Experimental Study on Internal and External Noise Characteristics of a 10kV Oil-immersed Transformer

This paper investigates the internal and external noise characteristics of a 10kV oil-immersed transformer based on advanced acoustic measuring technology. A kind of fibre-optic hydrophone is installed inside the transformer and four acoustic sensors are placed outside in the air. The noise is measured under the condition of no-load and short circle, and the amplitude and frequency characteristics are obtained. The results show that the amplitude of internal noise is higher and contains more high order harmonics when compared with the external noise. It means the internal noise has a higher signal noise ratio, and contains more information. These results can be used for further research such as transformer noise generating mechanism, transmission regulation, transformer noise controlling.