Evaluation of strand-to-strand capacitance and dissipation factor in thermally aged enamelled coils for low-voltage electrical machines

© The Institution of Engineering and Technology 2019. The dissipation factor (i.e. tanδ) and insulation capacitance (IC) measurements are conventional monitoring methods for assessing the aging level of insulation systems. These quantities provide an invaluable indication of the dielectric losses within the insulating materials. However, how these values are affected by the aging processes due to thermal stresses have until today never been investigated fully. Thus, this study exhibits the influence of thermal aging on tanδ and IC of windings for electrical machines (EMs). The work is performed for class 200, round enamelled magnet wire specimens. The study aims at improving the design process of EMs for short duty cycle applications; hence, its outcome might be included at the design stage for enhancing reliability and lifetime. Random wound coils are chosen in the performed study, because they are the most common winding arrangement for low-voltage EMs, which are employed in a wide range of applications (e.g. from home appliances to aerospace motors). Based on the collected data, considerations regarding the impact of relative humidity on both the dissipation factor and IC are presented. Finally, the correlation between the partial discharge inception voltage and the diagnostic measurements is experimentally verified

(pol.p, p') Reactions on Heavy Transitional Nuclei

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Clinical xenotransplantation [10] (multiple letters)

10.1016/S0140-6736(03)14660-0Lancet36293931421-1422LANC

Polarized Proton Scattering from 88-Sr: Determination of Neutron Transition Densities

This research was sponsored by the National Science Foundation Grant NSF PHy 87-1440

Empowering innovative improvements through creative construction procurement

The heightened state of flux in the construction industry in general and construction procurement strategies in particular, provides welcome opportunities to inject innovative improvements. While some improvements are generated from within the construction industry itself, these evolve sluggishly along prolonged learning curves. These are compared with lessons to be learnt and examples to be drawn from manufacturing in the development of a marketable product. A product development focus is thus advocated in re-integrating segregated groups and in empowering and inspiring the innovations that are needed to achieve the dramatic productivity gains now demanded from the construction industry. © 2001, MCB UP Limite