2006-09-15 11:00:52 · 4 answers · asked by G.K.Buchan 1 in Science & Mathematics ➔ Engineering
There are stepping transformers in the distribution circuit to step the voltage up and step the voltage down. Since power is equal to V*I, as the voltage is increased, the current decreases proportionally. Also, the line loss related to resistance is through the equation V=I*R, since power =V*I, power relates to current as: I^2R, where the voltage relates to power and resistance as V^2/r. In other words, high voltage is more efficient than high current in the transmission of electrical energy. Also, the current density of a wire is related to the heating of the wire. The thicker the wire, the more current it can carry without melting. The high voltage allows more energy to travel over smaller gage wires, thereby making the distribution system cheaper and more reliable.
Why the specific values? This would require an analysis of the distribution system to provide that answer.
2006-09-15 11:19:50 · answer #1 · answered by odu83 7 · 0⤊ 0⤋
The reason electricity is stepped-up to high voltage, during distribution, is to avoid Ohmic power loss.
Ohmic power loss is heat generated in an electric conductor based on the equation i^2*R. (That is, i-squared-times-R)
Where i is electric current and R is resistance.
When AC electricity is passed through a step-up Transformer the voltage increases and the current decreases. This is because power (energy per time) must remain constant and computed as i*v. (i-times-v, current times voltage).
The choice of the various voltages placed on transmission lines is based on the distance of the line. The longer the line, the greater R will be. So, for a longer distance run, a higher voltage is chosen.
2006-09-15 11:21:09 · answer #2 · answered by entropy 3 · 0⤊ 0⤋
It is to do with the turns-ratio of the transformers. If there are N1 turns on the primary and N2 turns on the secondary, then N1/N2 OR N2/N1 is typically an integer. I guess this is easier in the manufacturing process, and probably helps with managing harmonics and balancing ckts too. Thus voltages that are stepped up go up in integral amounts.
2006-09-15 12:25:19 · answer #3 · answered by noitall 5 · 1⤊ 1⤋
quantization
2006-09-15 11:17:09 · answer #4 · answered by danthemanbrunner 2 · 0⤊ 0⤋