Power Transformers: ESPR Requirements, Existing Ecodesign Rules, Dielectric Oil Disclosure, and DPP Compliance Guide
Power transformers are already subject to EU ecodesign requirements under Commission Regulation (EU) 2014/548, which sets minimum efficiency tiers (Tier 1 and Tier 2) for no-load and load losses. The ESPR delegated act will add a Digital Product Passport requirement with recycled copper and steel content, dielectric oil type, and carbon footprint. Transformers are critical infrastructure components with lifetimes of 30–40 years.
Existing Ecodesign Requirements for Power Transformers
Tier
In Force Since
Scope
Key Requirement
Tier 1
1 July 2015
Medium power transformers 1–3,150 kVA
Maximum no-load and load losses per rated power class
Tier 2
1 July 2021
Medium power transformers 1–3,150 kVA
Stricter maximum no-load and load losses (approximately 15% improvement over Tier 1)
Truth Anchor: Commission Regulation (EU) 2014/548 remains in force under ESPR Article 74. Power transformers must meet Tier 2 efficiency requirements from 1 July 2021. — EUR-Lex CELEX:32024R1781
Expected DPP Data Fields for Power Transformers
Data Field
Annex III Category
Status
Efficiency tier (Tier 1/Tier 2)
Energy performance
Already required
No-load losses (W)
Energy performance
Already required
Load losses at 100% load (W)
Energy performance
Already required
Rated power (kVA)
Product identifier
Already required
Dielectric oil type
Substances of concern
New under ESPR delegated act
PCB content (legacy transformers)
Substances of concern
New under ESPR delegated act
Recycled copper content
Recycled content
New under ESPR delegated act
Recycled GOES steel content
Recycled content
New under ESPR delegated act
Carbon footprint per kVA
Carbon footprint
New under ESPR delegated act
Expected lifetime (years)
Durability and reliability
New under ESPR delegated act
The Long Lifetime Challenge for Transformer DPPs
Power transformers have expected lifetimes of 30–40 years. ESPR requires DPP data to remain accessible for the product’s lifetime plus 10 years. For a transformer installed in 2027 with a 40-year lifetime, the DPP data must remain accessible until 2077 — 50 years from now. This is the most extreme URL persistence requirement in the ESPR framework.
Transformer manufacturers must select DPP registry service providers with credible long-term data persistence guarantees. Self-hosted DPP systems are particularly risky for transformers — a manufacturer that ceases operations in 2040 cannot guarantee DPP data availability until 2077. Registry service providers with contractual data persistence guarantees and data portability provisions are the appropriate solution for transformer DPPs.
What Transformer Manufacturers Must Do Now
Verify compliance with existing Regulation (EU) 2014/548 Tier 2: Confirm all transformers meet Tier 2 no-load and load loss limits.
Audit dielectric oil type: Document the dielectric oil type (mineral oil, ester oil, silicone oil) for all transformer models. Confirm absence of PCBs.
Audit recycled copper and GOES steel content: Determine recycled content percentages for copper windings and grain-oriented electrical steel core laminations.
Select DPP registry with long-term persistence: Given the 50-year DPP data retention requirement, select a registry service provider with credible long-term data persistence guarantees.
Conduct lifecycle carbon footprint assessment: Calculate the carbon footprint of transformer models. Focus on manufacturing phase (copper, steel production) and use phase (no-load losses over 40-year lifetime).
Transformers Under ESPR: Power Distribution Efficiency
Power transformers are critical components of electricity distribution networks. They operate continuously for 30-40 years and their efficiency has a significant impact on electricity network losses. The EU has been regulating transformer efficiency since 2014, and the current Ecodesign Regulation for power transformers (Regulation (EU) 2019/1783) sets minimum efficiency requirements. The ESPR transformer delegated act will add the Digital Product Passport requirement and new data fields for recycled content and substances of concern.
Rated power (kVA), rated voltage (kV), rated frequency (Hz)
Existing
Insulating fluid
Fluid type (mineral oil, ester), PCB-free declaration, biodegradability
Existing + ESPR
Recycled content
Recycled copper %, recycled steel (core) %
New (ESPR Annex III)
Carbon footprint
CO2e per kWh of electricity transformed (lifetime)
New (ESPR Annex III)
Substances of concern
PCB declaration, SF6 (if applicable), lead in solder
New (ESPR Annex III)
Lifetime
Expected lifetime (years), insulation class, thermal class
New (ESPR Annex III)
PCB-Free Compliance and Legacy Transformers
Polychlorinated biphenyls (PCBs) were widely used as insulating fluids in transformers until they were banned in the 1980s. However, many legacy transformers containing PCBs are still in service in EU electricity networks. The ESPR transformer DPP will require manufacturers to declare that their transformers are PCB-free. Network operators who still have PCB-containing transformers in service should plan for their replacement as part of their ESPR compliance strategy.
Transformers Under Existing Ecodesign Regulation
Power transformers in the EU are subject to Ecodesign requirements under Regulation (EU) 548/2014, which sets minimum efficiency requirements for small, medium, and large power transformers. The regulation uses the CENELEC standard HD 538 S1 as the reference for transformer efficiency classes — Tier 1 (in force from 2015) and Tier 2 (in force from 2021). The ESPR delegated act for transformers will extend these requirements to include Digital Product Passport obligations and will likely introduce requirements for distribution transformers used in renewable energy applications, including offshore wind and solar farm transformers that are not currently covered by EU 548/2014.
