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Alghamdi A.S.,University of Technology Malaysia | Alghamdi A.S.,Technical and Vocational Training Corporation | Muhamad N.A.,University of Technology Malaysia | Suleiman A.A.,University of Technology Malaysia | Suleiman A.A.,Nigerian National Agency for Science and Engineering Infrastructure
Transactions on Electrical and Electronic Materials

DGA is one of the most recent techniques developed to diagnose the fault condition on oil filled insulation transformers. There are more than 6 known different methods of DGA fault interpretation technique and so there is the likelihood that they may vary in their interpretations. A series of combined interpretation methods that can determine the power transformer condition faults in one assessment is therefore needed. This paper presents a computer program-based system developed to combine four DGA assessment techniques; Rogers Ratio Method, IEC Basic Ratio Method, Duval Triangle method and Key Gas Method. An easy to use Graphic User Interface was designed to give a visual display of the four techniques. The result shows that this assessment method can increase the accuracy of DGA methods by up to 20% and the no prediction result had been reduced down to 0%. © 2012 KIEEME. Source

Olasupo O.A.,Nigerian National Agency for Science and Engineering Infrastructure | Borode J.O.,Federal University of Technology Akurre
Refractories and Industrial Ceramics

The effect of sintering temperature on the properties of aluminosilicate ramming mass was investigated. Two refractory compositions, namely clay - silica - mica - bentonite (80 - 10 - 20 - 4) and clay - silica - mica - Durax (80 - 10 - 20 - 4), were investigated. Each of these compositions was thoroughly mixed in a laboratory sand mixer using 5% tempering water. Moulded samples of ∅50 mm x 50 mm height were then prepared from them using the AFS standard ramming machine. The samples were dried at 120°C for 110 min. These samples were fired at different temperatures of 1000, 1100, 1200, 1300, 1400, and 1500°C. The fired samples were thereafter tested for such properties as apparent porosity, cold compression strength, linear shrinkage, volumetric firing shrinkage, thermal shock resistance, and refractoriness at these temperatures. The results obtained indicated that the rise in cold compression strength for all samples with increasing temperature reaches a maximum before failure at the refractoriness point of 1500°C. The apparent porosity and volumetric shrinkage decrease with increasing temperature. At all temperature ranges, the materials exhibit excellent thermal shock resistance. These compositions are therefore recommended for lining of rotary furnaces for melting of cast iron. © 2012 Springer Science+Business Media, Inc. Source

Bolarinwa M.A.,University of Ibadan | Adetunji A.R.,Prototype Engineering Development Institute | Adewoye O.O.,Nigerian National Agency for Science and Engineering Infrastructure
Advanced Materials Research

The Scanning Electron Microscope (SEM) has been used to study the adhesion of red oxide primer on selected substrates. The substrates are stainless steel, mild steel, galvanized steel and aluminium. Twenty (20 No) specimens were prepared from the four different substrate metals and examined metallographically, after coating them with red oxide primer using different methods of application. Results showed varying degrees of adherence. The red oxide primer was able to form bonds with the different substrate metals, especially with the well cleaned, primed and subsequently painted stainless steel specimen. © (2012) Trans Tech Publications, Switzerland. Source

Suleiman A.A.,Nigerian National Agency for Science and Engineering Infrastructure | Suleiman A.A.,University of Technology Malaysia | Muhamad N.A.,University of Technology Malaysia
International Review on Modelling and Simulations

The dielectric properties of insulation oil in power transformers are dependent on the chemical structure of the oil. Although mineral oil based insulation oil is the common liquid dielectric used in power transformers, environmental and safety issues are pressurizing many stakeholders from developed countries to consider alternative fluid as transformer fluids. Vegetable (natural ester) based insulation oil is a viable alternative that has been commercialized in some countries. This paper presents results from the study done to ascertain the feasibility of using commercially available biodegradable insulation oil (Envirotemp® FR3™) for Malaysia power transformers. It was found that the tested oil failed to meet some of the standard insulating property values as stipulated in the Malaysian Standard (MS 2322:2010) and this was because the MS 2322:2010 is the standard for "Fluid for electrotechnical application-Unused mineral insulating oils for transformers and switchgear" which cannot be applied to Vegetable based insulation oil. This can lead to a misleading conclusion on the characteristics of natural ester oil as a substitute to mineral oil in power transformers. It is therefore pertinent to have a Malaysian standard property values for vegetable oil (natural esters) guiding researcher, manufacturer and users of "vegetable oil (natural ester) filled transformer in Malaysia". © 2011 Praise Worthy Prize S.r.l. - All rights reserved. Source

Ibrahim O.,University Of Ilorin | Amuda S.A.Y.,University Of Ilorin | Mohammed O.O.,University Of Ilorin | Kareem G.A.,Nigerian National Agency for Science and Engineering Infrastructure
International Journal of Electrical and Computer Engineering

Accurate tuning of controller in industrial process operation is prerequisite to system smooth operation which directly reduce process variability, improved efficiency, reduced energy costs, and increased production rates. Performance evaluation of a model based PID controller tuning algorithm on a chemical process plant is presented in this paper. The control action of three different PID controller tuning algorithms namely; Hagglund-Astrom, Cohen and Coon, and Ziegler-Nichols on the process plant was examined in a closed loop control configuration under normal operating condition and in the face of disturbance. LabVIEW software was used to model a chemical process plant from open loop control test data. The time domain response analysis of the controllers shows that each tuning algorithm exhibit different time response. Ziegler-Nichols algorithm shows the best performance with fastest rise time, settling time and was able to restore the system back to normal operating condition in a short time when subjected to disturbance compare to Cohen & Coon controller and Hagglund-Astrom algorithm settings. © 2015 Institute of Advanced Engineering and Science. All rights reserved. Source

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