Shielding measures of power transformer to mitigate stray loss and hot spot through coupled 3D FEA

Abstract

Leakage flux generated in the power transformers cause stray losses in metallic parts of the transformer. Stray losses largely affect the transformer hot spot which leads to thermal failure. It is necessary to mitigate the impact of leakage flux on metallic parts by employing magnetic shunts and eddy current shields. Preeminently clamping structures like flitch plate and end frames experience substantial losses, hence combinations of shielding can be used for better loss reduction. In this study, a case study is performed on a 315 MVA, 420/27 kV single-phase generator power transformer. This work is based on coupled three-dimensional (3D) finite-element analysis (FEA) of the transformer model. A new type of magnetic shunt is explored; also different design combinations of shielding are specified in this work for efficient mitigation of hot spots as well as tank walls.

Keywords

• power transformers
• finite element analysis
• eddy currents
• magnetic shielding
• shielding measures
• stray loss mitigation
• coupled 3D FEA
• leakage flux
• metallic parts
• transformer hot spot
• thermal failure
• impact mitigation
• magnetic shunts
• eddy current shields
• clamping structures
• flitch plate
• single-phase generator power transformer
• coupled three-dimensional finite-element analysis
• 3D finite-element analysis
• apparent power 315 MVA
• voltage 450 kV
• voltage 27 kV