When a transformer is powered on, there is a humming sound primarily caused by the action of high magnetic flux. Under normal operation, the transformer's sound is uniform. If there are abnormal noises, it is crucial to carefully identify the causes and address them.
If the transformer's sound is louder than usual, with a uniform pitch, the following reasons may be considered:
(1) Overvoltage in the power grid: Overvoltage due to single-phase grounding or resonant overvoltage in the grid can increase the transformer's sound. In such cases, comprehensive judgment can be made by combining the indications on voltage meters.
(2) Overloading of the transformer: Overloading can result in a heavy "humming" sound. If the load exceeds the allowed normal overload value, the transformer load should be reduced according to on-site regulations.
If there are miscellaneous noises in the transformer:
It could be caused by the loosening of certain components on the transformer leading to vibrations. If there is a noticeable increase in transformer sound, and no significant abnormalities in current or voltage are observed, it might be due to the loosening of internal clamps or screws tightening the core, resulting in increased vibration of silicon steel sheets.
If the transformer produces discharge sounds:
"Crackling" discharge sounds may occur, especially during nighttime or rainy weather, accompanied by blue corona or sparks near the transformer bushing. This indicates severe contamination of insulators or poor contact in equipment lines. Internal discharge may result from electrostatic discharge in non-grounded components inter-turn discharge in coil windings, or improper contact in the tap changer.
If the transformer emits bursting sounds:
Bursting sounds suggest internal or surface insulation breakdown. The transformer should be immediately taken out of service for inspection.
If the transformer produces boiling sounds:
Boiling sounds, rapid temperature changes, and an increase in oil level indicate a short circuit in the transformer winding or severe overheating caused by poor contact in the tap changer. The transformer should be promptly taken out of service for inspection.
This analysis provides a professional perspective on the potential issues associated with transformer sounds.