摘要:

Infrared absorption measurements allow the concentrations of specific liquids and gases to be measured. When infrared light-emitting-diode (LED) sources are employed, the infrared monitor can be made compact, low-powered and stable, and therefore suitable for portable applications. The characteristics and advantages of LED technology are discussed, and examples are given of commercial instruments developed to measure moisture in oil and carbon dioxide in air.

ISSN:1479-8344    

DOI:10.1049/pe:19920014

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The past decade has seen great progress in our understanding of the mechanisms involved in the electrical breakdown of insulating liquids. This ‘academic’ approach has mostly used pure liquids in small quantities, and often the point-plane electrode configuration has been employed in the process of elucidation. To ‘practical engineers’ guided by standards and specifications set by the IEC (e.g. IEC 156) or other bodies little has changed over the past decade or two. Standard tests still give a standard deviation of the order of 20%, and water ingress, particle and fibre contamination and gas in solution are still the prime concern. How are these two view points to be reconciled?

ISSN:1479-8344    

DOI:10.1049/pe:19920015

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Issues of energy utilisation are now of international importance. The predictions of global temperature increases due to the combustion of fossil fuels have been well publicised, and conservation of the environment is becoming a significant political issue. 20% of the world's people account for 80% of the world's energy use, and this will clearly not remain the case for ever. The potential appetite of humanity for energy is enormous and, when compounded with rapid population growth, this will give rise to tremendous challenges and opportunities for politicians, and engineers, of all nations over the next decades. We must find ways of optimising our energy needs if our Western lifestyle is to continue. It has also been well publicised that buildings account for nearly half of the UK total energy use, and it is therefore imperative that we adopt the best energy technologies in both new and refurbished buildings.

ISSN:1479-8344    

DOI:10.1049/pe:19920016

出版商:IEE    

年代:1992

数据来源: IET

摘要:

There is one common factor that, in different forms, runs throughout the entire electrical and electronics industries. That factor is the requirement for insulation that gives the necessary mechanical, thermal and electrical properties needed for particular applications. At low voltages, the overriding requirement is normally to satisfy the mechanical limitations of application or manufacture; at higher voltages, the electrical performance of the insulation becomes more critical and will be a determining factor in the complete equipment specification.

ISSN:1479-8344    

DOI:10.1049/pe:19920017

出版商:IEE    

年代:1992

数据来源: IET

摘要:

For several years manufacturers and users of electrical and electronic equipment have become aware of the significance of electromagnetic compatibility (EMC). The complexity of modern equipment of all types, the widespread introduction of electronic devices with low threshold logic levels, the proliferation of radio transmitters and mobile systems of all types and modern power-handling switching techniques have all created an environment in which EMC is becoming a paramount factor in design

ISSN:1479-8344    

DOI:10.1049/pe:19920018

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Operators of power generation and combined heat and power plant need to make decisions on a regular basis. Some of these decisions relate to safety, engineering and contractual matters, where there is often no room for manoeuvre; the rest could be considered as degrees of freedom in the sense that there is choice in the way that the overall objectives are met. It would be misleading, however, to conclude that the latter choices are in any sense arbitrary, they often have an impact on the overall economics of the plant. This article will: (i) explain how the above constitutes a modelling and optimisation problem which can be solved in a number of ways using currently available, proven hardware and software; (ii) give examples of applications in CHP/power-generation plants; and (iii) indicate the scale of the potential benefits, in terms of reduction in energy usage.

ISSN:1479-8344    

DOI:10.1049/pe:19920019

出版商:IEE    

年代:1992

数据来源: IET