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The amount of reactive power supplied by a shunt capacitor is proportional to the square of the line voltage, so the capacitor contributes less under low-voltage conditions (frequently caused by the lack of reactive power). This is a serious drawback, as the supply of reactive power by a capacitor drops when it is most needed; [11]
Reactive power does not do any work, so it is represented as the imaginary axis of the vector diagram. Active power does do work, so it is the real axis. The unit for power is the watt (symbol: W). Apparent power is often expressed in volt-amperes (VA) since it is the product of RMS voltage and RMS current. The unit for reactive power is var ...
In electrical circuits, reactance is the opposition presented to alternating current by inductance and capacitance. [1] Along with resistance, it is one of two elements of impedance; however, while both elements involve transfer of electrical energy, no dissipation of electrical energy as heat occurs in reactance; instead, the reactance stores energy until a quarter-cycle later when the energy ...
In induction generators, the reactive power required to establish the air gap magnetic flux is provided by a capacitor bank connected to the machine in case of stand-alone system and in case of grid connection it draws reactive power from the grid to maintain its air gap flux. For a grid-connected system, frequency and voltage at the machine ...
In practice, the prime mover (a power source that drives the generator) is designed for less active power than the generator is capable of (due to the fact that in real life generator always has to deliver some reactive power [2]), so a prime mover limit (a vertical dashed line on the illustration) changes the constraints somewhat (in the ...
The reactive power like the real power must balance (that is the reactive power produced on a system must equal the reactive power consumed) and can be supplied from the generators, however it is often more economical to supply such power from capacitors (see "Capacitors and reactors" below for more details).
Angle notation can easily describe leading and lagging current: . [1] In this equation, the value of theta is the important factor for leading and lagging current. As mentioned in the introduction above, leading or lagging current represents a time shift between the current and voltage sine curves, which is represented by the angle by which the curve is ahead or behind of where it would be ...
An HVDC thyristor valve tower 16.8 m tall in a hall at Baltic Cable AB in Sweden A battery charger is an example of a piece of power electronics. Power grid designer in front of a newly installed 880kV thyristor valve array A PCs power supply is an example of a piece of power electronics, whether inside or outside of the cabinet.