Power transmission
Power transmission is moving energy from where it is made to where it is used.
Power is defined formally as units of energy per unit time. In SI units: 1 watt = 1 joule/s = 1 newton * metre/second (1W=1J/s=1N·m/s).
Electrical power
With widespread establishment of power grids, power transmission has came to be associated most often with electric power transmission.
Mechanical power
Electrical power transmission has replaced mechanical power transmission in all but the very shortest distances. From the start of the industrial revolution until the end of the 19th century mechanical power transmission was the norm. Factories were fitted with overhead driveshafts providing rotary power. Drivebelts would provide power to individual machines on the shop floor.
Mechanical power may be transmitted directly using a solid structure such as a driveshaft; transmission gears can adjust the amount of torque or force vs. speed in much the same way an electrical transformer adjusts voltage vs current.
Chemicals and fuels
Chemical energy is transmitted by moving fuels to generate power in distant places. Pipelines and other large infrastructure projects transport natural gas, petroleum and petroleum products for use as fuel.
Power Transmission Media
Electric power transmission with overhead line.
Electric power transmission with underground cable. Here (1) is the conductor for heavy currents and (3) the insulation for high voltages.
Mechanical power transmission
