Load sound power levels for specification purposes of three-phase 50 Hz and 60 Hz liquid-filled power transformers

In the industry there is an increasing awareness observed that load sound, depending on transformer parameters and loading, contributes to, and may even dominate the total sound level of a transformer in service. This results in a growing tendency to specify the permissible sound level not only for no-load operation, but also for the loaded transformer when purchasing new transformers.

Specifying a realistic load sound level for power transformers is often challenging due to limited availability of reliable and validated information. This easily leads to physically unrealistic load sound level specifications, either unnecessary high, e.g. NEMA TR 1 standard, or, as has been a trend in recent years, unachievable low without using external sound mitigation measures.

To provide guidance…