An experimental study on the effects of DBDS in transformer oil of power transformers

2012 ◽  
Author(s):  
Faheem Ahmed Khan ◽  
J. Sundara Rajan ◽  
Mohd. Z. A. Ansari ◽  
Shahsadi Asra P
Keyword(s):  
Experimental Study ◽  
Transformer Oil ◽  
Power Transformers

scholarly journals Predicting the influence of the non-sinusoidal network mode on power transformers

2019 ◽  
Vol 114 ◽  
pp. 04005
Author(s):  
Ngo Van Cuong ◽  
Lidiia I. Kovernikova
Keyword(s):  
Service Life ◽  
Electric Power ◽  
Power Quality ◽  
Electrical Equipment ◽  
Operating Conditions ◽  
Transformer Oil ◽  
Power Transformers ◽  
Electrical Network ◽  
Electrical Networks ◽  
Current Harmonics

The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.

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.

Thermal Behavior of Power Transformers Filled With Waste Vegetable Oil-Based Biodiesel Under Dynamic Load

2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Ehsan Ebrahimnia-Bajestan ◽  
Hani Tiznobaik ◽  
Paul Gheorghe ◽  
Mohammad Arjmand
Keyword(s):  
Heat Flux ◽  
Ambient Temperature ◽  
Vegetable Oil ◽  
Dynamic Load ◽  
Renewable Resource ◽  
High Heat ◽  
Transformer Oil ◽  
Power Transformers ◽  
High Heat Flux ◽  
Aging Rate

Abstract Petroleum-based oils are widely used as electrically insulating materials in high voltage power transformers for dissipating high generated heat flux and maintaining the temperature below critical values. The operating temperature of a transformer dominantly governs its aging rate. In the present research, a renewable coolant as a versatile substitution for the petroleum-based oils was investigated to be employed in the cooling of transformers. The studied coolant is a vegetable-based oil extracted from the waste cooking oils. A numerical model was developed to follow the instantaneous changes in the load profile and ambient temperature and predict the instantaneous hotspot temperature values in the transformer under dynamic load. Then, this thermal model was used to explore the capability of the studied vegetable oil in the cooling of transformers compared with conventional transformer oil. The realistic ambient temperature and loading profile, as well as thermal properties of oils and characteristics of a transformer, were applied as the model’s inputs. The aging rate of the transformer in the presence of vegetable oil was also compared with the conventional transformer oil. The results indicate a better cooling performance for the vegetable-based oil, where a hotspot temperature reduction of 3 °C was observed in comparison to the petroleum-based oil. Also, the model predicts a significantly longer life for the insulating system of the transformer when the proposed vegetable-based oil is employed. The results of this research suggest a sustainable way of reusing the waste of a renewable resource as an alternative insulating liquid for the cooling of high heat flux electric/electronic devices.

Oil health index calculation and incipient fault diagnosis in power transformers using fuzzy logic

2022 ◽  
Vol 64 (1) ◽  
pp. 28-37
Author(s):  
T Manoj ◽  
C Ranga
Keyword(s):  
Fuzzy Logic ◽  
Logic Model ◽  
Transformer Oil ◽  
Power Transformers ◽  
Dissolved Gases ◽  
Health Index ◽  
Fuzzy Logic Model ◽  
Proposed Model ◽  
Incipient Faults ◽  
Incipient Fault

In this paper, a new fuzzy logic (FL) model is proposed for assessing the health status of power transformers. In addition, the detection of incipient faults is achieved where two or more faults exist simultaneously. The process is carried out by integrating a fuzzy logic model with the conventional International Electric Committee (IEC) ratio codes method. As transformer oil insulation deteriorates, excess percentages of dissolved gases such as hydrogen, methane, ethane, acetylene and ethylene are induced within the trasnformer. The status of oil health is generally assessed using these gas concentrations. Therefore, in the proposed model, 31 fuzzy rules are designed based on the severity levels of these gases in order to determine the health index (HI) of the oil. Similarly, any incipient faults along with their severity are also detected using the proposed fuzzy logic model with 22 expert rules. To validate the proposed fuzzy logic model, the data for dissolved gases in 50 working transformers operated by the Himachal Pradesh State Electricity Board (HPSEB), India, are collected. Over the years, calculations for the health index have been performed using conventional dissolved gas analysis (DGA) interpretation methods. The shortcomings of these methods, such as non-reliability and inaccuracy, are successfully overcome using the proposed model. The detection of incipient faults is normally performed using key gas, Rogers ratios, the Duval triangle, Dornenburg ratios, modified Rogers ratios and the IEC ratio codes methods. The shortcomings of these conventional ratio code methods in identifying incipient faults in some typical cases, ie multiple incipient fault cases, are overcome by the proposed fuzzy logic model.

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

scholarly journals Moisture content as an important integral parameter of transformer oil quality in power transformers of 10/0.4 kV substations

2019 ◽  
Vol 124 ◽  
pp. 05008
Author(s):  
V Trushkin ◽  
S Shlyupikov ◽  
G Eroshenko ◽  
M Levin ◽  
S Kifarak
Keyword(s):  
Moisture Content ◽  
Oil Quality ◽  
Transformer Oil ◽  
Power Transformers ◽  
Main Element ◽  
Integral Parameter ◽  
Information Analysis ◽  
Sample Test ◽  
Long Time ◽  
Transformer Insulation

The main element characterizing the transformer efficiency is the state of its isolation, and the first thing is operating oil, which can perform its functions for a long time with timely restoration of its properties. Transformer oil is the main dielectric being in contact with the external environment, interacting with solid insulation and carrying a large amount of diagnostic information. Analysis of the development of transformer insulation damage showed that the main catalyst for accelerating the aging process of the oil is the appearance of moisture in it. This effect is enhanced by oxygen, temperature, the catalytic action of metals, oxidation and other factors. To confirm the influence of moisture content in oil on the deterioration of its properties, a statistical analysis of the oil sample test protocols was carried out. The obtained data allowed us to determine the moisture content as an important integral parameter of oil quality. Recommendations are given on the inclusion of a moisture content parameter in a set of mandatory requirements, in particular, for 10/0.4 kV consumer transformer substations equipped with silica gel air dryers

Research of Ageing and Life Assessment Methods of Power Transformers in Nuclear Power Plants

2012 ◽  
Vol 614-615 ◽  
pp. 1109-1115 ◽  
Author(s):  
Cheng Feng Yang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Assessment Method ◽  
Thermal Ageing ◽  
Degree Of Polymerization ◽  
Transformer Oil ◽  
Life Assessment ◽  
Power Transformers ◽  
Analysis Method

The effective methods of the ageing and life assessment for large and medium-sized power transformers used in nuclear power plants are analyzed and described, including the thermal ageing life assessment method for transformer solid insulation, the gas analysis method of CO and CO2 in the transformer oil, the average degree of polymerization method, furfural content analysis method, and the analysis method based on the insulation ageing-related electrical parameters. The analysis results show that the methods used can reasonably assess the remaining life of the transformers. These methods have important reference value to the ageing and life management for the large and medium-sized power transformers in nuclear power plants.

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