News

The main reasons for the abnormal noises of oil-immersed transformer

Release time:

Apr 02,2025

Source:

Nanyang Xinte Electrical Co., Ltd.

The main reasons for the abnormal noises of oil-immersed transformers are as follows:

I Electromagnetic aspects

1.Core problems

①Insulation damage between silicon steel sheets: Under normal circumstances, there is an insulating layer between the silicon steel sheets. If the insulation is damaged, it will lead to an increase in the eddy current of the core, intensify the vibration of the silicon steel sheets, and generate abnormal noises.

②Poor grounding of the core: The core must have good grounding. If the grounding is poor, a floating potential will be generated, triggering a discharge phenomenon and producing a "crackling" sound.

③Loosening of the through bolts: The through bolts are used to fix the core. If they are loose, the pressure between the silicon steel sheets of the core will be uneven, resulting in an increase in local vibration and generating abnormal sounds.

2.Winding problems

Inter-turn short circuit of the winding: If the inter-turn insulation of the winding is damaged, a short-circuit loop current will be formed, causing the winding to heat up. At the same time, abnormal electromagnetic forces will be generated, making the winding vibrate and emit sounds.

Poor contact of the winding: If the contact resistance at the connection part of the winding is too large, local overheating will occur during operation, causing thermal deformation of the surrounding insulating materials and generating a discharge sound at the same time.

II Mechanical aspects

1.Cooling device failures

①Fan failure: Problems such as unbalanced fan blades and damaged fan motor bearings will cause the fan to vibrate and generate noise during operation. This kind of noise is usually periodic and changes with the change of the fan speed.

②Oil pump failure: Wear of the oil pump impeller, failure of the oil pump motor, etc. will make the operation of the oil pump unstable, generating vibration and noise. The noise generated by an oil pump failure is generally dull and may be accompanied by abnormal oil pressure.

2.Loosening of components of the transformer body

①Loosening of the casing: Long-term operation of the transformer may cause the fixing bolts of the casing to loosen. Under the action of electromagnetic force and mechanical vibration, the casing will vibrate and make sounds.

②Loosening of internal components: For example, the fixing of components such as the tap changer and the leads is loose, which will cause collision and friction sounds due to electromagnetic force and vibration during the operation of the transformer.

III Other aspects

1.Oil quality problems

①Presence of impurities or water in the oil: It will reduce the insulation performance of the oil, cause local discharge, and produce a "hissing" or "crackling" sound.

②Low oil level: Exposing the winding above the oil surface will lead to a decrease in insulation and may also cause internal discharge, generating abnormal noises.

2.Influence of the external environment

①External short-circuit fault: When an external short-circuit occurs in the transformer, the short-circuit current will make the transformer bear huge electromagnetic force, leading to winding deformation, core displacement, etc., and generating abnormal noises.

②Lightning overvoltage: The overvoltage generated by lightning strikes will make the internal insulation of the transformer bear huge pressure, which may lead to insulation breakdown, discharge and other phenomena, generating a strong noise.

Keywords:

Power Transformer,Electrical transformer,Oil-Immersed Transformer,oil filled transformer,oil transformer,Three Phase Oil-Immersed Transformer,Three Phase Transformer

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