The advantages of ester liquids for substation design

As the pressure on substation designers grows in terms of space limitations, cost, and safety, ester filled transformers can offer a useful solution to difficult problems at transmission as well as distribution voltages

Robert Southey's original Madoc : a transcript of the 1797-99 manuscript, with a detailed analysis of its development and sources

PhDWhen Robert Southey published his second epic, Madoc, in 1805, he had already been working on the poem in various stages for a decade. His first complete draft of the poem was composed between February 1797 and July 1799, and this version differs substantially from that which Southey was to publish six years later. In this thesis I have published, for the first time, what I call MS.2A in full, complete with all its deletions and emendations, transcribed from the original in the Keswick Museum in Cumbria. In my Appendix I have also provided detailed explanatory notes to each of the fifteen books. These not only elucidate textual references but trace many of Southey's ideas, descriptions, etc. to the numerous sources that he had consulted for the composition of MS.2A, several of which he was never to acknowledge in the notes to the published poem. My introductory chapter examines the critical problem which commentators have encountered (and in many ways exacerbated) by paradoxically recognising Madoc's accretive compositional process while refusing to engage with any of the earlier manuscripts. The chapters which follow recontextualise Southey's long-held interest in the Madoc legend, from his latter years at Westminster School to the publication of the poem in 1805, within the wider Southeyan biographical framework. Particular attention has been paid to that period when he was composing MS.2A - a period which he himself was to recollect as being the happiest and most productive of his life, and during which he produced many of his most enduring shorter poems. My penultimate chapter examines some of the political and religious issues arising out of MS.2A, while arguing that a true critical understanding of these issues can only be achieved by our willingness to engage with, rather than - as has traditionally been the case hitherto - merely dismissing Southey's selection (and even rejection) of source material. My final chapter explores in depth ten of Southey's major sources for the writing of MS.2A, and provides the reader with information relating to their origin and make-up, details concerning the editions which Southey might have used, and a feeling for their author's wider aims and ideological tenor. A number of minor sources are also discussed, so that this chapter paves the way for a fuller understanding of Southey's borrowings

The advantages of ester liquids for substation design

As the pressure on substation designers grows in terms of space limitations, cost, and safety, ester filled transformers can offer a useful solution to difficult problems at transmission as well as distribution voltages

The importance of thermal design to transformer lifetime

According to the evidence gathered from many large scrapped transformers over the years, some transformers seem to have aged thermally at much higher rates than others. This discrepancy cannot always be ascribed to the operating conditions, and it has become clear that some units have much higher internal temperatures and consequently more rapid ageing than expected. This column explores some of the potential reasons for this, some of the research that has been carried out and some of the considerations and techniques that can be applied to avoid problems in the future

Transformers and the energy system transition

Having spent most of my career in the engineering and asset management of transformers working for National Grid in the UK, I have recently taken the opportunity of moving into the academic world as a professor at the University of Manchester. National Grid gave me fantastic opportunities to work with transformer manufacturers and see many transformer factories around the world. As well as having to understand how transformers fit into the wider transmission system and substations in particular, I had to play my part in ensuring they were reliable, safe and economic over their lifetimes. Through IEC (I had the great privilege of being chair of IEC TC14 2008-2017) and CIGRE, I was lucky enough to be able to work with colleagues from other utilities, academics and suppliers, to help the industry with standards and research, something I hope to continue doing as well as taking the opportunity to develop a broader view

The importance of thermal design to transformer lifetime

According to the evidence gathered from many large scrapped transformers over the years, some transformers seem to have aged thermally at much higher rates than others. This discrepancy cannot always be ascribed to the operating conditions, and it has become clear that some units have much higher internal temperatures and consequently more rapid ageing than expected. This column explores some of the potential reasons for this, some of the research that has been carried out and some of the considerations and techniques that can be applied to avoid problems in the future

