Investigating The Impacts Of Ageing And Moisture On Dielectric Response Of Oil/Paper Insulation Systems

The oil/paper insulation system in a transformer degrades under various chemical, thermal and electromechanical stresses during its operation. Dielectric response measurements like the Return Voltage Measurement (RVM) and Polarisation and Depolarisation Current (PDC) measurement are currently being used for condition assessment of the insulation. In the current research project, the ageing condition and the moisture content of both paper and oil samples have been varied over a controlled range and their effects on the dielectric response measurements have been investigated. Experimental results are provided in this paper to demonstrate the effects of both ageing and moisture content of paper and oil on the RVM and PDC results

Some Precautions for the Field Users of PDC Measurement for Transformer Insulation Condition Assessment

The need for economic, reliable and effective delivery of electric power has lead to the search for new, efficient and effective methods for diagnosing the insulation of the HV equipments in the industries all over the world. One of the methods currently being investigated as a potential nondestructive diagnostic tool for condition monitoring of the oilpaper insulation of power transformers is the Polarisation and Depolarisation Current (PDC) measurement. This paper starts with a theoretical and physical description of the PDC technique. Several practical aspects of the technique have been discussed in the paper along with corresponding experimental and field test results. These physical considerations can be used as 'precautions' for the potential field users of the PDC technique for insulation condition assessment of transformers

Investigation of an Expert System for Condition Assessment of Transformer Insulation Based on Dielectric Response Measurements

The need for economic, reliable, and effective delivery of electric power has led to the search for fast, efficient, and effective methods for diagnosing the insulation of high-voltage (HV) equipment in the power industries. The recent dielectric techniques that have been carefully considered by major industries for transformer insulation condition assessment are the recovery voltage method (RVM) and the polarization and depolarization current(PDC) measurement. However, due to the complexity of the transformer insulation structure and various degradation mechanisms under multiple stresses, insulation condition assessment is usually performed by experts with special knowledge and experience. In this paper, an expert system (ES) is developed, which imitates the performance of a human expert, to make the complicated insulation condition assessment procedure accessible to plant maintenance engineers. The structure of the ES is described in detail including knowledge base, inference engine, and human-computer interface. Examples of the application of the ES are also presented to confirm that the system can provide accurate insulation diagnosis

Condition Monitoring Of Transformer Insulation By Polarisation And Depolarisation Current Measurements

The measurement and evaluation of the 'dielectric response' is one possible way of diagnosing a transformer's insulation condition. Moisture and ageing strongly influence the dielectric properties of oil/cellulose insulation systems. In our recent research project, dielectric measurement was used for assessing the condition of oil/paper insulation. The Polarisation and Depolarisation Current (PDC) analysis is a non-destructive dielectric testing method for determining the conductivity and moisture content of insulation materials in a transformer. On the basis of this analysis one can decide upon further actions. This paper presents a description of the PDC technique with the physical and mathematical background and some results of dielectric response measurements of several transformers. Data analysis and interpretation of the field test results are also presented in this paper

Experience With Dielectric Response Measurements On Oil-Paper Insulated Cables

Deterioration of the underground power cables insulation has been established to be caused by electrical, thermal and environmental stresses. With the degradation of dielectric strength of the insulation, the underground cables will not be able to function optimally or as planned. As a supplement to the existing dissipation factor and other conventional cable diagnostic measurements, the Decay Voltage (DV) and the Return Voltage (RV) measurement technologies are currently being proposed for nondestructive diagnosis of cable insulation. The main purpose of this paper is to present results from laboratory measurements of DV, RV and Polarisation and Depolarisation Current (PDC) on a number of samples of oil-impregnated paper insulated cables. Comparison of these results has also been made with the conventional dissipation factor measurement data for the same cables

Investigating Some Important Parameters of the PDC Measurement Technique for the Insulation Condition Assessment of Power Transformer

The need for economic, reliabe and effective delivery of electric power has led to the search for new, efficient and effective methods for diagnosing the insulation of the HV equipments in the industries all over the world. One of the methods currently being investigated as a potential non-destructive diagnostic tool for condition monitoring of the oil-paper insulation of power transformers is the Polarisation and Depolarisation Current (PDC) measuremnet. This paper starts with a theoretical and physical description of the PDC technique. Several practical aspects of the technique have been discussed in the paper along with corresponding experimental and field results

