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Publications C802.3-15

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C802.3-15 - Minimum efficiency values for power transformers

Publication Year:

  • 2015

Total Pages:



  • CSA


This is the second edition of CSA C802.3, Minimum efficiency values for power transformers. It supersedes the first edition published in 2001, under the title Maximum Losses for Power Transformers, and it replaces the portion of CAN/CSA-C802, Maximum Losses for Distribution, Power, and Dry-Type Transformers, that pertains to power transformers. The portions of CAN/CSA-C802 pertaining to liquid-filled distribution transformers and dry-type transformers have been revised and incorporated into CSA C802.1,Minimum efficiency values for liquid-filled distribution transformers, and CAN/CSA-C802.2, Minimum efficiency values for dry-type transformers, respectively. CSA C802.1, CAN/CSA-C802.2, and CAN/CSA-C802.3 supersede CAN/CSA-C802.

Revisions made to this edition of C802.3 include a change in the efficiency assessment criteria from evaluating "maximum losses" to meeting "minimum efficiency" for power transformers.

CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of NRCan, BC Hydro, Manitoba Hydro, Hydro Quebec, Canadian Electricity Association, Ontario Ministry of Energy, and Independent Electricity System Operator (IESO).

CSA Group also acknowledges the contribution made by the Subcommittee on Transformer Efficiency, responsible for the development of CAN/CSA-C802, on the development of this Standard.


This Standard applies to all liquid-filled power transformers, except those types listed in Clause 1.3, and specifies minimum efficiency ratings. The minimum efficiencies specified are for transformers at their base kVA rating, as described in Tables 1 to 3. Minimum efficiencies are also specified for some special designs (Clause 4.3).

This Standard applies to power transformers rated from 501 to 10 000 kVA and operating with a 60 Hz waveform and does not include the effect of any harmonics.

Note: Transformers designed for harmonic environments are often called K factor transformers.

This Standard does not apply to autotransformers, grounding transformers, rectifier transformers, reactors, or any units which have load-tap-changing gear or tertiary windings.

In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.

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