its portfolio to include larger equipment rated up to 4 MVA. Did this require major efforts in design work?
Roland: It was really more difficult than it would appear. In mechanics, the effects of twice the mass are by no means proportional but grow exponentially. Fortunately, though, we can rely on our excellent engineers who deliver outstanding calculations especially with regards to vibrations, structural integrity or bearing dimensions. All parameters are finally entered to software we have been developing over several decades for the purpose.

Can you tell me some more about this calculation software?
Roland: This programme is not for sale in any software shop. Over several decades, we have been successively developing and more and more refining it. We calculate the mechanical and electrical characteristics of every single generator. Within seconds, the software runs a multitude of algorithms and modules largely developed in-house with specifications and exclusion criteria, etc., returning a design specification that can be used as is. Many envy us for this software. It was adapted such that it can be used by sales to show customers realistic designs following a few parameter entries. It is also relevant for turbine manufacturers, as we can use it for dimensioning the entire drive train provided the runner is overhung-mounted on the shaft. This is a powerful tool.

Hitzinger also supplies generators for ships to customers around the globe. Would you say that some of the expertise there can be transferred to hydropower applications?
Roland: Of course. Look at vibrations, for example: For a mine sweeper, it is vital to keep vibrations at a minimum. We were able to cross-transfer quite some knowhow. In marine and offshore applications, you often find extreme operating conditions requiring a high quality level. We were able to use some of our experience for the longevity of or hydropower generators. Or take the issue of sea water: Getting in touch with salt water, which can happen from time to time, should not be a problem for a Hitzinger generator.

Have you been able to profit from Hitzinger’s experience with diesel-electric locomotives?
Roland: Absolutely! Many of our railway generators work in places with a particularly hot or cold climate. We have supplied equipment for Russia, where auxiliary heaters were undesired but the engine is required to start anew with no problems such as broken insulation after a night with ambient temperatures dropping to -40° C. We have already been able to utilize this knowhow in hydropower generators.

Which areas of generator design have undergone the greatest changes in recent years?
Roland: This was clearly in the conditions for mains parallel operation. Smart Grids is the buzzword. They are supposed to meet the challenges posed by power feed from volatile forms of energy such as wind and solar. This is why nowadays the generators in use in hydropower plants are expected to contribute to keeping grids stable. In case of a mains short-circuit, for example, immediate disconnection is no longer accepted. Instead, the excess current must continue to be supplied to the grid so it can be rebuilt. Grid operators can specify how much active power and how much reactive power a generator may supply to the grid. The regulations for this have been around for some time but they are not strictly executed everywhere yet. This will come, and our generators are designed to meet these requirements.

Are you offering consulting services for your customers addressing these complex issues?
Roland: Yes we do and this is very important as well, as requirements for mains parallel operation differ greatly from country to country. Additionally, there are primary European guidelines that need to be taken into account. Each generator we build for any customer meets these new requirements and is ready for possible upgrading.

Can older generators be upgraded?
Roland: Not in all cases. Older models need to be operated using the old mode of operation. It will be necessary to discuss with grid operators how and how long this will be possible.

Are you maintaining a comprehensive documentation archive?
Roland: Yes, of course. We have a dedicated department for this. We frequently receive enquiries from repair shops for specific information, design worksheets or winding details of older generators. Usually this is not a problem even for generators that are 30 or 40 years old.

Does Hitzinger outside of the well-known synchronous generators also produce asynchronous generators or even permanent magnet generators for hydropower applications?
Roland: Yes, we have already built asynchronous generators. They have great efficiency values but can only be used in low power applications and are difficult to regulate. Consequently, demand is rather low. We have also produced permanent magnetic generators for tests but have left this technological path again. Given the current state of things, we have doubts that it will prevail. It cannot be ruled out, though, that this technology will possibly gain in importance in the future.

Hitzinger ships to customers around the globe. Does this high degree of internationality come with additional challenges?
Roland: No, for us the required voltage level or other electrical characteristics of a generator or its corrosion protection are just details like all others, as we build every single generator to order.

Are you seeing potentials for improvement?
Roland: I see opportunities for improvement on a daily basis, especially if I include the numerous requests and suggestions arriving every day. We have great pleasure if we are confronted with special requirements and issues and can fulfil them. We have no catalogue of generators from which to choose the appropriate one. We are keen on dealing with the customer’s questions so we finally find the perfect product for them. This philosophy has brought us to the point at which we stand today. For this, communication is key.