IEEE DRAFT C57.110 : D7 FEB 98

1. Overview
   1.1 Scope
   1.2 Purpose
   1.3 References
   1.4 Definitions
   1.5 Letter Symbols
2. General Considerations
   2.1 Transformer losses
       2.1.1 Harmonic current effect on PR loss
       2.1.2 Harmonic current effect of P EC
       2.1.3 Harmonic current effect on P OSL
   2.2 Transformer capability Equivalent
   2.3 Basic data
   2.4 Transformer Per unit losses
   2.5 Transformer losses at measured currents
   2.6 Harmonic loss factor for winding eddy currents
   2.7 Harmonic loss factor for other stray losses
3. Design considerations for new transformer specification
   3.1 Harmonic current filtering
   3.2 Impact on the neutral
   3.3 Power factor correction equipment
   3.4 Electrostatic ground shields
   3.5 Design consideration outside the windings
   3.6 Harmonic spectrum analysismonic currents
   3.7 Design consideration in the windings
4. Recommended procedures for evaluating the load capability of existing transformer
   4.1 Transformer capability equivalent calculation using design eddy current loss data
   4.2 Transformer capability equivalent calculation using data available from certified test report
   4.3 Neutral Bus capability for nonsinusoidal load currents
ANNEXES
   Annex A Bibliography
   Annex B Comparison of underwriters laboratory inc.
   Annex C Temperature Rise testing procedures (informative)
   Annex D Tutorial Discussion of Transformer losses and the effect of har

Applies to two types of transformers covered by IEEE C57.12.01-19xx and C57.12.00-19xx and NEMA ST20. It is not applicable to rectifer transformers.