scope:

This document is applicable to three-phase and single-phase liquid immersed subsea power transformers (including auto transformers) with at least one winding with rated voltages in the range 3,6 ≤ U_m ≤ 245 kV and with rated power in the range 50 kVA to 300 MVA. The intention is to specify additional requirements that are not covered by IEC 60076 series and ANSI/IEEE C57.12 series.

Subsea transformers designed and tested in accordance with this document shall fulfil both IEC 60076 and ANSI/IEEE C57.12 series with respect to performance and testing. In order to achieve this, the following philosophy has been used:

• Rated power shall be established (verified by testing) both in accordance with IEC and IEEE definitions. Only one figure (based on IEC or IEEE) shall however be on the rating plate, this shall be specified by purchaser in the contract.

• The most stringent design and test requirements are specified in this document, ensuring that both IEC and IEEE requirements are met.

For subsea transformers where no winding has a rated voltage above or equal to 3,6 kV, this standard may be applicable, either as a whole or in part.

The mechanical design principles are also applicable for liquid-immersed reactors.

Where the terms "subsea transformer" or "transformer" are used, this shall mean Transformer Assembly. Where required, it is stated whether transformer accessories like penetrators and connectors are included or not.