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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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Why does reactive power change when a secondary source is connected?

When load was varying very little, PV supply was turned ON. Inverters used can give power factor(PF) in the range of [-0.8, -1] and [0.8, 1.0] Table 1 shows power requirement when only grid was ...
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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 ...
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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 ...
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Reactive vs Real Power in DC-DC Converters

I don't understand which form of power, reactive or real, should be dominant in a maximally efficient DC-DC boost converter. As the circuit charges the inductor, the current and voltage will be out ...
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Reactive Power at Slack Bus

When computing the power flow solution, we find the (1) voltage angles at (a) load nodes and (b) non-slack generator nodes, and (2) voltage magnitudes at the (a) load nodes. We can then compute the ...
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112 views

simulate a motor with resistor and inductor

I want to simulate a motor with a resistor and inductor. It means I want to connect a resistor and inductor to 1-phase or 3-phase instead of a motor. For achieving this goal I have to measure both ...
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187 views

Active Energy, Reactive Energy or just Energy?

I understand the concepts of active power, reactive power and apparent power. I am not sure I am getting the complete concept about the respective energies. I am using an energy monitor to record ...
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39 views

Static VAr Compensation

I have to design a 3 phase Reactive Power Compensation System with using only reactors, no capacitor is needed. Total capacity is 505kVAr, but 475kVAr will be done with contactors, rest (30kVAr) will ...
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98 views

Determine the power dissipated in W in the 5 Ω resistor [closed]

simulate this circuit – Schematic created using CircuitLab Excuse me for my really bad use of the schematic feature I just didn't know how to switch to the phasor domain. Anyway, I'm asked to ...
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Parallel resonant induction heater

I implemented a parallel LC induction heater using theory. I made a simple square wave Inverter providing a frequency of 20kHz to the tuned LC circuit. The problem I'm facing is that my tank is not ...
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29 views

Calculating reactive power given u(t) and i(t)

I would like to calculate the reactive power of a given two-pole which has the following voltage and current characteristic. \$u(t) = 2+5sin(\omega t)+2sin(2\omega t+\frac{\pi}{6});i(t) = 10+3cos(\...
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Active (P), Reactive (Q, D) and Apparent (S) Power from Instantaneous Power (p)

I am having a difficultly with producing \$S, P, Q \$ and \$D\$ from Instantaneous Power \$p(t)\$. Let's say that both voltage and current are clear sine waves. Then: \$p(t) = Vsin(ωt+φ_V) \cdot ...
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Calculating the reactive and active power

This is probably an easy one for you. In the following circuit simulate this circuit – Schematic created using CircuitLab I want to calculate the active and reactive power in load R2-C3. I've ...
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90 views

Reactive-Voltage (QV) Droop Curve and droop constant of Statcoms

I have a question about voltage droop curve of statcoms. I read many articles about it but I did not figure out how to calculate it and how to add droop curve in control systems. My system parameters ...
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66 views

Does Reactive Power flow between Energy storage elements in a three phase system?

I noticed that unlike the single phase ac power sources, the power in three phase is constant which means the instantaneous power is the same as the real power which is $$3V_{rms}I_{rms}\cos{\theta}$$ ...
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65 views

Reactive Power in grid side converter for Doubly fed induction generator

Does the grid side converter in a DFIG absorb/provide reactive power or is it reactive neutral? Also, what can we say about reactive power exchange in the rotor side converter?
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68 views

Nonzero current at voltage zero-crossing when consuming reactive power

In a circuit that consumes some reactive power, the current waveform indicates current flow even when the supply voltage is at the zero crossing. This seems paradoxical since there cannot be current ...
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116 views

No battery rechargeable led light

I want to make a tiny led glow for 10 minutes once charged by induction. I want the entire PCB not greater than 20x20x5mm. Is it possible? I have come up with the following circuit, I don't know if it ...
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231 views

Why does a fault lead to increased reactive power demand?

When we have a fault, say on one line out of three, the reactive power demands increase, which leads to voltage instability if the source can't provide it. My question is, what causes reactive power ...
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298 views

How to pick a capacitor to adjust loop compensation caused by reactive load?

I do wish to add a voltage regulator between a Li-Ion battery pack and a 36V 220W rated mid drive pedalling assist motor with integrated controller. The caps of that controller have a 63V rating. ...
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331 views

How does a conventional generator produce only reactive power?

For a class that's rather far outside of my background, I am reading a paper about supply-demand balance in an islanded microgrid. The active power demand of the whole system can be met with ...
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595 views

Calculate the total max power dissipation in CLASS AB push pull for reactive loads

As worst case we can assume in reactive load the same power dissipation with the resistive part of that load. Thus for a 8 ohm impedance with phase angle of 60°, we can use \$R_L=0.5*R_{Reactive}=4\...
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When transformer rating is in kVA, why load is mentioned in WATTS?

The transformer rating is given in kVA, but the load connected is always considered in watts. Why? Eventhough, the load active power is represented in watts it has some reactive power, right? Is ...
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74 views

How to compute active power with current

I'm working with an electric resistor (oven resistor) and I want to compute the active power with an embedded system. My idea is to use a current probe around the phase wire to acquire the current ...
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304 views

Why reactive power is constant?

