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Ahmad Kishki
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Complex power has two components the "active" and the "reactive". I am comfused. What is the physical interpretation of the complex component?
Also what is the reactance?
Also what is the reactance?
Power = energy/time. For reactive power this means in first semicycle of sine oscillation the energy is delivered from a source to a load, and in next semicycle returned back from load to the source.Ahmad Kishki said:Can you please elaborate, what does oscillating power mean?
So called reactive power is due to the energy that's stored in the reactive components. Personally, I don't like the term as I think it is used to describe something 'the opposite' to the power that is dissipated. It isn't really Power at all. All you need is to follow the Maths and avoid the name.Ahmad Kishki said:Can you please elaborate, what does oscillating power mean?
NTW said:The German version of the Wikipedia has a good article: 'Blindleistung':
http://de.wikipedia.org/wiki/Blindleistung
It has its counterpart in English, but not as detailed...
sulemanma2 said:Because my understanding of reactive power is that it keeps bouncing back and forth between source and load and never gets used up.
anorlunda said:See my post #5 in this thread about the power reversing direction for half of each cycle, I think that's what you mean by bouncing back and forth.
But that's not the whole story, a load such as a motor must be supplied with some reactive power as well as real power. It "consumes" both kinds. Reactive power is also consumed by the inductive impedance of the power lines causing the voltage to drop at the far end of the line. In some cases we must provide capacitors near the ends of those lines to replace those lost VARs and keep the voltage up.
Industrial customers are charged penalties by utilities if their loads draw too much plus or minus reactive power. That is called low power factor. Regarding your question though, those loads "consume" reactive power.
Devices called synchronous condensers are like generators that make zero real power but they make a controllable amount of plus or minus VARs. They are used to help control voltage. We also use shunt reactors (inductance between line and ground) or shunt capacitors to add plus or minus VARs to help control voltage.
So, the Primary purpose of the grid is to supply real lower, but reactive power is a necessary secondary need. Management of reactive power is the primary means of controlling voltage magnitude on the grid.
sulemanma2 said:I think I am confusing reactive power with the fact that in an AC current, electrons are flowing back and forth. So I am thinking with the electrons, the reactive power is also going back and forth with the electrons and never gets used up. Only the Real Power gets used up. Maybe this thinking is incorrect?
Also can their be a AC current that has no reactive power?
anorlunda said:With AC power, the electrons go back and forth with both real and reactive power.
sulemanma2 said:...
Also I keep hearing about reactive power that causes heat losses?
...
Wouldn't that technically mean that the reactive power converts into active power, when it is lost as heat?
Reactive power is the power that flows back and forth between an inductive or capacitive load and the source. It is measured in units of volt-amperes reactive (VAR) and is responsible for creating magnetic and electric fields. Active power, on the other hand, is the power that is used to perform work, such as turning a motor or lighting a bulb. It is measured in watts (W) and is responsible for producing heat, light, and mechanical motion.
Reactance is a measure of how much a circuit resists the flow of reactive power. It is measured in ohms (Ω) and is determined by the type of load and the frequency of the current. Inductive loads have a positive reactance, while capacitive loads have a negative reactance. The greater the reactance, the larger the amount of reactive power required to maintain the same voltage and current in the circuit.
Reactive power can cause inefficiencies in power systems by increasing the amount of current needed to deliver a given amount of active power. This results in higher losses in transmission and distribution lines, leading to higher operating costs and potential voltage drops. Utilities may also need to invest in larger equipment to compensate for the reactive power, which can be costly.
Reactive power can be managed and controlled through the use of devices such as capacitors and inductors to either supply or absorb reactive power. These devices, known as reactive power compensation devices, help to maintain the voltage and reduce the amount of reactive power flowing through the system. Automatic Voltage Regulators (AVRs) and Power Factor Correction (PFC) controllers are also used to regulate the reactive power and improve system efficiency.
Reactive power and reactance can be seen in various real-world applications, such as inductive motors, transformers, and fluorescent lighting. For example, in an inductive motor, the reactive power is required to create the rotating magnetic field that allows the motor to run. In transformers, the reactance helps to regulate the voltage and current. Fluorescent lighting also requires reactive power to create the electric fields that produce light.