Influence of test method and gas pressure on negative lightning impulse breakdown voltage in ultra-pure water

Abstract Malaysia is the 2nd largest in palm oil export, and after overcoming economic age (average 25 years), the palm oil trees entail to replace usually. Therefore, a massive quantity of palm oil trunk biomass, containing a significant amount of starch, is available as bio-waste annually. The efficient extraction of this starch (carbohydrate polymer) would be worthwhile concerning the environment, economy, conversion of biowaste to bioresources, and waste dumping challenges. Central composite design executed an experimental model design, evaluated the impacts of process variables and their interaction through response surface methodology to optimize the novel bisulfite steeping method for starch synthesis. Design-Expert software performed the data analysis. The developed quadratic models for four factors (Strength of Sodium bisulfite solution, steeping hour, mixing ratio with the bisulfite solution and ultra-pure water) and one response (%Yield), demonstrated that a significant starch yield (13.54%) is achievable utilizing 0.74% bisulfite solution, 5.6 steeping hours, for 1.6 and 0.6 mixing ratio with the bisulfite solution and ultra-pure water respectively. Experimental outcomes were quite consistent with the predicted model, which eventually sustains the significance of this method. Malvern Zetasizer test revealed a bimodal granular distribution for starch, with 7.15µm of hydrodynamic size. Starch morphology was determined by scanning electron microscopy. X-ray diffraction investigation exhibits an A-type model, specifying persistent characteristics of extracted starch.

Download Full-text

Lightning Impulse Breakdown Voltage of Rice Bran Oil for Transformer Application

Energies ◽

10.3390/en14165084 ◽

2021 ◽

Vol 14 (16) ◽

pp. 5084

Author(s):

Mardhiah Hayati Abdul Hamid ◽

Mohd Taufiq Ishak ◽

Nur Sabrina Suhaimi ◽

Jaafar Adnan ◽

Nazrul Fariq Makmor ◽

...

Keyword(s):

Weibull Distribution ◽

Electric Fields ◽

Breakdown Voltage ◽

Rice Bran ◽

Rice Bran Oil ◽

Transformer Oil ◽

Uniform Field ◽

Testing Methods ◽

Lightning Impulse ◽

The Difference

Transformer oil does not only serve as an insulating liquid, but also in removing heat from the windings and cores. Mineral oil (MO) has been widely used in transformers for more than 150 years. Recently, researchers have attempted to search for alternative insulating oils due to the possibility that MO will run out in the future together with the concern on fire safety and environmental pollution. Among the potential oils is rice bran oil (RBO). This work presents the studies of the lightning impulse (LI) of RBO behavior under various electric fields, gap distances and testing methods. The electrical performances of LI tests show that RBO and Palm Oil (PO) have lower LI breakdown voltage than MO under both uniform and non-uniform electric fields. However, the difference in LI breakdown voltages between RBO, PO and MO are slightly small which is less than 20%. In addition, there is no significant effect in the various testing methods under both uniform field and non-uniform field where the percentages of difference are less than 12% and 8% respectively. The data of LI breakdown voltage were statistically analysed to predict the withstand voltage and 50% breakdown voltage of oil samples by using Weibull distribution. The Weibull distribution of MO, PO and RBO has well fit with the fitting line. Finally, the relationship between LI voltages under a non-uniform field with various parameters of PO and RBO was obtained and proposed. From this work, it can be concluded that RBO shows promising results to be considered as an alternative to MO in transformer applications.

Download Full-text