EU Transformer Loss Limits | Tier 2 Tables for 25 to 3150 kVA

These tables set the legal ceiling, not a manufacturer's value. A transformer in scope declares its own losses on its datasheet, 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, Um, up to 24 kV and the other up to 3.6 kV. That covers the common 10, 11, 20 and 22 kV distribution systems with a low voltage secondary. A rating between two rows is found by linear interpolation, as footnote 1 to each table requires.

Table I.1, liquid immersed, Tier 2

Rated power	Maximum load losses Pk	Maximum no load losses P0	Class
≤ 25 kVA	600 W	63 W	Ak, Ao − 10 %
50 kVA	750 W	81 W	Ak, Ao − 10 %
100 kVA	1,250 W	130 W	Ak, Ao − 10 %
160 kVA	1,750 W	189 W	Ak, Ao − 10 %
250 kVA	2,350 W	270 W	Ak, Ao − 10 %
315 kVA	2,800 W	324 W	Ak, Ao − 10 %
400 kVA	3,250 W	387 W	Ak, Ao − 10 %
500 kVA	3,900 W	459 W	Ak, Ao − 10 %
630 kVA	4,600 W	540 W	Ak, Ao − 10 %
800 kVA	6,000 W	585 W	Ak, Ao − 10 %
1000 kVA	7,600 W	693 W	Ak, Ao − 10 %
1250 kVA	9,500 W	855 W	Ak, Ao − 10 %
1600 kVA	12,000 W	1,080 W	Ak, Ao − 10 %
2000 kVA	15,000 W	1,305 W	Ak, Ao − 10 %
2500 kVA	18,500 W	1,575 W	Ak, Ao − 10 %
3150 kVA	23,000 W	1,980 W	Ak, Ao − 10 %

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

Table I.2, dry type, Tier 2

Rated power	Maximum load losses Pk	Maximum no load losses P0	Class
≤ 50 kVA	1,500 W	180 W	Ak, Ao − 10 %
100 kVA	1,800 W	252 W	Ak, Ao − 10 %
160 kVA	2,600 W	360 W	Ak, Ao − 10 %
250 kVA	3,400 W	468 W	Ak, Ao − 10 %
400 kVA	4,500 W	675 W	Ak, Ao − 10 %
630 kVA	7,100 W	990 W	Ak, Ao − 10 %
800 kVA	8,000 W	1,170 W	Ak, Ao − 10 %
1000 kVA	9,000 W	1,395 W	Ak, Ao − 10 %
1250 kVA	11,000 W	1,620 W	Ak, Ao − 10 %
1600 kVA	13,000 W	1,980 W	Ak, Ao − 10 %
2000 kVA	16,000 W	2,340 W	Ak, Ao − 10 %
2500 kVA	19,000 W	2,790 W	Ak, Ao − 10 %
3150 kVA	22,000 W	3,420 W	Ak, 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

Case	What the regulation does
Primary at Um 36 kV, for example 33 kV systems	Applies correction factors from Table I.3a to the load and no load ceilings
Secondary above Um 3.6 kV	Applies 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 transformers	Uses its own table, Table I.6
Ratings above 3 150 kVA	Sets a minimum Peak Efficiency Index instead of absolute ceilings

Each correction factor depends on the exact configuration, so it is read from Table I.3a or I.3b for the case in hand.

Worked interpolation

Rating	Construction	Between rows	Load losses Pk	No load losses P0
200 kVA	Liquid immersed	160 and 250 kVA	2,017 W	225 W
500 kVA	Dry type	400 and 630 kVA	5,630 W	812 W
315 kVA	Dry type	250 and 400 kVA	3,877 W	558 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 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. Those stay in scope.

Sources

Source	What was read
EUR-Lex, consolidated text CELEX 02014R0548-20191114	Annex I, Tables I.1 to I.6, footnotes, and the scope exclusions
legislation.gov.uk	The 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.

How to cite

Cite as

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

Licence

Creative Commons Attribution 4.0 International, CC BY 4.0

The data may be reused, redistributed and built on, including commercially, provided the source is credited.

Permanent address

https://daverlan.com/technical-resources/transformer-loss-limits/

This address does not change. Where the figures are revised the page is versioned and the address stays as it is.

EU loss limits for distribution transformers