# Questions tagged [reactive-power]

Reactive power (measured in vars) is present in a system containing reactive (inductive or capacitive) components and can be either produced or consumed by different load/generation elements. Though "imaginary", the reactive power has great physical significance and is essential to the operation of the electrical system as a whole.

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### Voltage magnitude estimation in DC power flow [closed]

I have a following engineering porblem. Consider a power flow problem for a power system and assume we have solved AC power flow for the whole network and obtained results. Now, imagine, I want to ...
20 views

### Can reactive current in an AC circuit dissipate through another resistive load which is connected parallel in same circuit?

Two loads are connected in parallel to an AC circuit, one is inductive and the other is purely resistive. As per the nature of an inductive load, it will return the reactive power at end of each half ...
68 views

### Where does the RF power go that is sent to a reactive portion of an antenna?

The impedance of an antenna can be lumped-represented as Rr (radiation resistance), Ro (ohmic resistance), XL (inductive reactance), and XC (capacitive reactance). The incident power from a generator ...
73 views

### System of First Order ODEs for a Parallel RLC Circuit

I understand the behaviour of an RLC Circuit in Series can be modelled by the equation: $$L \frac{d^2Q}{dt^2}+R\frac{dQ}{dt}+\frac{Q}{C}=0$$ Which can be represented by the system of First Order ...
50 views

### How to find the active (real) power of source A of this circuit?

What is making difficult here for me is the fact that the two voltage sources are in series (or I think that they are). This is something which I did not face before. I am well aware of why Source A ...
1 vote
64 views

### Reversal of power through a electric transmission line

From my undergraduate classes I know that active power flows from the bus with the higher power angle $\delta$ to the bus with a lower power angle. If I want to reverse the direction of power flow I ...
59 views

### Interpreting Changes in Software Energy Consumption During the Day: Seeking Insight on Patterned Peaks and Valleys

My group and I are currently studying the energy consumption of software as part of our master's degree in computer science. Specifically, we are looking at how to measure it accurately and interpret ...
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### Short circuit analysis

Im given the next distribution line with a generator and a load The generator is set at $23\,kV$ the line impedance is $9.5\Omega +j19.055\Omega$ and the aparent power is $1.5MW+j2MVars$ in the ...
1 vote
430 views

### What does mean if there is P+ and Q-?

If in a circuit there is real power positive and reactive power negative, what does mean in terms of power flow? I undestand that the real power is produced in the generator/source and goes to the ...
51 views

### What's the meaning of three-phase reactive power of a three-phase device in balanced sinusoidal conditions?

I'm trying to make physical sense of the three-phase reactive power (a.k.a. total reactive power) for a three-terminal or four-terminal three-phase device (e.g. an AC motor, an AC generator, a load) ...
471 views

### Is reactive power periodic in nature? What is the exact difference between active power, average power, and real power?

Consider an RC circuit which is supplied by a sine source $$v(t)=V_m\cdot \sin(\omega t)$$ The current through the circuit will be i(t)=I_m\cdot \sin(\omega t+\phi) \\ \phi=\arctan \left(\dfrac{1}{\...
2k views

### Reactive power in AC circuit

What is meant by reactive power in AC circuits? Power is joules per second. Real power is the energy dissipated in the resistor per second. What is meant by the reactive power? Does this mean the ...
2k views

### What is the significance of UPS output power factor?

A UPS's output rating is shown as 2000VA/1800W. I understand that the power factor here is 0.9, but the device or load I will connect to the UPS might have pf<0.9 or pf=1 (for light bulb.) From my ...
112 views

### Reducing reactive power by using a resistor

I have a school exercise that goes like this: Voltage is 230V. Frequency is 50Hz. Inductor is 400mH. How big of a resistor should be added with the inductor (in a series) to reduce reactive power by ...
1 vote
255 views

### What are the exact meanings of reactive and apparent powers? Do we say they are supplied or consumed?

(The following doubt is from the topic of Sinusoidal Steady-State Analysis of electrical circuits) I understand the meaning of real power - it is the average power consumed (or delivered) by an ...
642 views

### Using capacitors to reduce reactive power

I have been trying to understand the concept of reactive power in power systems. From what I have read so far, I understand that any inductive load like a motor needs some reactive power to function (...
1 vote
675 views

### Can battery inverters output reactive power?

This inverter manufacturer's Paper Bad Power Factor? – A reason to oversize your inverter mentions that "inverters can generate reactive power without using any active power." Can battery inverters ...
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### In a transmission line, does the real current interact with reactive impedances?

simulate this circuit – Schematic created using CircuitLab According to the diagram above, if real currents do not interact with reactive impedances, then reactive loads should not worry the ...
727 views

### How does oscillation of reactive power take place between source and load?

I have come to read that reactive power is that power which is constantly oscillating between the source and the load. Can anyone please explain this to me? Suppose an AC source is connected with an ...
1 vote
427 views

### What is meant by average power in AC circuits?

I read that "The average power is the power averaged over a cycle or number of cycles." I know that the average value of power for both active and reactive power is a constant number. Buy I am ...
66 views

### Instantaneous and active power in an ideal switch powered by real source and squared wave

This is a somewhat theoretical question, but one that has some impact on power theory. The circuit in the figure is composed of a real DC source (with non-negligible internal resistance) and feeds a ...
287 views

### What is the required VA rating of the transformer in this LTSpice power supply?

I have this circuit that I'm going to build, including the transformer. It is a simple power supply, with RC filters and one choke, I know all the voltages and currents. Because I will design, wind ...
1 vote
338 views

### How does energy dissipates in a purely reactive circuit?

Suppose in a home, power factor drops to zero. It means that the circuit becomes purely inductive. If the energy meter is connected at incoming power supply point,will the energy meter still keep on ...
328 views

### Understanding equation for the quality factor of an RLC circuit?

In my textbook for a course on Circuit Analysis I came across an equation for the quality-factor of an RLC circuit. However, I don't quite understand their reasoning. The explanation that follows is a ...
526 views

### Is there a mathematical proof that reactive power regulates voltage?

So after studying the power triangle and trying to conceptualize real power and reactive power, I seem to have come across a contradiction, at least in my own head. Most explanations disregard ...
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### Calculating reactive power on kVAr?

I think I understand how to answer this question but am missing how to do a certain part which stops me from getting their. For this question this is all I know how to do. cos-1(0.31) = 71.94° ...
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### What is the source of reactive power generated by the alternator?

We know an alternator or in general any source of energy does not generate energy but converts one type of energy into some other usable form. An electric generator produces both real and reactive ...
1 vote
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### Why transformer is heating without load [closed]

I'm working as technician in computer store and I have a lot of scrap transformers . Most of them small and have 6-8 pins .I wonder, can I use them for my projects ? If I remember correctly these ...
348 views

You have a 500kVA load with a power factor of 0.6 lag. You add an additional synchronous motor with an input of 80kW and max power factor of 0.8 leading. Determine the reactive power and the overall ...
1 vote
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### Example of Electrical Apparatus that draw leading VARS and Electrical Apparatus that draw lagging VARS [closed]

I understand that an AC inductive circuit will draw lagging vars while a capacitive AC circuit will draw leading vars (ELI the ICE man), but what are some examples of real-life electrical apparatus ...
2k views

### What is the direction of negative reactive power

In a R+1/(jwC) load (AC)voltage lags current with θ degrees. Reactive power Q is negative because sin(θ) is negative. My question is how can a capacitive load deliver power to the source wich is ...