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Reference

Maximum losses for distribution transformers on the EU market

The Tier 2 load and no load loss ceilings that three phase medium power transformers must meet, as set out in Regulation (EU) No 548/2014 as amended.

These tables set the legal ceiling, not a manufacturer's value. A transformer within their scope declares its own losses on its datasheet, and those losses must be at or below the ceiling for its rating and construction. Two units of the same rating from different manufacturers can declare different values below the same ceiling.

The tables apply to three phase medium power transformers with one winding at a highest voltage for equipment up to 24 kV and the other up to 3.6 kV, which covers the common 10, 11, 20 and 22 kV distribution systems with a low voltage secondary. Ratings that fall between two rows are obtained by linear interpolation, as footnote 1 to each table requires.

Table I.1, liquid immersed, Tier 2

Rated powerMaximum load losses PkMaximum no load losses P0Class
≤ 25 kVA600 W63 WAk, Ao − 10 %
50 kVA750 W81 WAk, Ao − 10 %
100 kVA1,250 W130 WAk, Ao − 10 %
160 kVA1,750 W189 WAk, Ao − 10 %
250 kVA2,350 W270 WAk, Ao − 10 %
315 kVA2,800 W324 WAk, Ao − 10 %
400 kVA3,250 W387 WAk, Ao − 10 %
500 kVA3,900 W459 WAk, Ao − 10 %
630 kVA4,600 W540 WAk, Ao − 10 %
800 kVA6,000 W585 WAk, Ao − 10 %
1000 kVA7,600 W693 WAk, Ao − 10 %
1250 kVA9,500 W855 WAk, Ao − 10 %
1600 kVA12,000 W1,080 WAk, Ao − 10 %
2000 kVA15,000 W1,305 WAk, Ao − 10 %
2500 kVA18,500 W1,575 WAk, Ao − 10 %
3150 kVA23,000 W1,980 WAk, Ao − 10 %

The first row applies to ratings up to and including 25 kVA.

Table I.2, dry type, Tier 2

Rated powerMaximum load losses PkMaximum no load losses P0Class
≤ 50 kVA1,500 W180 WAk, Ao − 10 %
100 kVA1,800 W252 WAk, Ao − 10 %
160 kVA2,600 W360 WAk, Ao − 10 %
250 kVA3,400 W468 WAk, Ao − 10 %
400 kVA4,500 W675 WAk, Ao − 10 %
630 kVA7,100 W990 WAk, Ao − 10 %
800 kVA8,000 W1,170 WAk, Ao − 10 %
1000 kVA9,000 W1,395 WAk, Ao − 10 %
1250 kVA11,000 W1,620 WAk, Ao − 10 %
1600 kVA13,000 W1,980 WAk, Ao − 10 %
2000 kVA16,000 W2,340 WAk, Ao − 10 %
2500 kVA19,000 W2,790 WAk, Ao − 10 %
3150 kVA22,000 W3,420 WAk, Ao − 10 %

The first row applies to ratings up to and including 50 kVA. The table has no 315 kVA or 500 kVA row, so those ratings are interpolated.

Where the tables are corrected or replaced

CaseWhat the regulation does
Primary at Um 36 kV, for example 33 kV systemsApplies correction factors from Table I.3a to the load and no load ceilings
Secondary above Um 3.6 kVApplies correction factors from Table I.3a
Dual voltage windings differing by more than 10 %Applies correction factors from Table I.3b, depending on how the dual voltage is rated
Liquid immersed pole mounted transformersUses its own table, Table I.6
Ratings above 3 150 kVASets a minimum Peak Efficiency Index instead of absolute ceilings

Correction factors are applied to the specific configuration and are confirmed per case rather than tabulated here.

Worked interpolation

RatingConstructionBetween rowsLoad losses PkNo load losses P0
200 kVALiquid immersed160 and 250 kVA2,017 W225 W
500 kVADry type400 and 630 kVA5,630 W812 W
315 kVADry type250 and 400 kVA3,877 W558 W

Linear interpolation between the adjacent table rows, rounded to the nearest watt.

What the regulation excludes

The regulation lists applications it does not cover, including instrument transformers and transformers specifically designed to provide a DC supply to electronic or rectifier loads. That DC exemption expressly does not extend to transformers intended to provide an AC supply from DC sources, such as those for wind turbine and photovoltaic applications, so those remain in scope.

Sources

SourceWhat was read
EUR-Lex, consolidated text CELEX 02014R0548-20191114Annex I, Tables I.1 to I.6, footnotes, and the scope exclusions
legislation.gov.ukThe same Tier 2 values for 630 to 2500 kVA, and the regulation's continued application in Great Britain

Read on 16 September 2026. Commission Regulation (EU) No 548/2014 as amended by (EU) 2019/1783.

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Daverlan Power Systems (2026). Maximum losses for distribution transformers on the EU market. https://daverlan.com/technical-resources/transformer-loss-limits/

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Related

Distribution transformers Dry type transformers Standards cross reference