R. Karthik

Enhancing the critical characteristics of natural esters with antioxidants for power transformer applications

The energy demand of the whole world is dominated by petroleum products for centuries in the field of critical application like electricity. The application of mineral oil in power system equipment like transformer is potentially hazardous to environment. The exploitation of petroleum oil is running out of demand and in the near future, oil scarcity exists. This work focuses in identifying alternate dielectric for replacing traditional mineral oil. India is a tropical country, which produces vegetable oils like sunflower oil, palm oil, coconut oil, mustard oil, corn oil, soybean oil and rice bran oil profusely and it can be used as dielectric fluids in transformer. To be more proficient in the operation of transformer, these vegetable oils should be converted in to superior dielectric fluids. This work also embraces the individual and combinatorial effect of selected natural and synthetic antioxidants in natural ester. For investigation sunflower oil, rice bran oil, soybean oil and corn oil are chosen. The critical parameters like breakdown voltage, viscosity, flash point and fire point are calculated according to IEC and ASTM standards before and after addition of antioxidants with vegetable oils. Astoundingly it is found that the use of natural and synthetic antioxidants can enhance the critical parameters of natural ester for transformer application and the antioxidant activity in the natural ester is discussed. The interpolation functions are calculated based on the results obtained in minimum and maximum concentration of antioxidant added. These functions are used to predict the intermediate output variations caused for each antioxidant concentrations (in gram).

Reclaiming aged transformer oil with activated bentonite and enhancing reclaimed and fresh transformer oils with antioxidants

Transformers are the vital units of power system and the major dielectric used in transformer is petroleum based mineral oil, which acts both as an insulating medium and potential coolant. This work focuses on reclaiming aged mineral oil using activated bentonite and enhancing the critical characteristics of reclaimed mineral oil and fresh transformer oil using antioxidants. The reclamation is carried by treating 500 ml aged mineral oil with 5 g activated bentonite quantity. Then the treated sample is mixed with different combinations of natural and synthetic antioxidants. The enhancement of fresh transformer oil is carried by adding multiple combinations of antioxidants with different mechanisms like free radical scavenging, metal chelating and synergism. The critical parameters like breakdown voltage, viscosity, flash point and fire point of the samples are calculated using ASTM and IEC specifications before and after adding antioxidants. The recorded parameters prove that the reclaimed aged mineral oil after added with high performance antioxidant combinations can perform superior than base fluids and can be reused in power transformers. Moreover the enhanced fresh transformer oil with antioxidants shows greater improvement and this technique could be possibly employed for reclamation (regenerating) and enhancement of waste insulating oils.

Investigations on Eco Friendly Insulating Fluids from Rapeseed and Pongamia Pinnata Oils for Power Transformer Applications

Transformer mineral oil which is normally hydrocarbon based is non- biodegradable and pollutes the environment in all aspects. Though vegetable oils are eco-friendly in nature and potentially could be used in transformers as a replacement for the mineral oil, there usage is restricted because of their oxidative instability. The present work focuses on using rapeseed oil and pongamia (pongamia pinnata) oil as effective alternatives for the traditional mineral oil in power transformer. The oxidative stability of the rapeseed oil and pongamia oil is increased by using combinations of the natural and synthetic anti-oxidants as additives. The parameters like breakdown voltage, viscosity, flash point, fire point are measured for the rapeseed oil and pongamia oil with and without the additives as per IEC and ASTM standards. The results shown encouraging changes in the parameter values and ensures the use of the oils as a potential alternative insulation in power transformers.

Enhancement of critical characteristics of aged transformer oil using regenerative additives

This work investigates the effect of critical properties on aged transformer oil with various additives such as semiconductive nanoparticles, natural and synthetic antioxidants. The additives are added with aged transformer oil in different fraction with the objective to enhance the critical properties of oil and eliminating hazardous disposal. The critical properties like breakdown voltage, flashpoint, firepoint and viscosity of the samples before and after treatment are measured according to IEC and ASTM standards. Impressively it is found that semiconductive nanoparticles, natural and synthetic antioxidants improve the critical properties of aged transformer oil to specified standard. The suitable fraction to which the sample shows constructive result is reported. In addition to that, the above treatment process can be implemented both in the sense of economic retreatment and environmental safety margin.

Enhancement of critical parameters of used transformer oil with naturally Activated Bentonite and investigation of vegetable oil performance with antioxidants

Transformers are the most vital components in power system. The common dielectrics used in transformers are solid, liquid and gaseous type. The major role of all the dielectrics is to provide sufficient insulation to the system to which it is used. Among them the function of liquid dielectric is to provide insulation and cooling. Traditionally mineral oil is used in transformer for decades and aged oils after life will be either recycled or sent to waste dump. Ageing reduces the critical properties of oil and either disposal causes environmental hazard. In this work, an attempt has been made to find an economic solution to enhance the aged transformer oil by treatment with acid Activated Bentonite. This paper reviews the properties of natural and synthetic antioxidants in vegetable oil which are the most significant active components that play an important role in reducing oxidation. Critical characteristics of oil such as Breakdown Voltage (BDV), viscosity, flashpoint and firepoint will be examined on aged transformer oil before and after treatment with Activated Bentonite. Based on the test results obtained, an economic solution is obtained and a recommendation is imparted to replace mineral oil with vegetable oil. This effort surely paves the way to green environment and postpones oil scarcity.

Deterioration of solid insulation for thermal degradation of transformer oil

Power transformers are the most vital components of power system. Insulation used in power transformers are of insulating fluids and solid insulation system like pressboard, Kraft paper. In this work an effort has been made to investigate the detoriation of solid insulation systems for thermal degradation of transformer oil. The aging degree of solid insulation system is examined through Atomic force Microscope (AFM), Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) techniques.

Enhancement of critical properties of pure and aged transformer oil using nanocomposites

Power Transformers are one of the most critical component of power system in which transformer oil is used for both insulation and cooling purposes. Mineral oil plays a vital role in insulation system of the transformer. In transformer, withstand strength of insulation materials mainly depends on the properties of the transformer oil. In this work, Semiconductive inorganic nanocomposites of ceramic type are chosen for this investigation of electrical and physical property of mineral oil (Transformer oil). Nanopowders of Zinc Oxide (ZnO), Aluminium Oxide (Al2O3) are combinedly added with the pure and aged transformer oil under various particle volume fractions to form nanocomposite fluids (NCFs). The electrical and physical properties like breakdown voltage, viscosity, flash point and fire point were measured at room temperature under ASTM and IEC standards. It was observed that breakdown voltage of pure and aged transformer oil shows improved results after the addition of nanocomposites with respect to increase in particle volume fractions.