In a transformer let us assume a load is connected consuming certain active power; say 5000 W. Now if we put a different load of low power factor consuming same amount of active power, now here the ...
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113 views

Tool for measuring Real and Reactive Power [closed]

I am currently doing a project where I need the Real power (P) and Reactive power(Q) measurement for a Refrigerator. I understand that if I can measure AC Voltage(V) and AC Current(A) for the ...
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493 views

Reactive power overcompensation causing voltage increase at generator buses?

Consider the following system below, nine buses, 3 loads and 3 generators. From my understanding of reactive power, lagging power factors (per unit voltage less than 1) causes the reactive power to ...
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59 views

Power reading in different places

Currently, I have a software which able to read voltage, current, active power, apparent power and reactive power from appliances which I assume the readings should be approximately same even though I ...
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3answers
75 views

Determining V and I from limited data

I am the recipient of an incomplete set of data for several 120 volt, single phase, AC drive systems driving induction motors under various loads. The measurements were taken at the AC voltage source. ...
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1answer
1k views

Power factor improvment c/k ratio

All power factor improvment controller has a setting c/k ratio. Their manual says it is the lowest step of capacitor bank. It controls switching threshold. But how what is its significance?
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413 views

reactive power and battery drain(in inverter)

if the load of an inverter(using a battery) is a pure reactive load, will the battery be drained ( neglect the efficiency of DC/AC conversion)?
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2k views

Does reactive power of induction motor vary with load?

I know that the power factor of an induction motor varies with load and is very low at no load and high at full load, but does the reactive power vary as well? If so, how much can it vary?
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227 views

Voltage Control of PQ Bus

After running power flow solution using Newton Raphson, I have been trying to vary the voltage of a PQ bus by adjusting the reactive power at bus. If my desired voltage is higher than actual, then I ...
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44 views

Correcting harmonics for power factor correction

Is it recommended to use LINE REACTORS to mitigate harmonic issues on a power distribution system if there are power factor capacitors installed?
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179 views

Transmission line problem

I will first write the problem followed by the equations I'm given and then explain what troubles me. A 3-phase transmission line of 50 Hz and nominal voltage 400kV has the following per phase ...
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1answer
267 views

Reactive power … consumption?

This question is from an exam to this year official university access tests (see here, in Catalan): In Catalan: Connectem en paral·lel una reactància capacitiva de 100 Ω i una reactància ...
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alternator reactive power

I'm tying to calculate the change in reactive power of an alternator with the change in its real power input. P=EV/Xs sin(d) is the real power output of the generator. Q=EV/Xs cos(d) - V^2/Xs is the ...
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Calculating the real and reactive power of a transmission line

I have a single machine connected to an infinite bus with the following parameters: Sending end power = 3.75MW RL=5.18 ohms XL=130 ohms VS (Generator bus)=161kV VR (Infinite bus)=161kV Sending end ...
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76 views

Is it a disadvantage for a generator to supply both resistive and reactive current to its load?

Suppose The power network 1 has a resistive load and therefore the current supplied by the generator 1 to the load is purely resistive. The power network 2 has a resistive + inductive load and ...
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What is the power factor of a classical power supply?

What is the power factor of a classical power supply ? I mean a transformer, rectifier and filter capacitor. Is it constant ?
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How can AC current be limited with reactance?

Since resistor dissipate electrical energy by converting it to heat, while capacitors and inductors store electrical energy I believe using reactance will waste less energy. My source is 225 V, 50 Hz....
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2k views

Why does HVDC consume reactive power

So many academic papers quote the following fact: "A line commutated converter in steady-state operation inherently consumes reactive power of about 60% of the DC power transferred." I do not want to ...
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What power relationship (between active and reactive powers) should I expect from a CNC machine?

I have collected loads of power data from a 3-phase CNC machine and it all looks like this: The 3-phase active and reactive powers can be seen above, as well as the Q (reactive) - P (active) ...
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how is it possible that an inverter absorb reactive power

It's always said that reactive power is interpreted as magnetic field in motors (or transformers) it can also be the electric field in capacitor, but where does an inverter "store" that reactive ...
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When simultaneously running a stepper motor and an induction motor, the stepper stalls when the induction motor is braking. Ideas?

I am running an induction motor and a stepper motor simultaneously through a driver board I designed. The board has a dual H-bridge for driving a bipolar stepper motor, and an inverter for driving the ...
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170 views

Using Reactive vs Real Power to Manage Distribution System Voltages

This is my first post. The introduction of photovoltaics (PV) on the electrical distribution system creates changes to real power, resulting in voltage fluctuations. Those voltage fluctuations can ...
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4answers
1k views

How do reactive currents cause power transfer?

I read in 'The Art of Electronics': Power factor is a serious matter in large-scale electrical power distribution, because reactive currents don't result in useful power being delivered to the load,...
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504 views

Calculate capacitance i.a. via reactive power

The ampermeter of the following circuit shows 10A (AC) and the voltmeter 220V (AC). Furthermore its known that: $$ cos\varphi=\frac{2}{3} \\ f=50Hz $$ I calculated the following: $$ P=UIcos\varphi =...
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455 views

power factor correction and switched power supply efficiency

When it comes to switched power supplies, is the power supply efficiency affected by the presence of a power factor correction circuit? In my understanding power supply efficiency is estimated by ...
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721 views

How can a parallel capacitor improve the power factor of an inductive load?

In phasor or vector diagram, a capacitor that is parallel to the supply can improve power factor. I know this is practically true but I don't understand the mathematical equation: The total impedance ...