Abstract Considering the nonlinear and non-stationary characteristics of transformer vibration acceleration signal obtained from surface tank, variational mode decomposition (VMD) theory is introduced. Simulation analysis shows that VMD has obvious advantages over EMD when needle frequency similar to signal. It effectively avoids two types modal aliasing over-decomposition, accurately reflects ...

This paper presents a highly efficient InGaP/GaAs HBT power amplifier (PA) implemented using proposed high- Q single- and two-winding transformer. A transformer is designed with printed circuit board (PCB) to combine the output reduced passive loss. Compared typical 1:2 transformer, an additional unit connected at mid-point of secondary winding construct single-winding without windings. An IMD3...

Many industrial and commercial sensitive loads are subject to the voltage sags and interruptions. The static transfer switch (STS) based on the thyristors is applied to improve the power quality and reliability. However, the transfer will result in severe inrush current in the load transformer, because of the DC component in the magnetic flux generated in the transfer process. The inrush curren...

At Siemens the in-house CFD code UniFlow is used to analyse fluid flow and heat transfer in oilimmersed dry-type transformers, as well transformer components like windings, cores, tank walls, radiators. It can be employed perform steady state transient analyses. This paper describes its physical models numerical solution methods. Moreover, it presents an application a valve winding of HVDC tran...