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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3answers
198 views

What is the reason of undesired peak current in PFC non-isolated boost converter?

I have attached inductor current waveform of PFC boost converter. After the particular current level, an undesired peak is coming. I have done some study and thinking it might be because of inductor ...
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3answers
8k views

Calculating the True Power Factor in non-linear loads

In my circuit I am taking in 60 Hz 120 VAC from the power company and hooking it up to a AC/DC non-linear switching buck converter I am designing. I know that: true power factor = (displacement power ...
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1answer
309 views

Control of interleaved boost converter

In a school project we will try to implement a control system for a boost power factor correction (PFC) converter. The converter circuit can be seen below (http://www.ti.com/lit/an/slyt517/slyt517.pdf)...
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1answer
584 views

Generator shutdown on leading power factor

I am having some issues in one of my projects. We have installed a generator in a building, where power factor is leading and -kvrs are shown on controller display. We know that this building is ...
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1answer
25 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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1answer
46 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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31 views

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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1answer
39 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
33 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
20 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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1answer
32 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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2answers
56 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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1answer
37 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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4answers
12k views

Why is capacitor placed in parallel for power factor correction?

I understand that to correct the power factor you have to choose a capacitance such that the reactive power from the circuit is cancelled by the reactive power of the circuit using this method. ...
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1answer
2k 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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2answers
1k views

Why power factor correction for Capacitive load is more difficult?

When we want to correction power factor of a motor(inductive load) its simply can done by adding an capacitor in parallel with the motor but its not possible to correction power factor of an ...
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2answers
19k views

Why do power companies never bother residential customers about power factors?

I recently bought a Kill-a-Watt meter to measure power consumption of my devices. This was just a fun project for me. I put this on my Mac-Mini to see power consumption during various usage states - ...
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1answer
547 views

Power Factor Correction Circuit (LED lighting)

I've been researching how to design power factor correction into an agricultural LED lighting system. My client requires at least a 0.95 power factor. I'm planning to use PWM controlled buck ...
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1answer
158 views

Grid tie inverter power factor

After installing a grid tie inverter (GTI,) the power factor dropped from 1 to .85 over the last week. My loads are a combination of inductive and resistive. I have an option of setting my GTI to ...
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2answers
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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3answers
163 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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1answer
99 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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2answers
242 views

Active Power Factor Correction Operation Mode

I'm trying to design a SMPS power supply with potentially widely varying loads, from say a watt or two to ~150W, and I want to include Active PFC because of the medium power load, as well as to use ...
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1answer
111 views

Does using electronics with poor power factor affect the pulse power capability of a generator rated for a certain KVA?

The situation is such: There is a multi-pole, three-phase, permanent magnet generator (rated for 100 KVA, let's say) that feeds into a simple diode rectifier with a capacitive/DC Voltage load (...
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47 views

PFC Current waveform Misunderstanding

Here is a current waveform that I found on an application written by TOSHIBA. I supposed the waveform is correct. Nevertheless there are some points that I do not understand. Here is the schematic ...
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1answer
101 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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2answers
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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3answers
1k views

Power factor relation with load

I was reading about power factor in electronic devices and I found charts showing that usually the power factor varies (usually decreases) with the load. So if you have a device that either works with ...
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40 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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35 views

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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4answers
186 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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1answer
35 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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63 views

Transformer Leakage Inductance and power factor

How does transformer leakage impedance affect power factor? Or how does the X/R ratio of the transformer change the power factor ?
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1answer
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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2answers
70 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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33 views

Power in balanced three phase systems

I was solving the following exercise And got the a) and the c) correct: \$\ Iline = 14.6 - 5.95j (A) \$ \$\ power factor = 0.926 \$ I turned the delta connection into a wye connection and got: \$...
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3answers
172 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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1answer
3k views

Effect of load on power factor in induction motor

I got stuck in an MCQ question. Which is as following : Q.1) power factor of a squirrel cage induction motor is : (a) Low at heavy load only (b) Low at light and heavy loads (c) Low ...
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35 views

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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70 views

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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19 views

L6561 PFC based SMPS - will it operate properly when running the whole unit off HV DC supply?

In a near-aircraft fixed ground application I have to run a special, multi output SMPS which has a L6561 based PFC front end. So far this SMPS was run off regular 230 V 50 Hz mains, but ...
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1answer
73 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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1answer
45 views

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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1answer
42 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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75 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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2answers
271 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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1answer
82 views

Is there anything besides power factor that determines the max CFL that can be used in a socket compared to the max incandescent for that socket?

When shopping for lamps recently, I've noticed that the sticker on the socket says something along the lines of "To reduce risk of fire, use maximum 60 watt incandescent or 13 watt compact fluorescent....
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2answers
2k views

Pc power supply Ac in rush current overloading inverter

I have a PC consuming 400 watts hooked up to a 220 VAC automatic backup 1500VA 12V dc inverter since AC grid line is not 24/7 in my country. The main problem is that sometimes when the AC power goes ...
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57 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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1answer
49 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 ...