Turbomachines

Turbomachines are rotary type machines where the transfer of energy is brought about by dynamic action. Here impervious boundary containing the fluid does not exist. In a  turbomachine, energy exchange is brought about by hydrodynamic forces that appear between a moving fluid and the rotating and stationary elements of the machine. Here a dynamic energy exchange is taking place between one or several rotating elements and a rapidly moving fluid. The main components of a turbomachine are a vane carrying rotating element which operates in a fluid stream, some stationary elements acting as guide vanes for the proper control of flow direction and the energy conversion process, two shafts and housing. A turbomachine creates thermodynamic and dynamic action between a slow moving surface and a static fluid. This action involves a change in either volume or displacement of the fluid. Some characteristics of turbomachine are high rotational speed, simple design, less weight and almost vibration free.

Overhead power lines

Two mechanisms exist for electric power transmission-underground cable transmission and overhead line transmission. Underground cable transmission is not commonly used because it is very expensive and it is very difficult there to provide proper insulation. The main components of overhead lines are conductors, line supports, insulators, cross arms, phase plates, danger plates, lightning arresters and anticlimbing wires. Conductor material should have high electrical conductivity, high tensile strength, highly economical and low specific gravity. Some commonly used conductor materials are copper, aluminium, steel cored aluminium (aluminium conductor steel reinforced), galvanized steel and cadmium copper. Line supports should have high mechanical strength, less weight, cheap, longer life span and accessibility. Commonly used line supports are wooden poles, steel poles, RCC poles and steel towers. Insulators are used to insulate line conductors from line supports. Commonly used insulators are pin type insulators, suspension type insulators, strain insulators and shackle insulators. These insulators should have high mechanical strength, high electrical resistance, high relative permittivity, non-porous and high ratio of puncture strength to flashover.