Questions tagged [power-factor-correction]

A circuit that compensates the reactive characteristics of a load to make behave as close as possible to a resistive load in order to maximize the power consumption efficiency.

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40 views

Is my solution to this power factor question correct?

I'd be very thankful if it would be possible for someone to check my solution to this question and highlight any mistakes which I may have made in the working. I have checked through it myself several ...
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Boost PFC inductor selection [closed]

I want to make a boost PFC. I need a 260 uH inductor which can handle a current (|20sin(2pi*50t)| A + harmonics). As the peak current in one cycle is ~20A, I found an inductor (https://in.element14....
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39 views

Power factor in a power system

Will a system necessarily have an increase or decrease in power factor with a change in frequency of the system?
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79 views

How can Kill-a-watt show .1A, 12VA, but 0 watts?

I'm trying to verify whether a 10W aquarium heater is failing. It has a safety fuse that renders it permanently inoperable if it overheats by running unsubmerged, which is suspected in this case. My ...
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3 phase 208v leg balance and observed KVA

I have a cluster computer system in a small server room, fed by an 80 kva capable double conversion (480v 3-phase in, 208v single phase out) UPS. This UPS has an LCD display showing voltage, leg ...
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23 views

Finding the capacitor value for power factor correction

I know the formula of how to find the capacitor value but id need to find the supplies value first and I don't know how to do that. I have the Is=21.60A and phase angle=43.95. question: A recent ...
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28 views

How can a boost PFC (Vienna rectifier) lower the voltage?

I found a Vienna rectifier circuit as a PFC. Output range: +350...+500VDC and -350...-500VDC. Input: 400VAC (three phases). To begin with, I simulated a basic three-phase rectifier: Here's the 561V ...
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56 views

Confused with the formula for Power Factor Correction

The formula provided in my lecture notes: $$C=\frac{Q_c}{\omega \:V_{RMS}^{\:2}}$$ Where $$Q_c=Q_{old}-Q_{new}=P\left(tan\left(\theta _{old}\right)-tan\left(\theta _{new}\:\right)\right)$$ Such that \$...
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What is the significance of UPS output Power Factor?

A UPS's output rating is shown as (2000VA/1800W). I understand that the p.f. 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 ...
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Power Factor Circuit

I am currently working on an energy meter that requires to know the Power Factor in order to get the Actual Power in the circuit. The circuit diagram attached shows my circuit diagram and it is ...
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APFC C.T.Position [duplicate]

We installed on grid solar plant. Before installation P. F. was always maintained to 0.99 by capacitor banks(APFC panel). But after solar connection is varies and goes down up to 0.16. APFC panel CT ...
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Power factor down after solar connection

We installed solar plant in factory. After that power factor goes down to 0.16. Normally it never goes below 0.85 in history even if we keep APFC off. We always maintained it to 0.99. Note - Main ...
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96 views

What capacitor do i need for a 3phase 50HP motor

Hi currently have a 3phase 50HP motor with an 80% Power factor I need to bring it up 95% power factor. What capacitor size would i need to achieve this. If someone can show the formulas they used that ...
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35 views

Use two 250V series cap in APFC instead of single 400V

I have a EVGA 500W PSU with an APFC which is causing spike noises, presumably from the APFC or main switching as they both run in sync controlled by the CM68000TX combo apfc switching PWM chip Noise (...
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53 views

Capacitor in parallel decrease my power factor

I made a DIY solar system including a batteries and a pure sine-wave inverter, and I wanted to increase the power factor (which is typically 0.6 ~ 0.8) with a laptop power adapter load. After ...
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CCM PFC - Duty Cycle and Pout Misunderstanding

Suppose a PFC working in CCM. Vout is hold constant thanks to the duty cycle. Pout is also constant over the time. Suppose the input rms voltage Vin_RMS drops ! For a CCM boost PFC, the duty cycle is ...
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95 views

PFC - Output capacitor Formula

I do not understand exactly how the below formula has been found. The formula allows to calcul the output capacitor (Cout) of a PFC boost converter working in CCM : Here is the definition of the hold ...
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37 views

PFC - High Frequency Input Capacitor Formula

I do not understand exactly how the below formula has been found. The formula allows to calcul the high frequency input capacitor (Cin) of a PFC boost converter working in CCM : I particularly do ...
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21 views

Drain oscillations on PFS7329H

I have 100V/200W PSU with PFC and I see attached waveform on drain of PFS7329H controller. How can I get rid of it? PSU seems to work fine, but I see EMI issues.
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34 views

Improved power factor effect on national grid

I was wondering what the effect would be on the national grid for if a large power consumer was to improve its power factor. I know that it would reduce demand but is there any other effects?
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59 views

Power factor correction (totally lost)

We have a 3 phase electronic motor with a 'useful' power 4kW. Its efficiency is 80% Currents on the lines are equal in all three phases, and they are lagging behind the voltages by 30 degree. We need ...
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42 views

The proof of \$PF_{p}=cos\theta_p=sin\theta_s\$

There is a Series RC circuit ,which power factor is \$\frac{\sqrt{3}}{2}\$,now if i modify this "Series" RC circuit to "parallel" RC circuit,then what is the value of power factor of this circuit? ...
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62 views

What should i be concerned about when powering a 10A load from 120VAC

I have something that needs to be powered 25 feet away from the wall(120V). The load requires 10A of current. I'm worried that line inductance would deform my input voltage and lead to a non ideal ...
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602 views

How can excitation be used of an alternator to control the power factor?

Looking for ways the excitation of an alternator can control its power factor?
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114 views

PFC controller - How does it work?

I would like to better understand how a PFC controller works, especially PFC which work in CCM mode. I found the following documentation from International Rectifier: https://www.infineon.com/dgdl/an-...
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256 views

What would cause a power meter to report negative vars?