Impact of the condition of oil on the polarisation based diagnostics for assessing the condition of transformers insulation

The oil/paper insulation system in a transformer degrades under various chemical, thermal and electromechanical stresses. Among the newer dielectric response measurements, Polarisation and Depolarisation Current (PDC) measurement has the strength to monitor the quality of oil and papers conditions separately on the overall diagnostic results. In the current research project, the ageing condition and the moisture content of both paper and oil samples have been varied over a controlled range and their effects on the dielectric response measurements have been investigated. Particular emphasis has been given to use different oil samples from field transformers. Experimental results are described in this paper to demonstrate the effects of both ageing and moisture content of oil on PDC results. A mathematical tool has also been used to model the equivalent circuit of polarisation process to monitor the impact of oil on diagnostics

Evaluation of buprofezin 70 DF an insect growth regulator for eco-friendly management of jassid (Amrasca bigutulla bigutulla Ishida) in okra, Abelmoschus esculentus (L.) Moench

Field experiments were carried out for two seasons in 2012 to evaluate the efficacy of a new formulation of buprofezin (buprofezin 70 DF) against jassid (Amarasca biguttula biguttula Ishida) in okra, Abelmoschus esculentus (L.) Moench. The insecticide was applied at 200 and 150 g a.i./ha at the ETL level of the insect (2 Jassids/leaf) and the performance of the same was compared with imidacloprid 17.8 SL @ 20 g a.i./ha, acephate 75 SP @ 562.5g a.i./ha and an untreated control. Results revealed that both the dosages of buprofezin 70 DF were significantly superior over the untreated control at 5 % level of significance. Buprofezin 70 DF at 200 and 150 g a.i./ha performed better over the other treatments with 88.81 and 85.96 % reduction during first season and 89.60 and 84.73% reduction during second season, respectively. Buprofezin , an insect growth regulator which had less or no hazardous effects on human health and environment and thus it can be incorporated in Integrated Pest Management programme in okra cultivation

Identification of miR-379/miR-656 (C14MC) cluster downregulation and associated epigenetic and transcription regulatory mechanism in oligodendrogliomas

Introduction Although role of individual microRNAs (miRNAs) in the pathogenesis of gliomas has been well studied, their role as a clustered remains unexplored in gliomas. Methods In this study, we performed the expression analysis of miR-379/miR-656 miRNA-cluster (C14MC) in oligodendrogliomas (ODGs) and also investigated the mechanism underlying modulation of this cluster. Results We identified significant downregulation of majority of the miRNAs from this cluster in ODGs. Further data from The Cancer Genome Atlas (TCGA) also confirmed the global downregulation of C14MC. Furthermore, we observed that its regulation is maintained by transcription factor MEF2. In addition, epigenetic machinery involving DNA and histone-methylation are also involved in its regulation, which is acting independently or in synergy. The post- transcriptionally regulatory network of this cluster showed enrichment of key cancer-related biological processes such as cell adhesion and migration. Also, there was enrichment of several cancer related pathways viz PIK3 signaling pathway and glioma pathways. Survival analysis demonstrated association of C14MC (miR-487b and miR-409-3p) with poor progression free survival in ODGs. Conclusion Our work demonstrates tumor-suppressive role of C14MC and its role in pathogenesis of ODGs and therefore could be relevant for the development of new therapeutic strategies

Degradation dynamics and dissipation kinetics of an imidazole fungicide (Prochloraz) in aqueous medium of varying pH

Laboratory degradation studies were performed in water at pH 4.0, 7.0 and 9.2 using Prochloraz (450 EC) formulation at the concentration of 1.0 (T1) and 2.0 (T2) µg/mL. Water samples collected on 0 (2 h), 3, 7, 15, 30, 45, 60 and 90 days after treatments were processed for residue analysis of Prochloraz by HPLC-UV detector. In 60 days, dissipation was 89.1–90.5% at pH 4.0, 84.1–88.2% at pH 7.0, and 92.4–93.8% at pH 9.2 in both treatments. The results indicate that at pH 7.0 the degradation of Prochloraz was much slower as compared to other two. Between pH 4.0 and 9.2 the degradation of compound is little faster at pH 9.2. The half-life periods observed were 18.35 and 19.17 days at pH 4.0, 22.6 and 25.1 days at pH 7.0 and 15.8 and 16.6 days at pH 9.2 at T1 and T2 doses respectively