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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38 views

Vienna rectifier Matlab simulation

I am trying to simulate the following case: A three-phase source in a Matlab is connected to a Vienna Rectifier which is supposed to supply power to a resistive load of 50KW. Output DC voltage to be ...
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31 views

Does active power factor correction help with internal radiated/conducted noise?

I am choosing parts for the supply of a device. The case will be a metal chassis and there will be an AC-DC (12 V) converter module inside mounted on the chassis. The total AC power draw will be less ...
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34 views

Generator Power factor Calculation with varying Output Power

We are operating a generator (Stirling engine in particular) that outputs a certain active power in the range of 6.5-8.9 kW. The power output is adjusted with pressure variation. The electrical ...
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46 views

Boost PFC Control

I am learning the Boost PFC control, and I read this Master thesis and I have some questions I want to ask you guys. 1.)In the PFC control why we need to multiple 1/x^2, can someone tell me? I think ...
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55 views

Current sensing in boost PFC controllers

I was going through the datasheets of a few active PFC controller ICs (like this: https://www.ti.com/lit/ds/symlink/ucc28019a.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1619350669153&...
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Boost PFC with large leakage inductance

I would like to implement a boost PFC stage for an alternator that has a large leakage inductance (~40mH). When looking at the schematic, we can see that the boost inductance ...
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1k views

Need device with poor power factor

I'm looking to calibrate an energy meter. As a part of that process, I need to cheaply find a device that can create a power-factor of 0.5, in order to calculate the required phase correction. The ...
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29 views

PFC formula for calculating conduction losses across MOSFET

I am not able to demonstrate the formula above where Vin is the input voltage of the PFC, Vout is the output voltage, Po is the output power, and Rds(on) is the on resistance of the mosfet. This ...
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53 views

Power factor requirement for SMPS just above 75W

What is the power factor (PF) requirement for an SMPS or even just a standalone power factor correction (PFC) stage with a power level above 75W? I know that in some cases the customer will specify ...
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26 views

Inaccurate differential voltage measurement

I tested 3-level PFC voltage initialization event in practice using 1 x single ended probe to measure the output voltage as well as 3 x differential probes to measure the precharge voltage levels of ...
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2answers
59 views

Current values after power factor correction

I am a student tasked with correcting the power factor of an RC circuit to unity with a parallel inductor... Vrms = 240V, 50Hz R = 12ohm C = 220uF. I have calculated the inductor value by calculating ...
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61 views

Why shouldn't I use a Zobel network to improve the power factor of an electric motor?

This is a homework question, so I would prefer something that would make me think and maybe promote discussion. I understand the use cases for a Zobel network in an audio setup, but I struggle to see ...
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63 views

Finding the kVA loading after improving the power factor

This is a homework question I've been attempting. But the answer I get doesn't match with whats given and I don't understand why my method is wrong. This is the question with answers. Here's what I'...
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59 views

Calculating PF of a transformer

Consider a one-phase transformer rated at 20 MVA, 13/2 kV and 50 Hz. It goes through a short-circuit test with |V1|=11 kV applied on the primary side. During the test, the primary side draws rated ...
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When changing rotor current in alternators, the pf and inductive part of the current changes but the resistive part does not. Why is this so?

Given a current for an alternator $ I = I_R - jI_X $ When the rotor current changes, the excitation changes so the magnitude of the generated voltage changes. The current changes, but only the ...
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119 views

Impact of PFC output impedance on the regulation of a converter

I have determined the transfer function of my converter operating in closed loop configuration. Nevertheless I saw on the web that the transfer function is not the same if my converter follows a PFC. ...
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31 views

Formula for non - active power of capacitors connected in a star?

There is a common question in my coursework that we are asked to : Let's say we have an inductive 3 - phase load that consumes $$S=15 + j10$$MVA "If , we connect parallel to this load, 3 ...
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44 views

High power factor but maximum current at resonance in series RLC circuit

In a series RLC circuit, at resonance, the power factor is unity but the current is high. But since in high power factor the current drawn is low, then isn't this a paradox? High current is ...
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51 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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2answers
56 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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82 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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19 views

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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24 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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81 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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1answer
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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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132 views

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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111 views

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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1answer
153 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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1answer
56 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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58 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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139 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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1answer
52 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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2answers
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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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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62 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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63 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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1k 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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134 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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434 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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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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4answers
651 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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49 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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89 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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80 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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413 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. ...