The magnitude of the main magnetic flux in a transformer core is determined by the excitation current. Since the no-load current of a transformer actually varies with its operating voltage, a higher voltage results in a larger no-load current, which in turn increases the excitation current. Conversely, a lower voltage leads to a smaller no-load current. Read More

a. Flare and form one end of the rivet. The flared thickness should be 2.3-3 mm, with a diameter of Φ13.5-14 mm. b. Place the processed silicon steel sheets onto the dedicated fixture for stacking. Trim the core laminations during the stacking process, ensure they are perpendicular to the base plane, and prevent any eccentricity. c. After the core stacking is complete and clamped tightly with a pressure plate, measure the stacking thickness to ensure it meets the drawing requirements. d. Fit the rivets with washers, insulating spacers, and insulating sleeves, then flare and form them. Ensure that the tightness of all installed rivets is consistent. Read More

The primary source of transformer noise is the core. Core noise is caused by core vibration resulting from the magnetostriction of silicon steel sheets and magnetic attractive forces. The magnitude of magnetostriction is related to the material of the silicon steel sheets and the tightness of the core; the higher the magnetic flux density of the core, the greater the magnetostriction of the silicon steel sheets. The condition of the stacking joints in the transformer core affects the flow of magnetic flux, causing the core to generate noise of varying degrees and magnitudes. If the AC power supply contains harmonic components, it will lead to increased noise. The fundamental frequency of core noise is twice the power supply frequency, along with noise at various integer multiples of that frequency. Additionally, electromagnetic forces between winding conductors or between coils can also cause vibration and lead to noise. The following are several countermeasures for suppressing noise: Read More