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Description / Abstract:
Introduction
The recommendations presented in this guide apply primarily to
modern large oilimmersed power transformers with high-voltage
windings rated 345 kV and above. This guide is a supplement to
ANSI/IEEE C57.12.11- 1980, Guide for Installation of Oil-Immersed
Transformers [ l ] ,1 which is basic to transformer
installation procedures. It is assumed that the reader is familiar
with the recommendations of ANSI/IEEE C57.12.11-1980.
The higher dielectric stresses required for extra-high-voltage
(EHV) transformers, combined with thermal problems arising from
their usually greater capacity, demand a high degree of care during
installation - much greater than transformers in the ratings
covered by ANSI/ IEEE C57.12.11-1980. Additional problems arise
from their large size which may, in the future, require site
assembly of major components. The relatively high investment in EHV
transformers and their importance to the power system demonstrates
the need for rigorous refinements in transformer preparation.
Generally, the user must conform to the transformer
manufacturer's minimum recommendations in order to obtain a
warranty. All manufacturers require greater care in preparation of
EHV transformers than for those of lower voltage. All manufacturers
require some degree of vacuum treatment before filling with oil,
specify the vacuum to be maintained during oil filling, and
recommend limits on residual moisture and gas content of oil and
dielectric strength of oil after filling. Limiting values for each
transformer will be supplied by the manufacturer. Only the general
order of magnitude of limits and the means required to reach these
values are covered in this guide.
1 Numbers in brackets correspond to those of the
references in Section 10.