Frequently asked questions

Wilson Power Solutions as we know it today was established in 1946 by entrepreneur Richard Wilson, the business started out dealing in the provision of flame-proof equipment, pumps and motors. Now managed by the 3rd Generation, we have grown from a small family business to one of the industry’s most trusted power and distribution transformers manufacturers with almost 80 years' experience in the sector.

Our engineering, contracts, production, and quality teams are based at our headquarters in Leeds, West Yorkshire, whereas our Regional Sales Managers (RSMs) are based locally in the areas they serve. Our site team is deployed from our Leeds office to projects across the UK and Europe. You can find an area representative on our contact page by entering the first half of your postcode (e.g., LS11) into our interactive sales map.

Our standard stocked distribution transformer ratings are from 315kVA to 2500kVA. We offer smaller or larger transformers for bespoke requirements. Our power transformer offer goes up to 300MVA and 400kV, with the capacity to build Autotransformers at 500MVA.

Lead times vary based on the size and complexity of the transformer. Our standard distribution transformers (Wilson T2, Wilson e4 and Wilson d2) are available on short lead times as we hold a big stock on our site in Rodley. The lead time goes up if you require additional ancillaries or packaged switchgear and LV cabinets, depending on our production capacity at the time and supply chain lead times. Bespoke transformers and power transformers require longer lead times for the customised GA drawings, design sign off by the customer, dedicated procurement for parts, manufacturing and shipping. We are investing in new manufacturing facilities in the UK and India to remain competitive. Speak to our sales team for an accurate lead time depending on your project requirements.

The bulk of our business is conducted within the United Kingdom, and we service key customers in Europe. For overseas enquiries, please contact us for more details.

To ensure that your new transformer is the right fit, you must assess your load profile, voltage requirement, existing network details, climatic conditions, application or sector specifications, risks, potential network challenges, and any future expansion needs. Our technical team can help you select a suitable transformer for your project. We can give advice, but we do not hold design liabilities; we recommend hiring an HV consultant if needed.

Wilson Power Solutions holds ISO 9001, ISO14001, and ISO45001 certifications, which ensure our compliance with quality, environmental, health, and safety standards, respectively.

All of our transformers are manufactured to internationally recognised standards, including IEC 60076. They undergo rigorous testing as standard and come with a 24-month warranty from dispatch.

We used to refurbish transformers, but in 2021, we decided to stop supplying them. With our commitment to reach Net Zero by 2050, in line with BEAMA and the UK government, comes a huge responsibility to provide the market with efficient transformers to ensure our products’ operational carbon footprint (which makes up ~95% of the LCA) is as minimal as possible.

Our transformers are manufactured in our privately owned factory in Chennai, India. They are then brought to the UK, where they are tested, fitted with ancillaries, MV switchgear, and LV cabinets, painted, and shipped to customers. We supply Toshiba-manufactured iDNO unit-type transformers and EHV transformers. As Toshiba's exclusive partner in the UK, our experienced site team services Toshiba's DNO projects and installs power transformers in the UK and Europe.

Transformer loss requirements are governed by the European Commission Regulation (EU) No 548/2014, implementing Directive 2009/125/EC and Regulation (EU) 2019/1783 amendment. The UK government adopted Ecodesign after Brexit. Replacing Tier 1 (2015), Tier 2 Ecodesign requirements came into effect in 2021 for distribution and power transformers placed in the market or put into service within the UK. The regulation specifies distribution transformers' load and no-load loss values and a minimum peak efficiency index for power transformers.

Yes, manufacturers, importers, and distributors of transformers that sell in the United Kingdom and European Union must ensure compliance before placing products on the market within these regulated regions.

The ecodesign requirement applies only to new transformers placed on the market or put into service after the specified regulation dates. There are a few cases of exemptions and concessions from Tier 2, depending on the application or replacement restrictions. Please ask our team for more details.

Refurbished transformers that undergo a replacement of the magnetic core (or part of it) or a replacement of one or more of the complete windings require a reassessment for conformity and must comply with Tier 2 regulation.

Yes, there are three types of exceptions:

• Concessions include two cases: a. Installing distribution transformers in existing urban substation locations with space and weight constraints that affect the maximum size and weight of the replacement transformer to be used, and b. A new build or a replacement of power transformers related to disproportionate costs associated with their transportation and/or installation. Concessions require filling out a regulatory relief tool in the UK and submitting it to OPSS through us as a manufacturer.

