Understand the source of dry transformer noise

single phase pole mounted transformers body noise mainly silicon steel sheet magnetostrictive caused by the core vibration, silicon steel sheet joints and laminated magnetic leakage caused by leakage between the core, winding vibration, dry-type transformers. 1, the silicon steel sheet magnetostrictive noise caused by the core excitation, the direction along the magnetic field lines of silicon steel sheet size changes, and perpendicular to the size of the magnetic flux direction of the opposite changes occur. Magnetostriction causes the core to periodically vibrate as the excitation frequency changes. Since the magnetostrictive change cycle is half the power cycle, the core noise caused by magnetostriction is based on twice the power frequency. Due to the non-linearity of the core magnetostriction and the length of the magnetic flux path along the inner frame of the core, the core noise includes noise of the higher harmonic spectrum in addition to the fundamental frequency. 2, the electromagnetic noise caused by the core of silicon steel sheet at the seams and laminated between the magnetic flux leakage caused by magnetic attraction, which caused the core vibration. Because of the continuous improvement in core stacking, the core vibration caused by the electromagnetic attraction between the seams and the laminations is much smaller than the core vibration due to magnetostriction, so this noise is usually negligible. 3, magnetic flux leakage caused by winding vibration noise load current leakage current will cause the winding vibration. When the polemounted transformers rated working magnetic flux density in the 1.5 ~ 1.8T range. This vibration is very small compared to the core vibration caused by magnetostriction. But the load current leakage magnetic noise is proportional to the square of the load current, so the rated flux density of the transformer reduced to 1.4T when the following; winding vibration and silicon steel sheet magnetostriction caused by the core vibration connected.