1.1 Scope and object
This Standard applies to power transformers complying with the series of GB 1094 and GB 6450, etc.
It is intended to provide information to users about:
— Certain fundamental service characteristics of different transformer connections and magnetic circuit designs, with particular reference to zero-sequence phenomena;
— System fault currents in transformers with YNynd and similar connections;
— Parallel operation of transformers, calculation of voltage drop or rise under load, and calculation of load loss for three-winding load combinations;
— Selection of rated quantities and tapping quantities at the time of purchase, based on prospective loading cases;
— Application of transformers of conventional design to convertor loading;
— Measuring technique and accuracy in loss measurement.
Part of the information is of a general nature and applicable to all sizes of power transformers.
Several chapters, however, deal with aspects and problems which are of the interest only for the specification and utilization of large high-voltage units.
The recommendations are not mandatory and do not in themselves constitute specification requirements.
Information concerning loadability of power transformers is given in GB/T 15164, for oil-immersed transformers, and GB/T 17211, for dry-type transformers.
Guidance for impulse testing of power transformers is given in GB/T 7449.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this Standard. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent edition of the normative documents indicated below.
GB/T 13499-2002 The following standards are cited：