• Exemptions: These are automatic exemptions that do not require notifying OPSS. They depend on the transformer's application, e.g., Earthing or Grounding Transformers, Instrument Transformers, Offshore Wind Turbine Transformers, Railway Transformers, Nuclear Transformers, Hire Transformers, and Traction Transformers.

• Corrections are applied to Ecodesign load and no-load losses for distribution transformers with special combinations of winding voltages and with dual voltage in one or both windings, differing by more than 10%.

No, there are different tables for load and no-load losses and minimum peak efficiency index requirements for both liquid-immersed and dry-type transformers. Cast resin transformers cannot achieve the same efficiency levels as oil-filled transformers. On average, and according to Ecodesign requirements, liquid-immersed transformers have 19% lower combined losses than dry-type transformers.

Compliance is determined using standardised test methods specified in international standards such as IEC 60076-20.

Yes, our experts can assist you in selecting the right transformer for your needs, ensuring full compliance with Ecodesign regulations.

The manufacturing of an amorphous core involves the rapid cooling (or quenching) of molten alloy steel to form a thin, non-crystalline, random molecular structure. This process helps maintain the material's amorphous state, which is essential for reducing magnetic losses. The core is typically made into thin sheets or ribbons that are stacked to form the transformer's core structure.

Yes, Wilson Power Solutions was the first to supply amorphous metal core transformers in the UK in 2008, with the first transformer sold in 2009. Our amorphous product range is in its third generation with Wilson e4 Ultimate Low Loss, an upgrade from Wilson e2 Super Low Loss and Wilson e3 Ultra Low Loss transformers.

Most transformers in the market have a Cold-Rolled Grain-Oriented Silicon Steel (CRGO) metal core, which has reached its full potential. Reducing losses further is difficult without incurring significantly higher costs.

Amorphous transformers combine amorphous core material with low current density conductors to provide the lowest combined transformer losses. Due to their high magnetic susceptibility, low coercivity, and high resistance, the combined core and winding losses are reduced to an average of 27% lower than those of Tier 2 (CRGO) compliant transformers.

Amorphous core transformers are particularly beneficial in industries prioritising energy efficiency, lower operational costs, and carbon reduction, such as hospitals, universities, renewable energy systems, and large-scale manufacturing. They are ideal for applications where transformers run continuously or under heavy load conditions, as their reduced core and winding losses translate into significant long-term energy, cost and carbon savings. Amorphous transformers are suitable for asset replacement projects as they exhibit great savings potential.

Amorphous cores exhibit lower no-load losses due to reduced hysteresis losses, as their random molecular structure generates less heat by limiting friction during magnetisation and demagnetisation. Furthermore, their laminations are roughly one-tenth the thickness of CRGO laminations, resulting in lower resistivity and eddy current losses.

Amorphous transformers can be added to existing electrical networks to replace ageing assets or extend the network. However, we need to ensure that the new amorphous transformers' vector grouping, impedance, and voltage ratios match those of the existing transformers on that network.

Our amorphous offer is for distribution transformers from 315kVA to 3000kVA with a standard voltage ratio of 11kV/415V, but we can offer our amorphous transformers up to 33kV if required.

Yes, our Wilson e4 was designed at a reduced secondary voltage (415V instead of 433V). In addition to the industry standard five tap options of the De-energised Tap Changer, Wilson features an extended tapping setting of +7.5% as a standard. To provide more responsive voltage regulation, we introduced Wilson e4+ Ultimate Low Loss Amorphous Transformer with a vacuum On-Load Tap Changer, which allows automatic voltage regulation without the need to de-energise the transformer. This OLTC has the capability of a 3-second gap between operations and can do up to 500,000 maintenance-free operations, which allows it to outlive the transformer. Being the smallest high-speed tap changes in the world, the OLTC has a wide regulation range, making it suitable for applications with irregular supply patterns, including random peaks and troughs.

Our amorphous transformers have been installed since 2009, with over 2000 installations across the UK and zero core failures. They are installed in various sectors, including supermarkets, hospitals, universities, manufacturing, ports, MOD, etc. Head to our downloads for case studies or our projects page and filter the product group by amorphous to view references.

The only differences are in radiators and tank sizes. Amorphous transformers up to 1250kVA do not have radiators, as the tank can sufficiently dissipate the heat. Amorphous transformers are larger than Tier 2 compliant transformers, offering higher efficiency. GA drawings can be found on our Transformer List page for more details. As far as maintaining amorphous transformers, they have the same maintenance schedule as standard CRGO transformers. Still, their reduced losses can lead to less wear and tear, potentially lowering maintenance costs.