A new approach to understanding the frequency response of mineral oil

Dielectric spectroscopy is non-invasive diagnostic method and can give information about dipole relaxation, electrical conduction and structure of molecules. Since the creation of charge carriers in mineral oil is not only from dissociation but also injection from electrodes, the injection current cannot be simply ignored. The polarization caused by the charge injection has been studied in this paper. Based on our research, if the mobility of the injected charge carriers is fast enough so that they can reach the opposite electrode, the current caused by the injection will contribute only to the imaginary part of the complex permittivity and this part of the complex permittivity will decrease with the frequency with a slope of -1 which is in a good agreement with the experimental result. The classic ionic drift and diffusion model and this injection model will be combined to make an improved model. In this paper, the frequency responses of three different kinds of mineral oils have been measured, and this modified model has been used to simulate the experiment result. Since there is only one unknown parameter in this improved model, a better understanding of the frequency response in mineral oil can be achieve

Space charge dynamics in oil combined with pressboard insulation system under AC and DC superimposed electric field

Space charge has been a general concern related to the reliability and the lifetime of HVDC components. Recently, the researches on space charge characteristics and its impacts in solid insulating materials have attracted many attentions and been widely reported under DC electric fields. It has been found that the enhanced electric field due to space charge can accelerate ageing and lead to a permanent failure eventually. However, the insulation may withstand more complex stresses in converter transformers i.e. both AC voltage and DC voltage are applied on the second winding of converter formers. The space charge dynamics under this superimposed electric field is not well understood. In the presence paper, the space charge dynamics in the pressboard impregnated with different ageing statuses oil under pure AC voltage (50 Hz), pure DC voltage and AC/DC superimposed voltage have been investigated using the pulsed electroacoustic (PEA) technique with a fast data acquisition system. Space charge profiles were measured in insulation system consisted of either single layer oil impregnated pressboard or oil/oil impregnated pressboard. Two types of mineral oil (the fresh and the service aged) were used in this work. The results show that the amount of space charge under pure AC voltage is generally very small compared with DC voltage. However, when a small DC offset is superimposed with AC stress, homo charge injection (corresponding to the polarity of the DC offset) can be clearly observed. The charge amount and charge movement are evidently increased under the superimposed stress, particularly, in the fresh oil/pressboard insulation system. It has been found that the charge amount is generally larger under the superimposed stress than the sum of the pure AC and DC space charges, due to the non-linear space charge injection of the applied field. The impact of the superimposed AC/DC stress needs to be considered when designing, testing and operating converter transformers

Mono and dinuclear ruthenium complexes as anti-cancer therapeutic leads

This thesis details chemistry and cell biology based interdisciplinary studies on a series of ruthenium based biomolecular probes that were synthesised and investigated for their anti-cancer properties. The previously reported mononuclear ruthenium-based [(phen)2Ru(tpphz)]2+ and three related new complexes were synthesised as a series to explore DNA binding. Binding to genomic DNA in vitro was confirmed for all complexes utilising their luminescence properties – specifically the DNA light switch effect via aqueous luminescence titrations. Cellular activity in the model of cisplatin sensitive/resistant A2780/A2780cis human ovarian carcinoma was then studied, with IC50 concentrations determined for each complex in each cell line and adequately repeated. This revealed a clear series of toxicities comparable to the level of cisplatin, furthermore a variety of positive and negative cross resistance profiles were observed. Time lapse microscopy data was then obtained for each complex and cell line permutation to visualize the mode of cell death, and a proteomic study was conducted with the aim of gathering more mechanistic detail behind the cell death pathway. After optimisation of a consistent workable protocol, photocytotoxicty was also investigated. Although this work was primarily with the ruthenium-rhenium and ruthenium-platinum binuclear complexes of the original series, further systems incorporating ruthenium-rhenium molecules were also investigated. Interestingly, these studies revealed contrasting phototoxic activity and a particularly impressive phototoxic index score for a Ru2Re2 macrocyclic cation