Author: Mr. Jan-Rainer Sicham / Siemens AG / Power Transmission Division E T TR TLM RE

Abstract:

The world population of power transformers is aging. According to an investigation of the EIA of 2008, 10000 generator step-up transformers in the USA are between 10 and 60 years old. 2800 out of them are larger than 100 MVA. They form the most essential core of electricity transmission, but need to be replaced or overhauled in near future.

As manufacturing of transformers including tender and commissioning processes takes between 18 and 24 months, power utilities are looking for alternatives to buying new transformers.

The industry has responded to the requests by the development of different methods for life time extension, repair and retrofit of power transformers.

Siemens TLM, the transformer lifetime management business unit of Siemens, offers a wide range of options, including the so called “mobile workshop”, which “brings the transformer factory to site”.

We have exchanged complete sets of windings of power transformer on site, up to system voltage levels of 735 kV AC and +-500 kV HVDC

.

When using the most modern winding designs of Siemens compared to older designs of 1970 to 1980, the efficiency of power transformers can be increased. Siemens has achieved total loss reduction of power transformers of more than 8% due to the reduction of eddy losses of transformers. Thus the retrofit measure on power transformer even can be regarded as a “green method” of lifetime extension.