Thermodynamic equilibrium of transformer oil-paper insulation — An experimental study

2016 ◽  
Author(s):  
S. K. Ojha ◽  
P. Purkait ◽  
S. Chakravorti
Keyword(s):  
Experimental Study ◽  
Thermodynamic Equilibrium ◽  
Transformer Oil ◽  
Paper Insulation

An Experimental Study of Free Corrective Heat Transfer in a Parallelogrammic Enclosure

1983 ◽  
Vol 105 (3) ◽  
pp. 433-439 ◽  
Author(s):  
N. Seki ◽  
S. Fukusako ◽  
A. Yamaguchi
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Nusselt Number ◽  
Correlation Equation ◽  
Transformer Oil ◽  
Experimental Measurements ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Prandtl Numbers ◽  
Rayleigh Numbers

Experimental measurements are presented for free convective heat transfer across a parallelogrammic enclosure with the various tilt angles of parallel upper and lower walls insulated. The experiments covered a range of Rayleigh numbers between 3.4 × 104 and 8.6 × 107, and Prandtl numbers between 0.70 and 480. Those also covered the tilt angles of the parallel insulated walls with respect to the horizontal, φ, of 0, ±25, ±45, ±60, and ±70 deg under an aspect ratio of H/W = 1.44. The fluids used were air, transformer oil, and water. It was found that the heat transfer coefficients for φ = −70 deg were decreased to be about 1/18 times those for φ = 0 deg. Experimental results are given as plots of the Nusselt number versus the Rayleigh number. A correlation equation is given for the Nusselt number, Nu, as a function of φ, Pr, and Ra.

Oil and Paper Insulation for DC Converter Transformer

2017 ◽  
pp. 194-231
Keyword(s):  
Surface Charge ◽  
Electric Fields ◽  
Power Flow ◽  
Heat Transfer Process ◽  
Transformer Oil ◽  
Polarity Reversal ◽  
Bulk Property ◽  
Hvdc System ◽  
Direct Fluorination ◽  
Paper Insulation

Transformer oil and oil-impregnated paper, serve as the essential parts of converter transformer, suffering various electric fields. The accumulation of surface charge on the paper would lead to flashover. When the power flow of the HVDC system is reversed, the charge field will easily lead to discharge. Direct-fluorination is a method which could affect the material property without alternating the bulk property. Besides, a new type of nano-modified transformer oil is a method to improve properties. This chapter presents a study of the effect of fluorination on surface charge behavior, the effect of polarity reversal voltages on interface charge behavior and the effect of Boron nitride (BN) nanoparticles on the high thermal conductivity of transformer oil. Results show that fluorination had an influence on the chemical property of the paper and BN nanoparticles has improvements in heat transfer process. In the polarity reversal test, the dissipation rate becomes smaller as the reversal time gets longer.

On evaluation of thermophysical properties of transformer oil-based nanofluids: A comprehensive modeling and experimental study

2020 ◽  
Vol 300 ◽  
pp. 112249 ◽  
Author(s):  
Ahmadreza Ghaffarkhah ◽  
Masoud Afrand ◽  
Mohsen Talebkeikhah ◽  
Ali Akbari Sehat ◽  
Mostafa Keshavarz Moraveji ◽  
...  
Keyword(s):  
Experimental Study ◽  
Thermophysical Properties ◽  
Transformer Oil ◽  
Comprehensive Modeling
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