What Transformer Data Must the DPP Contain?
The ESPR delegated act for transformers will require DPPs that include: product identifier and manufacturer details, rated power in kVA, primary and secondary voltage ratings, frequency (50 Hz or 60 Hz), no-load losses in watts (P0), load losses at rated current in watts (Pk), short-circuit impedance percentage (uk%), efficiency class (Tier 1 or Tier 2 under EU 548/2014), insulation class, cooling type (ONAN, ONAF, OFAF, etc.), insulating fluid type (mineral oil, ester fluid, dry-type), PCB content declaration (polychlorinated biphenyls — a legacy issue for older transformers), carbon footprint per unit, and end-of-life recycling instructions for the insulating fluid and core materials.
Amorphous Core Transformers and ESPR Efficiency
Amorphous metal core transformers offer significantly lower no-load losses than conventional silicon steel core transformers — typically 70–80% lower no-load losses. This makes them highly attractive for applications where transformers operate continuously at low load, such as distribution transformers in residential and commercial networks. The ESPR delegated act for transformers is expected to incentivise the adoption of amorphous core technology by setting no-load loss limits that can only be met by amorphous core or equivalent high-efficiency core materials. Manufacturers of conventional silicon steel core transformers should assess whether their products will meet the expected ESPR Tier 3 requirements and begin product development work on amorphous core alternatives.
Yes. Commission Regulation (EU) 2014/548 sets minimum energy efficiency requirements for power transformers. These requirements entered into force on 1 July 2015 and remain in force under ESPR Article 74. Transformers must meet minimum efficiency tiers (Tier 1 and Tier 2).
The ESPR delegated act for transformers is expected in 2027-2029. From the compliance date, every power transformer placed on the EU market must have a valid DPP.
Commission Regulation (EU) 2014/548 defines two efficiency tiers. Tier 1 (in force since 1 July 2015) sets minimum no-load and load losses. Tier 2 (in force since 1 July 2021) sets stricter limits. Transformers must meet the applicable tier based on their rated power and voltage class.
The delegated act is expected to require disclosure of recycled copper content (windings), recycled steel content (core laminations), and recycled aluminium content (where used). Transformer cores contain significant quantities of grain-oriented electrical steel (GOES), which has a high recycled content rate.
Oil-filled transformers use dielectric oil for insulation and cooling. The DPP is expected to require disclosure of the oil type (mineral oil, ester oil, silicone oil) and any PCB content (legacy transformers). PCB-containing transformers are banned from the EU market.
Register Your Digital Product Passport
The EU DPP Registry goes live on 19 July 2026. EU customs will verify DPP compliance automatically from that date. Products without a valid DPP can be refused entry. Register now at Africa’s first ESPR-compliant DPP registry.
Power transformers are currently subject to ecodesign requirements under EU Regulation 548/2014, which sets minimum energy efficiency requirements for power transformers with a minimum power rating of 1 kVA. The regulation sets maximum no-load loss and load loss values for different transformer types and sizes. The ESPR delegated act for transformers will build on these requirements and add DPP data disclosure requirements, particularly for transformer fluid (oil) composition and end-of-life handling.
Transformers are long-lived assets — the typical lifespan of a power transformer is 30–40 years. This means that transformers installed today will still be in service in 2055–2065, well beyond the EU's 2050 net-zero target. The ESPR DPP for transformers will provide the data needed to manage transformers over their long lifespan, including information on the transformer fluid (which may be mineral oil, natural ester, or synthetic ester), the transformer's efficiency class, and the transformer's expected remaining useful life. This data is valuable for grid operators and industrial users who need to plan transformer replacement programmes.
Frequently Asked Questions
The ESPR delegated act for transformers is expected to be adopted in 2025–2027, superseding EU Regulation 548/2014. Manufacturers should plan for compliance by 2027–2029. The existing regulation remains in force until the ESPR delegated act takes effect.
EU Regulation 548/2014 covers medium power transformers (1 kVA to 3,150 kVA) and large power transformers (above 3,150 kVA). The ESPR delegated act is expected to maintain this scope and may extend coverage to small transformers (below 1 kVA) that are not currently covered.
The DPP for transformers is expected to include: the type of transformer fluid (mineral oil, natural ester, synthetic ester); the volume of fluid; the fluid's fire point; the fluid's biodegradability; and instructions for safe handling and disposal at end-of-life. Mineral oil transformers require special handling at end-of-life due to the risk of PCB contamination in older transformers.
PCBs (polychlorinated biphenyls) were used as transformer fluids until they were banned in the 1980s. Some older transformers may still contain PCB-contaminated oil. The ESPR DPP for transformers will not apply to transformers already in service, but it will require new transformers to disclose their fluid composition to prevent future PCB contamination issues.
The ESPR delegated act is expected to tighten the minimum efficiency requirements for transformers, potentially requiring Tier 2 efficiency (as defined in EU Regulation 548/2014) as the minimum for a wider range of transformers. The delegated act may also introduce requirements for amorphous core transformers, which have significantly lower no-load losses than conventional silicon steel core transformers.