Experimental and Numerical Study on the Overall MeanNoise Level of CRT Transformers

CRT transformers may installed indoor adjacent to or near residential areas since they areclean and safe comparing to the conventional oil transformers. But noise discrepancy is intrinsicallyaccompanied with all types of transformers and of course CRT transformers. Minimizationof noise level has biological importance. It is known that the core of transformersis the main source of noise generation. In this paper experimental and numerical investigationis implemented for a large number of fabricated CRT transformers in Irantransfo Co. to evaluatethe effective parameters on the overall mean sound level of transformers. Noise Levelof each sample is measured according to IEC60651 criteria. Numerical simulation is done usingANSYS software. Pearson factor shows that there is a robust conjunction between firstnatural frequency and noise level of CRTs. To evaluate mean noise level of the transformersprior to fabrication in design phase, a correlation between the numerical and experimentalvalues is proposed in such a way that knowing dimensions of the core of the transformer andfirst natural frequency of the core as the main effective parameters, approximate value of themean noise level could be forecasted. Considering some simplifications and assumptions anovel two-condition equation is proposed for approximating mean noise level. According to the results and comparison with experimental values it can be deduced that the proposed equation could be used to approximate mean noise level in design phase prior to manufacturing with + -10% uncertainty tolerance.

Keywords:

experimental , FEM , mean noise level , CRT transformers