David Hughes, head of ABB’s Power Products division in UK and Ireland, takes a look at the EU’s tightening ecodesign legislation and explains how ABB’s amorphous core dry-type transformers already exceed the energy efficiency demands for Tier 2 standards that will be introduced in 2020.
In June 2014, new ecodesign transformer regulations were passed by the European Commission (EC) that introduced new efficiency standards for small, medium and large power transformers used in electrical transmission distribution networks and industrial applications, including data centres.
It is part of the EC’s ecodesign legislation, which covers more than 40 types of product that use, generate, transfer or measure energy. The list includes house- hold appliances, refrigeration equipment, computers and industrial products.
The Commission estimates that the combined effect of all of the ecodesign minimum efficiency regulations will contribute around a third of its energy efficiency target, called the 20-20-20 target. This aims for a 20% reduction in greenhouse gas emissions, raising renewable energy consumption to 20% and improving energy efficiency by 20%.
The new legislation covering power distribution transformers comes into force in July 2015 and transformer operators are now reviewing and reacting to the new rules in preparation.
The legislation is phased and has the objective of preventing high-loss transformers from being installed in the UK. It is the first phase, known as Tier 1 that will come into force in July 2015 but it is only the start. By 2021 a Tier 2 standard will be introduced. It will demand transformer designs that are around 10% more energy efficient than Tier 1.
By eliminating the worst performing transformer models from 2020 onwards, the EC expects to see energy savings in the range of 16 terawatt hours (TWh) per year. That’s equal to around half the annual electricity consumption of Denmark and is equivalent to avoiding CO2 emissions of 3.7 million tonnes.
The detail of the legislation is complex, reflecting the market for transformers itself. It takes account of the MVA capacity and type of transformers as losses are inherently higher for some types of transformer than they are for others. And it’s worth noting that the legislation does not apply to all transformer products – for example, single phase transformers are not affected, whereas a Peak Energy Index (PEI) will apply to units above 3.15 MVA and larger power transformers. In addition, some types of transformers will be exempt due to their use or construction.
Substantial savings
Because large quantities of power pass through transformers, they account for a significant 30 – 40% of the losses in transmission and distribution systems. With this in mind, even a small increase in transformer efficiency can have a significant impact on energy losses and CO2 emissions.
Over an operation life than can exceed 30 years, even a marginal improvement in the efficiency of a transformer can result in substantial energy savings. And considering the size of Europe’s large and growing transformer fleet, the potential savings are huge.
The number of distribution transformers in the EU is growing from an estimated 3.6 million in 2011 to almost 4.7 million units by 2025, serving utilities as well as energy intensive industries such as data centres and railways, and also integrating renewable energy generation.
Design options
Designing transformers is a complex business. It’s possible to create numerous different designs that deliver the same duty, with each variation having a different build cost and a different efficiency based on the calculated losses in the core and the windings.
The result is that transformer designers need to have a solid understanding of the type of duty that a unit will experience in its lifetime. For example, if a transformer is lightly loaded for long intervals, the designer would need to take an approach that minimises no-load losses, whereas a transformer used in a data centre or another industrial setting that operates at or near full capacity constantly. A third approach is required for transformers that experience a combination of both, where load and no-load losses need to be balanced.
No-load losses are always present and constant and occur in the transformer’s core due to fluctuating magnetisation of the core (known as hysteresis loss) and eddy currents in the core. These losses occur as soon as the transformer is energised and do not alter as the load rises.
On the other hand load losses occur in a transformer’s conductors and increase quadratically with the load on the transformer. They are a result of ohmic loss and eddy currents. In the case of transformers used in energy-intensive industrial sectors such as data centres, load losses assume particularly high importance.
By understanding a transformer’s duty and selecting a suitable model, operators can select a transformer design that will meet the tightening standards of future legislation today and enjoy energy savings that reduce operating costs. ABB can help its customers make a head start in meeting the new regulations. It already has the advanced technology in hand that enables the production of highly efficient transformers that exceed the rigorous demands of the Tier 2 standard that will be introduced in 2021.
EcoDry transformers
The ultra-efficient EcoDry distribution transformer is such a solution. At its heart, the dry-type transformer has a low-loss amorphous core that has been well proven in liquid-filled transformers. It is available in ratings from 100 to 3,150 kVA with operating voltages of up to 36 kV.
EcoDry transformer models can save up to 70% of no-load losses and reduce load losses by 30%. Being dry-type transformers, the units offer all the practical advantages of their type, such as: no fire risk; no risk of escape of pollutants or fire-hazardous substances; long lifetime; high mechanical strength; ability to cope with load changes, overloads, sort-circuits and over-voltages; and reduced installation footprint.
The range includes three models, each of which is designed to meet the differing needs of applications where losses are either predominantly no-load losses, load losses or a combination of the two.
The EcoDry Basic is designed for power utilities, where a low load profile is typical in normal operation and no-load losses account for the major proportion of total losses. A second model is the EcoDry Ultra, which minimises both the no-load and load losses simultaneously, making it ideal for medium load situations, such as serving pumping or ventilation systems where two transformers operate together for redundancy.
Minimising load losses
But it’s the EcoDry 99plus that is of most relevance to data centre operators. It is designed for full-load efficiency and can operate at more than 99% efficiency. It is suited to industrial applications such as data centres, where plant operates at or near full capacity. Depending on the load profile and the life-cycle of the transformers involved, the annual savings on load losses can equal or even exceed the actual purchase costs.
In a typical data centre, an EcoDry99plus transformer rated at 1,000 kVA with 10,000 V primary voltage would reduce annual power losses by more than 30,000 kWh and cut CO2 emissions by around 18 tonnes per year.
This not only enhances the environmental performance but also enables operators to cut running costs.
Worldwide, ABB estimates that around 2% (or 25 GW) or all electricity generated is lost as a result of distribution transformer inefficiency. By reducing losses with products like EcoDry transformers can reduce overall losses, leading to energy savings, reduced operating costs and reduced emissions.
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