Start by finding out the age of your existing transformer to understand its condition; maintenance logs could be helpful. Then, compare your current transformer energy losses to newer transformer energy losses (Tier 2 or amorphous). If the numbers indicate that you are running an inefficient transformer, look into options in the market to replace it.

We recommend considering three key factors when selecting a transformer:

1. Technical specifications – These should align with your existing network requirements, such as voltage ratios, parallel transformer vector groups, fault levels, and other network parameters.

2. Space and weight constraints – Higher-efficiency transformers typically come in larger and heavier tanks. To ensure compatibility with your site, we suggest referring to our GA (General Arrangement) drawings.

3. Future load requirements – Consider potential changes in demand. Some companies downsize after improving operational efficiency, while others may require a like-for-like replacement or an increased rating—especially if planning for additional loads like EV chargers or heat pumps.

You have two options: a Tier 2 compliant transformer, or our amorphous transformer range—the most energy-efficient in Europe. The amorphous models deliver maximum savings in energy, carbon emissions, and operating costs. While they may involve a slightly higher initial CAPEX, this is typically recovered within 2–3 years thanks to significantly lower OPEX.

Once the old transformer is removed, it should be disposed of responsibly. Service providers usually offer recycling and disposal services that comply with environmental regulations. This can help ensure that hazardous materials like oil and metals are handled safely. Moreover, over 90% of tranransformer components can be recycled or recovered which improves the circularity of this product.

Refurbishing old transformers can, in some cases, be a CAPEX cost-effective way to fix a problem. However, refurbishing transformers does not improve their efficiency. If your transformer was manufactured before 2015 (Ecodesign Tier 1), you are most likely running an inefficient transformer that wastes tens of MWh and thousands of pounds annually. Analysis of transformer life cycle assessment shows that 95% of carbon is emitted as losses during the operational phase, making the case for new build over refurbished transformers stronger, environmentally and financially (OPEX).

Most organisations' decision-makers might not be fully aware of the benefits of replacing transformer assets. Distribution transformers in the UK account for 25% of network losses and act as energy guzzlers. Operators or owners are often unaware of the energy waste of transformers (which happens 24/7, with or without load). Use our payback calculator or talk to our team to build a case, based on numbers showcasing potential energy, carbon and financial savings. You can strengthen your case if you showcase other considerations, for example, additional costs, such as installing transformers and inflated electricity rates to show real savings, schedule upgrades to ensure minimal disruption, and the importance of resilience and the costs transformer failures might cause.

All of our transformers are suitable for outdoor applications. Depending on the location of the project and the environmental considerations, we recommend some specifications over others. For example, C5 paint classification is preferred for coastal applications or harsh environments. Hermetically sealed transformers might be more suitable for industrial environments to protect the transformer oil from contamination. Bunds and filters might be required as a safety measure to protect water sources in the event of oil leakage. It's best to ask our technical team if in doubt.

Our transformers are liquid-immersed and ONAN (mineral oil filled) as a standard. We offer synthetic ester (MIDEL) or natural ester (FR3 vegetable oil) for applications that require transformers with higher ignition and fire points, providing extra protection. FR3 requires the transformers to be hermetically sealed, not free-breathing.

Free breathing systems allow air exchange, requiring regular maintenance, while hermetically sealed systems are fully enclosed, offering minimal maintenance and better contamination resistance.

An OLTC (On-Load Tap Changer) can adjust the tappings to ensure a constant secondary voltage while the transformer is energised and operational, making it suitable for dynamic environments. A DETC (De-Energised Tap Changer) requires the transformer to be turned off during adjustments, making it ideal for fixed or less variable applications.

Yes, OLTCs are highly compatible with renewable energy systems, as they can handle the dynamic fluctuations in voltage caused by variable energy generation (e.g., solar or wind power).

All of our power transformers are bespoke designed and manufactured. You can choose from our standard designs to reduce the time spent creating a design from scratch. We have an extensive list of stocked standard distribution transformers with multiple arrangements and efficiencies. These transformers are available on a shorter lead time than bespoke transformers. However, we offer many bespoke transformers to meet the project needs, from multiple windings and non-standard voltages to breathing types and different core materials. Talk to our team for more details.