Active Power and Reactive Power

Active (true or real) power is that which is produced by a generator, Reactive power is that which is dissipated in a load which has either a capacitive or inductive component.

The degree of difference between the two is determined by the power factor of the load. Power factor is notated in an ascending scale from 0 to 1 with 0 being lowest and 1 being highest or unity. The higher the Power factor, the closer together the true and apparent power dissipation in the circuit will be.

An inductive or capacitive load will cause some of the current to be stored in the load and then returned to the circuit a fraction of a second later. This causes an increase in power (apparent) over what is really required (true) to drive the load. Many supply authorities charge consumers extra for their power if the power factor of their load is low, because they have to allow for the extra currents required to operate the low power factor equipment.

True power is normally expressed in Kilowatts (kW)whereas apparent power is expressed in kilovolt amps (kVA).

A generator will have a degree of inductive reactance which will affect power factor, and which is often corrected to close to unity by the addition of capacitance into the circuit.

There would be numerous sources of better information on the internet for your further education on this subject.

Oh my lord...

Quite.

Er, what was so difficult to understand in the Wikipedia article on this topic that warrants editing, please?

Power it is energy [mechanical work] produced [or consumed] in a time interval. Power may be electrical, mechanical, thermal, chemical and other. It can be transformed from a form to another. Only active electric power has this property.

As was mentioned above, reactive power is not actually a power but a conventional one.

The electric current produces magnetic field around the conductors[ more inside and outside a coil-inductor, transformer ,motor and so on].The magnetic field is not an active energy [but may be a potential one-as mass or gravity field].If it is steady[without changes] does not consume or produce energy. Therefore D.C. system is not influenced by magnetic field.

If it changes in amplitude [as in 50-60 Hz a.c. system]will require power for a half of cycle and will return the power in the second half, so the total power required or returned will be 0.

Since this phenomenon will increase the peak [both senses] and the effective value of the current one has to take it in consideration. So the current split [virtually] in active-producing the power-and reactive [non-producing power].The second lags the first by a quarter of a cycle.

The measured current value multiplied by supplied voltage value is not then the actual power-as in d.c. system-but it is a value defined as "apparent power" and in order to take in consideration the imaginary current and reactive power are attached to an imaginary number=square root of (-1).This way facilitated developing an entire theory with very important practical results.