I don't understand the benefit, especially in electrical transmission. Furthermore I don't know why AC is better for transmission other than the fact historically speaking, converting DC back to AC was impossible- but as far as I know DC current is better because it uses the entire cross-section of the conductor as opposed to the skin effect that AC causes, so in this day in age isn't DC smarter? For example the huge HVDC line that services parts of California. Or does AC travel further distances? Why is it that AC can be stepped up or down with transformers, but DC can't?I don't know what a rotating magnetic field is why this is good for electric motors, and I don't know why it is helpful for their peak voltages to all be offset.
When you step up the voltage in long distance transmission, you reduce the current for the same power. So you can transmit more power with the same size wire. And in distribution it is necessary to drop the voltage so AC is the way to go. AC can be transformed because the fluctuation of the voltage allows for transforming. In the transformer a magnetic field is induced into the core and then this field is tapped by a different number of coils in order to increase or decrease the voltage. Since DC does not reverse itself, the magnetic field stays constant and there is no fluctuation of the field. Current is induced in a conductor by the conductor moving within a magnetic field or the field moving with respect to the conductor. This does not happen with DC.
Historically, the first power systems were DC only. Voltages could be stepped up (and currents stepped down) using dc motor-generator sets. The invention of AC power let to a much less costly way of changing voltage and current: by using transformers. The California HDVC intertie has the distict advantage of not tying two separate grid systems together synchronously. If one part of a grid starts to fail and triggers a cascading effect that takes down the entire grid, it won't continue through the intertie to effect the other grid.
AC voltage. For transmission purposes is stepped up to around 50,000 volts so if you lose 50-80 volts it is a very small percentage of the total. If you tried to send it long distances at 100 volts and lost 50 to 80 volts your voltage would be to low to be usable at the other end. DC has a steady single voltage AC voltage varies from (in 120 V) +60 volts to -60 volts. It is this variation in voltage that is required to make a transformer function. DC cannot be used in a transformer. You are stuck with a single voltage, thus as stated in the first paragraph DC voltage is difficult to use over long distances like 20 miles or more. A rotating magnetic field is essential for electric motor operation. With three phase current there are three different sections to each magnetic pole and they reach their peaks at different times. This offset creates a magnetic field that is constantly rotating around the motor. The rotating magnetic field creates an electromagnet in the rotating assembly. Because opposite poles attract and like poles repel, the rotating assembly (rotor) is pushed and pulled to keep up with the rotating field that is in the wiring of the stationary part of the motor (stator). I hope I haven't confused you a lot, I've tried to address most of your questions.
1) Let There Be Rock 2) High Voltage 3) Highway to Hell As you can see I prefer Bon Scott on vocals. Here's my top 3 with Brian Johnson: 1) Back in Black 2) The Razor's Edge 3) Ballbreaker
