Applications of new technology in power substations
The authors describe the applications of some of the more modern technologies to instrument designed specifically to operate in utility substation environments. Particular emphasis is placed on the use of CMOS logic, processor, and memory circuits, high-density flexible magnetic disk media, and high-capacity Winchester technology storage devices. The operating history of a number of units over a five-year period is reported, as well as the steps taken to protect these devices in a hostile environment. In addition, areas requiring specific improvement and adaptation are noted.<<ETX>>
Measurement of switching transients in 115 kV substation
Bus current transients, electric and magnetic field transients, and current transients coupled onto control and CT cables produced by switching operations in a 115 kV ring bus have been measured and characterized. The similarities and differences among transients observed when energizing and deenergizing relatively short sections of bus during disconnect switch and circuit breaker opening and closing operations are summarized and discussed. The results are used to further the understanding of switching transient characteristics and to validate a model that predicts the detailed nature of the transients reported, for use in ongoing investigations to assure continued satisfactory performance in substation protection equipment. >
A comparative performance assessment of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
Abstract This work presents the investigation results of a journal bearing lubricated with magnetorheological fluid that is activated by a local constant magnetic field to vary both the local flow resistance and pressure. The bearing performance is assessed via Finite Element Modelling (FEM) and results are corroborated by experiments. The FEM model uses the Bingham model to describe the fluid film. A dedicated test rig is used to assess the hydrodynamic behavior of the bearing with magnetorheological fluid, and the results are compared with the same geometrical bearing lubricated with oil. Thicker fluid films at low speeds, beneficial pressure distribution, and higher friction losses under all operating conditions are observed in the bearing with magnetorheological fluid compared to the oil lubrication.