What is an amorphous core transformer?
An Amorphous Core Transformers (AMT) is an extremely energy-efficient transformer that is used in electric grids. Amorphous Core Transformers are also recognised for being much more environmentally friendly than ‘traditional’ transformers because of their very high efficiency and excellent recyclability.
- In conventional transformers, the core contains silicon steel laminations, all with a near uniform crystalline composition that is stacked in its structure.
- In amorphous core transformers (ironically, the word “amorphous” means “without a clearly defined shape or form, which are generally the same in physical structure, a ribbon of amorphous metal is wound around to make the core in a rectangular structure making it more resistant to short-circuit stresses.
Transformers in use
When it comes to energy infrastructure, transformers have a habit of not being taken into serious consideration. They are workhorses that simply ‘sit there and do their job’, day-in, day-out. However, with many transformers now reaching their end of life, it is a prescription for potential failure that could very seriously disrupt a site’s ability to function should a transformer fail.
Energy costs are exerting increasing pressure on businesses, forcing them to look for savings to survive. A 25-year-old transformer not only wastes significant energy but can also threaten the business’s power supply. While upgrading or replacing a transformer may be a considerable investment, the potential energy savings, as well as the prevention of sudden transformer and consequent power failure, could avoid expensive downtime.
Advantages of amorphous core transformers:
Amorphous alloys have far better electrical characteristics compared to conventional ones.
The main benefit of using an amorphous transformer rather than a conventional one is that amorphous steel has much lower hysteresis losses. In layman’s terms, this means that far less energy is lost as heat during its operation when magnetisation and de-magnetisation of the core occurs. Amorphous alloys are also more reliable as they are made up of ferromagnets (ferromagnets have the characteristic where certain electrically uncharged materials strongly attract others).
With its non-crystalline structure and the random arrangement of atoms, it produces high resistivity yet provides low magnetic fields with minimal energy loss.
The no-load loss (the magnetising current needed to operate the transformer that never varies and is “always on” – by always, that is 24 hours a day and 365 days a year- irrespective of the workload being put onto the transformer, whether ‘working’ or ‘idle’) is one quarter to a third that of traditionally cored steel transformers, so there is an immediate cost benefit to the business. This is also a result of the core being on average 75% of the size of a traditional core for the same electrical throughput.
Eddy currents (closed loop flows within conductors) are lower because the core thickness is some one tenth the thickness of traditional steel cores.
Other advantages in brief:
- Better overload capacity
- Excellent short circuit capacity
- High reliability
- Increased energy efficiency
- Lower maintenance cost
- Reduction in SO2 waste
- Reduction in fossil fuel consumption
- Savings on accumulated energy costs with cost-saving benefits to the business
- Transformer lifetime is increased
Environmental considerations
It is of vital importance that the industry helps to protect and maintain the environment. With stand-by (idle) losses reduced by up to 70% and on-load (working) losses reduced by up to 30% compared to traditional transformers, their contribution to helping the environment is obvious.
The environmental impact is lower because temperatures within amorphous steel cores are low and thus greatly reduce the amount of CO2 released into the atmosphere.
Therefore, amorphous transformers provide a twofold benefit:
- Helping towards safeguarding the environment
- Energy saving provides a reduction in bottom-line business costs
Challenges and other considerations
Some care does have to be taken with amorphous transformers. This is mainly because amorphous metal is brittle and has to be treated with care. It is susceptible to mechanical stress so cannot be sited where there might be vibrations, as this can cause small fragments of amorphous metals to break off (this cannot be repaired) and degrade the performance of the transformer.
Care also needs to be taken where there may be other existing infrastructure shortcomings such as a potential for short-circuits or step-loads. The rectangular shape of the core has a lower resistance to short-circuit fault, and the resistance to overload is lower than that of traditional transformers.
Amorphous transformers are a little more noisy than traditional transformers, so location has to be considered.
Amorphous core transformers are usually heavier than traditional transformers, so the extra weight when being installed has to be factored in.
A brief timeline of amorphous core transformer development
1957 – Amorphous metals were first created at the California Institute of Technology by Belgian-born materials scientist, Pol Duwez.
1976 – Charles Graham and Howard Liebermann of the University of Pennsylvania found a method of manufacturing amorphous metals commercially. They coined the name Metglas.
1979 – The first amorphous transformer, rated at 15kVA, was manufactured.
1990s – New amorphous metal alloys, cast into metal moulds, were developed with much lower cooling rates.
2004 – Researchers succeeded in producing amorphous steel in bulk, paving the way for better commercial availability.
2015 – The Eco Regulation 548/2014, known as “The Tier 1 Requirements” was introduced that demanded better load-losses and improvements in energy efficiency. This was also aimed at reducing CO2 emissions and thus improving environmental implications.
2021 – Tier 2 requirements with new Eco Regulation’s were introduced where the minimum energy performance standards for transformers were increased. Amorphous transformers far exceeds the minimum load losses to meet these new Eco Regulations.
