摘要:

The production of torque in a hysteresis coupling is described by reference to the flow of energy in its air-gap and arbor regions and applying Poynting's theorem to deduce the power crossing into the rotor annulus. The formulation of appropriate Poynting surface and vectors is given and the theory is applied to a 2-pole experimental coupling. The computed torque is shown to compare well with the measured values. The analysis brings out the significance of pole tips of the field system in controlling the development of torque. It is shown that the harmonics of the space MMF contribute appreciably to the total developed torque.

DOI:10.1049/ip-a-1.1983.0054

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Earlier theoretical studies consider current dominant coupling only as being responsible for crosstalk between two coaxial cables and ignore coupling due to electric field parameters. In the paper, general crosstalk equations between two similar braided coaxial cables are derived by including both electric and magnetic coupling parameters in the analysis. The numerical studies based on the derived coupling models are applied to various braid constructions and load configurations are imposed on the tertiary circuit to assess the relative importance of each coupling parameter. From these studies, it is shown that the theoretical treatments which are based on the current dominant coupling give an incomplete assessment of the physical process and, even with a short-circuited tertiary, electric coupling parameters may play an important role in determining the coupling pattern for certain braid constructions.

DOI:10.1049/ip-a-1.1983.0055

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Methods of magnetising steel strip in continuous production lines have been developed so that magnetisation can be accomplished without enwrapping strip with conductors. Magnetisation can be achieved both in line with the strip rolling direction and across the strip width at 90° to the rolling direction. Appropriate sensing systems have been developed so that magnetic parameters such as loss and permeability can be measured at 0° and 90° to the rolling direction, without enwrapping the strip with sensing conductors.

DOI:10.1049/ip-a-1.1983.0056

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The electrostatics analysis package PE2D has been used to investigate the electric potential distribution in cylindrical transmission lines under conditions of progressive displacement of the inner conductor from the ‘coaxial’ case. The implications for the high voltage insulation characteristics of such deformed lines is discussed.

DOI:10.1049/ip-a-1.1983.0057

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The errors of a 2-stage current transformer (CT) are analysed when used as an isolated device or when used in a differential circuit. It is shown that when the CT is used in a differential circuit, or is operated at near zero external burden, a reduction in the errors of around two orders of magnitude can be gained. It is also shown that where the errors of a CT are largely a result of dielectric leakage, or of partial magnetic coupling, 2-staging will do little or nothing to reduce the errors.

DOI:10.1049/ip-a-1.1983.0058

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Microdischarge behaviours in a gap between the plane electrode and a charged conducting spherical particle moving in the presence of external electric field have been investigated. The microgap studied has distinctive features: (a) the field strength in the microgap changes very rapidly with the motion of the sphere even if the applied external electric field is static, (b) the boundary of the microgap changes with time and (c) the potential difference across the microgap is influenced from the occurrence of discharge due to the neutralisation of charge on the sphere by the charge carrier in the discharge itself. The random appearance of an initiating electron required for the development of an avalanche and the rapid changes of electric field, gap boundary and potential difference result in the statistical behaviours of microdischarge. The statistical characteristics at the microdischarge threshold and on the microdischarge length have been measured, and the microdischarge mechanism has been discussed to explain the characteristics.

DOI:10.1049/ip-a-1.1983.0059

出版商:IEE    

年代:1983

数据来源: IET

摘要:

Linear prediction parameters have been used to study the vocal changes accompanying a case of laryngitis, the aim being to quantify the vocal degeneration so as to monitor the progress of the laryngeal disfunction. The effectiveness for this purpose of a number of parameters (predictor coefficients, autocorrelation function, area coefficients, long-area ratios, PARCOR coefficients and cepstrum) and metrics (the Euclidean and Itakura distances and the crosscorrelation function) are compared and discussed'in the paper. Of the parameters used the most intrinsically sensitive (as measured by the Kullback divergence) are the PARCOR coefficients. However, when a metric is introduced to measure the deviation from normal vocal performance, the combinations producing the best results seem to be the Itakura distance applied to the predictor and autocorrelation coefficients and the crosscorrelation of the cepstral coefficients, both of which appear capable of registering changes in the patient's vocal condition which might pass unnoticed in a conventional noninvasive examination. The way seems to be open towards effective quantification of voice deformation for the diagnosis and treatment of laryngeal disorders.

DOI:10.1049/ip-a-1.1983.0060

出版商:IEE    

年代:1983

数据来源: IET

摘要:

The potential for sea-wave-energy exploitation is high in waters around the UK. Generating stations would typically be 2000 MW in rating, about 30 km long and be situated 10—15 km offshore, the energy being transmitted as electricity in submarine power cables. For such developments to be economic, a high degree of plant availability is necessary so that the maximum amount of energy can be converted and transmitted ashore. This requirement for high availability leads to the need for carefully designed protection and monitoring equipment. In addition, because the plant will be unmanned and because maintenance can be carried out only during short periods of the year, control, operating and monitoring philosophies must be developed, which may be quite different to those normally applied on land-based systems. In the paper, an approach is described which bases control, operating and maintenance around comprehensive condition monitoring of generating plant. Details are given of how information from such instrumentation can be used not only for health monitoring of plant, but also as an aid to operation and to scheduling and design of maintenance procedures.

DOI:10.1049/ip-a-1.1983.0061

出版商:IEE    

年代:1983

数据来源: IET