Not sure what this is supposed to mean. The only google refs for 'opposition method' in conjunction with IEC 60076 all point to a paper written by (presumably) native Spanish speakers, so it may be a mistranslation.

IEC 60076 generally deals with temperature testing and rating of power transofrmers, and Section 2 deals specifically with temperature testing, but it is not clear what testing methods are specified there (if any).

refs:

http://webstore.iec.ch/webstore/webstore.nsf/artnum/035347

(IEC webstore; click Preview to view a PDF preview of the document (table of contents, foreword, etc.)



Titre du document / Document title
A moisture-in-oil Model for power Transformer monitoring-Part II: Experimental verification
Auteur(s) / Author(s)
GARCIA Belén (1) ; BURGOS Juan Carlos (1) ; ALONSO Angel Matias (2) ; SANZ Javier (1) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Universidad Carlos III de Madrid, Leganés, Madrid 28911, ESPAGNE
(2) Department of Electrical Engineering, Polytechnic University of Madrid, Madrid, ESPAGNE
Résumé / Abstract
In the companion paper, a model to detect failures leading to an increase of the water content in transformer oil was proposed. In this paper, the experimental verification of the Model is presented. The Model was tested in a 1500-kVA test transformer constructed as a reduced scale model of a 60-MVA 220-kV transformer. In order to load the Transformer to have the capability of varying load and power factor over a wide range, the opposition method described in IEC 60076-2 Standard was used. Sensors to measure temperature and moisture in oil were installed in the Test Transformer. The Model was adjusted and validated using a set of data corresponding to different operating conditions. The Transformer was submitted to an accelerated aging process studying the Model response in such a case. In order to verify the Model's ability to detect failures, a water ingress in the Transformer was simulated.
Revue / Journal Title
IEEE transactions on power delivery (IEEE trans. power deliv.) ISSN 0885-8977 CODEN ITPDE5
http://cat.inist.fr/?aModele=afficheN&cpsidt=16659535