I have some digital power meters at work that we installed due to previous concerns of voltage instability. The voltage instability has been corrected and these are now primarily used for monitoring ...
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43 views

Where should power factor correction and active harmonic filter connected?

After mains electricity meter, there is an isolation transformer (delta to star) and all load is connected to the secondary of the isolation transformer. We plan to install a power factor correction ...
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Compensating Reactive Power in MV using LV capacitors

We have a plant including high power medium voltage (6.3Kv) motors. Motors are fed from the 20Kv line using a 20/6.3Kv transformer. We want to compensate reactive energy in MV side to reduce reactive ...
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385 views

Why does nMOSFET keeps blowing up?

I have designed a Boost PFC circuit, But upon switch on transistor is getting blown up and fuse is burnt. So I removed transistor and just connected source to ground. the circuit worked fine. Then I ...
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39 views

Power Factor Correction Controller IC limits

I've been considering throwing in an active PFC circuit into a high power PSU (about 5kW max surge at 240Vrms, 1400W typical), and while looking for an easy to use, low passive count controller, I ...
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66 views

What will happened to the electric/electronic equipment if we supply with different Cos Phi?

In some part of our country, the cos phi is 0.9 while in some other is still 0.8. The higher the cos phi the better. The power is belong to government (say the name is MAINS). Different cos phi is ...
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88 views

Why do we need to know power factor in electrical loads? How does it affect the loads?

From my level of understanding, power factor is \$\cos(\phi)\$, \$\phi\$ means angle between voltages and currents. I thought from this any mismatch of angle between voltages and currents, loads will ...
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76 views

Pump power factor OK on mains, but low on generator

I'm working on a submerged pump application, running on 415V three-phase. I don't know for sure, but I believe the pumps are only a few KW. The customer is saying that the pumps run fine when the ...
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265 views

What's the role of the capacitors in this AC circuit?

I've been around electronics for a lot of time but I really didn't understand how capacitors work in an AC or DC circuits. I know capacitor has a big role in smoothing the output of bridge rectifier. ...
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Conduction Mode in PFC

At a Power-Factor-Correction (PFC) circuit, Why mostly using Continues Conduction Mode (CCM) for high power applications, ex. above 300 kW, and using Boundary Conduction Mode (BCM) or Discontinuous ...
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Why does rectifier output is showing DC instead of pulsating DC

I am using below circuit for PFC. Before connecting coupled inductor's auxiliary output to the IC's Vcc, I wanted to make sure that it is coming properly or not. So when I probed the red dot in the ...
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74 views

PFC required in China?

Is Power Factor Correction required in China? I am designing a high power, >3kW power supply and need to know to what power factor it needs to meet.
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What can I do on the bench to determine if a power supply does or does not add back a PFC (Power Factor Correction)?

I'm given a AC to DC power supply with only the inputs and output specified. It was probably made after 2000, and the ENERGY STAR program mandate to add PFC correction to power supplies may or may ...
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44 views

What would happen to the turn-on transient if I add a capacitor in parallel to a transformer?

I have a welder with a big air gapped transformer. Input specs: 220V, 3200 W active, 25 A total (cos Phi 0.56). Output specs: at full load 110 A welding current. I haven't checked whether output is DC ...
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83 views

PFC boost converter is not stepping up the voltage

I am making a PFC circuit for AC-DC converter. I am facing a weird issue. As per my design the output of the circuit should be 390VDC, but I am getting 311VDCrms with ringing (overshoot 360V, ...
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699 views

What is the purpose of a mains X2 Security Capacitor and how to determine its value?

simulate this circuit – Schematic created using CircuitLab I am evolving an existing circuit which has a 230VAC input. The 230VAC has multiple loads: Transformer followed by rectifing circuit; ...
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171 views

How does at low power factor impedance (p.f=R/Z) (if R is constant ) increases while current also increases?

Impedance is equivalent resistance of circuit having resistive and reactive components so if we keep R constant and increase inductance than Z will increase and power factor will going to decrease as ...
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58 views

DC Chopper Drive for Brushed DC Separately Excited Motor

I have a 6 pulse SCR drive, driving a large (1000KW, 750VDC) DC Separately excited DC Motor. In a typical SCR drive, the power factor improves with speed, and if the drive is to be run at 50% speed ...
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Why aren't non-isolated DC-DC converters made for high wattage applications?

I am new to electronics. I am presently studying DC to DC converters. One thing I noticed is that most of the people are using isolated stepdown converters like half bridge, full bridge, or resonant ...
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107 views

How does a negative power factor look when it is graphed?

How does a negative power factor look when it is graphed? How will this impact apparent power versus true power versus reactive power? And how do we interpret this as per power dissipated versus power ...
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147 views

Adding an additional motor to a load

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 ...
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Can we apply maximum power transfer theorem to SMPS rectifiers?

Thevinin and Norton equation simplifies BJT and MOSFET analysis leading to the hybrid pi models. Can we apply the same concept while analysing an AC-DC Converter with PFC and PSFB full bridge topology?...
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What is a power factor correction choke (PFC choke) and how does it work?

They Exist This Link at Newark displays "Power Factor Correction Chokes", which I did not know existed. I have a linear motor which I suspect really needs power factor correction. Please tell me ...
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Free Piston Stirling Engine Tuning Capacitor - Series Vs Parallel

Why is a tuning capacitor placed in series with a free piston stirling alternator rather than parallel with it? I am accustomed to seeing power factor correction capacitors placed in parallel in ...
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How to estimate the power consumption of a motor when running at low load

I am trying to calculate the electrical power cost-saving of reducing the amount of time a machine runs idle (when the motor is running unloaded). From the meter data, the amps when idling is about ...