Transformers made of amorphous alloys: between theory and workshop 

OhTransformers made of amorphous alloyseveryone talks with delight - fantastic no-load losses, a revolution in energy. But in practice, working with them, you understand: the potential is really huge, but between the alloy ingot and the working transformer at the substation there is a huge gap filled with technological nuances that are often not mentioned in articles. Many people believe that the main problem is the fragility of the tape. This is true, but this is just the tip of the iceberg. The real headache comes later - during core assembly, heat treatment and, critically, integration into a real power system with its voltage surges, harmonics and mechanical loads.

Core: not just wound and forgotten

Working with amorphous tape for transformers made of amorphous alloys requires a completely different production culture. I remember our first attempts to wind a core for a prototype: a tape approximately 25 microns thick. Any burr on the technological equipment or the slightest overtightening during winding - and a microcrack immediately appears, causing a local disruption of the amorphous structure. Then it is not surprising why losses in finished products vary from batch to batch. The conveyor rollers, guides, and even the gasket material had to be completely redesigned to eliminate these defects.

And heat treatment... It's not like electrical steel. Here the temperature and holding time are sacred. It overheated by ten degrees - crystallization began, and that’s it, the benefits of losses can be thrown away. Insufficiently warmed up - residual mechanical stresses in the tape will then come back with increased buzzing. We found our regime, in general, by trial and error. One batch of cores even went to waste - the customer later complained about abnormal noise in a certain load range. We figured it out - the unstable vacuum in the furnace during annealing was to blame.

Another important point concerns the core design forTransformers made of amorphous alloys. Due to the fragility of the amorphous tape, classic butt structures with tape cutting are not the optimal solution. Most often, the winding path of a split core is chosen or complex stepped end structures are used - this allows minimizing the paths of magnetic flux closure. This approach increases the complexity of production, but ensures the stability of the operational characteristics of the transformer.

In practice: where does it really hit the spot?

In theory, efficiency increases, losses fall - beauty. But the economics of the project always arises as a question. For a typical distribution transformer in a city where the load is stable and high, the payback due to energy savings can take years. Another thing is specific objects.

For example, solar parks or wind turbines. There, transformers often operate in partial load mode, under a large number of harmonics from the inverters. This is where the low no-load losses of an amorphous core are not just a number in a catalog, but real savings over the entire service life. For just one such project in the Krasnodar region, we supplied complete transformer substations withtransformers made of amorphous alloys. The customer initially had doubts and considered it an expensive “bells and whistles”. A year later, they sent gratitude - the figures for consumption for the substation’s own needs pleasantly surprised them.

Or night modes in networks with sharply variable loads. When the transformer hangs idle for most of the day or with minimal load, the savings become noticeable. But again, we must consider not only the cost of active materials, but also the full life cycle.

Integration into the system: problems that were not expected

But this is perhaps the most valuable section, about which few people write. You made an ideal core with record low losses. Assembled the transformer. And then his life begins on the real network.

The first is resistance to short circuit currents. The mechanical strength of the amorphous core is lower. During a short circuit, enormous electrodynamic forces arise. If the active part and the fastening system are not calculated with a multiple margin, you can get displacement of the tapes, local overheating and, as a result, degradation of properties. It is necessary to strengthen the bandages and introduce additional elements of rigidity, which again adds weight and cost.

The second is acoustic noise. Due to the magnetostriction characteristics of an amorphous tape, the noise spectrum may shift to a more unpleasant area for perception. If the transformer is located next to housing, this can become a problem. The fight against noise is a different story: vibration-isolating platforms, special tank coatings, design optimization. It doesn't always work out the first time.

And third is maintainability. With an ordinary transformer everything is more or less clear. With amorphous it’s more difficult. Damaging the core when disassembling to repair the windings is as easy as shelling pears. Therefore, installation is often carried out at facilities where high reliability and minimal risks of emergency situations requiring opening of the active part are predicted.

Case from Wenzhou Qiaonasen Electrical Equipment LLC: not only sell, but also adapt

In our practice, inWenzhou Qiaonasen Electrical Equipment Co.,Ltd, was a demonstration project. We received a request for an energy-efficient transformer to modernize the network of a country village. It was necessary to reduce commercial losses. They proposed an option with an amorphous core. But the local network company expressed concerns about operation in conditions of frequent lightning surges and possible current surges.

We didn't just shipTransformers made of amorphous alloysfrom the factory. We had to hold a whole mini-seminar for the customer’s technical specialists: show calculations of the electrodynamic resistance of our specific model, provide data on tests for resistance to impulse effects. Moreover, together with their relay protection service, they adjusted the protection settings - this is necessary, because the amorphous core is saturated differently than the classic one, and this can affect the operation of differential protection.

As a result, transformers (More information about the company's solutions can be found here) have been operating successfully for three years now. The customer is satisfied with the reduction in losses, and we have gained invaluable experience in adapting a high-tech product to the specific, sometimes conservative, conditions of Russian networks. The company's specialization in solutions for the transmission and distribution of high and low voltage allows it to approach the issue comprehensively, and not just “sell hardware”.

Looking to the future: where to go?

The current trend is not towards a total transition toTransformers made of amorphous alloys, but on their reasonable use in hybrid structures. For example, combined cores, where part is made of an amorphous alloy to reduce no-load losses, and the other is made of high-silicon steel to improve performance under load. This approach may be the optimal compromise between cost and energy efficiency.

Much work is also being done with tape coatings that increase its mechanical resistance and corrosion resistance. If we can make serious progress here, many technological restrictions will be lifted.

And the main thing is digitalization. Embedding sensors for online condition monitoringTransformers made of amorphous alloys: vibration, local heating of the core. This allows you to not only hope for the longevity of the equipment, but also manage its resource and predict the need for maintenance. For critical facilities where such equipment is installed, this is a logical next step. The technology of amorphous alloys ceases to be exotic and becomes one of the tools in the engineer’s arsenal - a tool that requires careful and competent handling.