# How AC Power is generated?

In this tutorial, we are going to learn about How AC Power is generated?

Most of our electrical energy comes from magnetic fields contained within turning generators. The creation of energy is generated from the stationary magnetic fields of magnetic flux in field poles which are then included into electrical current by a turning generator rotor.  The centre of the magnetic field is stronger than the field that exits around the edges. As the generator is turned within these fields, it creates different levels of induced voltage force throughout its rotation. The output of the generator creates an alternating wave of voltage and current as shown above current leaves the generator from the rotor’s brush rigging.

The effective average voltage of the wave is the voltage rating of the generator. It is about 71% of the heights wave magnitude.  Each half –cycle, the wave change in polarity. The voltage continues to produce electrical force both in positive and negative polarities.  In the first half cycle, current flow the generator, the second half cycle results in hole flow from its output. In two phase system the difference in phase of each output line.

Every generator has a maximum output level. It is primarily based on the size of the magnetic field produced inside the stator of the generator. The rotor turns through the stationary field of the field winding to convert the magnetic flux into electrical current.  The current output has an opposite polarity from the magnetic field of the stator. The larger the output current, the more energy is required by the prime movers of the generator to turn the rotor. Conservation of energy laws state that the power out cannot exceed the power into the generator. The more output a generator has, the more energy which is required to physically turn the rotor through an increasingly stronger magnetic field of the stator.

The position of the output wave in time is called its phase.  Some generators put out more than one wave of energy. In common generator, output is generally single phase – two waves at 180o degrees apart or three- phase each wave 120 degrees apart. The advantage of a multi phase generator is a higher voltage and more current for high power use device and high power distribution system.  A typical home receives power as 2-phase power; many industrial sites use three phase system.

In two phase electrical system, two hot wires are supplied with a third Neutral/Grounding wire. The voltage across the two hot wires is twice the voltage of a single hot wire, the phase is 180 degrees apart, it is commonly today to share a neutral between two out of phase hot wires. This can save money by eliminating one wire in an electrical system.

To get DC voltage and currents from an AC distribution centre, a conversion process is done. Converting the AC source to DC is accomplished by using a DC power supply. Power supplies are located inside industrial equipment and has an AC power input with a DC output.  DC voltages are ideal for controlling modern computer controlled machine.

AC Circuit – Sharing of currents between devices.

AC circuits consist of Resistive, Capacitive, and Inductive device.  Example of resistive device is Lamps, Resistors, or Heating elements. Capacitive devices are capacitors, with inductive devices consisting of inductors, transformers, and solenoids. Analysis of AC circuits can be complex, it can require high level math to analyze energy usage. Each type of device uses power at different phases.