Minimum efficiency values for power transformers
|Publication Date:||1 January 2015|
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.