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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19
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2answers
17k 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 - ...
13
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3answers
7k views

How does active power factor correction in computer power supplies work?

I'm not looking for very detailed explanation (although it would be welcome). I'm more looking to intuitively understand how it works. Basically in computer PSU I have input followed by filters ...
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2answers
6k views

Are typical computer power supply units leading or lagging power?

Computer power supplies often have "power factor correction" features which raise the power factor in use to levels close to resistive loads (1). I'm curious what, in the absence of power factor ...
9
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1answer
3k views

non-linear load (rectifier) and power factor

I read that power factor shows how much there is the apparent power, which circulates between power lines and the load and does nothing but heats up the transmission lines and transformers in them. ...
7
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3answers
1k views

Capacitor exploding in a paper plant

Two years ago I was in an internship in a paper plant in the Superintendence of Electrocontrol, in the area of maintenance of electrical equipment. Well, they had a problem regarding some capacitor ...
6
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2answers
3k views

Capacitor Bank Rating

I need to know why capacitor banks are rated in KVAr rather than Farads? Suppose I have one capacitor bank of 10kVAr which is for a rated voltage of 400V. Will this bank provide the same reactive ...
6
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1answer
1k views

Compact Fluorescent Lamp Load Calculations

I help build/wire up large illuminated carnival/parade floats, and in the past we have used around 11,000 40w/60w GLS BC light bulbs in festoon sockets, powered by a 800KVA 3 phase diesel generator. ...
5
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4answers
2k views

Why does the voltage across the DC-link capacitor in a boost PFC circuit usually equals 400 Volt?

In a boost PFC circuit connected to the grid (230Vrms,Europe) the DC-link voltage is usually regulated to 400 Volt. Why is that? Is that because it is efficient to boost it to that particular voltage? ...
5
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2answers
999 views

Can adding inductive load really reduce mains power consumption?

I have recently bought one of the cheap mains power meters (EL85-2042A to be precise) to monitor power consumption. It's really helpful when I need to know where my electricity bill comes from, or ...
5
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2answers
4k views

Is PFC compulsory for AC/DC converters 75W and above?

I’m reading the user guide for a Microchip reference design of a 300W AC/DC converter. Section 1.2 starts with these requirements: A conventional SMPS must implement PFC if it draws more than 75 ...
5
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1answer
1k views

why boost PFC topology is the most used?

While searching about power factor correction topologies, the topology I came across almost all the time was the Boost PFC topology, and I'd like to know why? why is it the most widely used one, in ...
5
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1answer
2k views

What is the capacity of capacitors in this power supply circuit?

Imagine the following circuit with two capacitors and diodes acting as passive PFC. My question is what is the capacity of these two capacitors? I mean compared to a circuit with just a single ...
5
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2answers
7k 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 ...
5
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1answer
11k views

What does a power factor of a generator means?

When I was reading the nameplate of a small 5KVA generator, I found that the power factor is mentioned. It was 0.8 . Is this the minimum power factor that the generator can handle? or Is it the power ...
5
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1answer
203 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 ...
5
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1answer
638 views

Underground cables and resonances in range of frequencies

Is that true that underground cables with no power factor correction have resonances in range of frequencies which leads to multiple zero crossing distorted waveform? But why? Is that is because it ...
4
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4answers
2k views

How do you calculate the power factor of a power supply?

Is it possible to measure or calculate the power factor of a power supply without using expensive tools? If so how?
4
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3answers
119 views

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 ...
4
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1answer
522 views

Power factor correction in a simple phasor circuit

I've been having a bit of trouble with a relatively simple power factor correction problem involving a simple circuit in the frequency domain (\$f=50\,\text{Hz},\omega=2\pi f=100\pi\,\text{rad/s}\$). ...
3
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3answers
7k views

How do residential analog and smart meters measure power?

I'm building my own digital meter in order to upload the data to a SQL database; up until now I know that there are several parameters being measured into a digital watt-meter: volts, current, ...
3
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3answers
231 views

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 ...
3
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1answer
50 views

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?...
3
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1answer
109 views

supply power factor of a residential transformer

A transformer winding is generally more inductive than resistive thus there is a considerable phase difference between voltage and current, so wouldn't the supply power factor be very very poor in ...
3
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3answers
1k views

How to apply passive PFC on low side of transformer in power supply?

I have a low power power supply, built with a 60Hz 120v/12v 0.3A transformer. It will have an ordinary diode bridge and capacitor filter. What I want to achieve is reduction of current/magnetic field ...
3
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1answer
101 views

Power factor basics

I am confused about how the power factor is defined for an unbalanced 3-phase load? Wouldn't it make much more sense to ask for a particular phase of the unbalanced 3-phase load?
3
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2answers
157 views

Should I do PFC? [closed]

I came across this question:why boost PFC topology is the most used? Now I ask myself, should I do PFC too? My system is a servo with diode bridge rectifier and different current ratings. Very price ...
3
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1answer
6k views

How to measure power factor cos phi with an Arduino?

according to How does one measure the power factor? I can measure the power factor (cos phi) by comparing the zero point crossing of Voltage and Current. This is clear. The problem I have is what if ...
3
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1answer
210 views

Does the DC portion of an inverter experience the Apparent Power consumption of the AC part?

If the AC portion has no load, then the DC portion sees it as an inductive load I assume. So does power factor come into play when calculating the DC wattage consumed? Let's say AC is 100V 0.1Amps no ...
3
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2answers
415 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 ...
3
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1answer
426 views

Determine best capacitor for inductive load

If I know the Watts, the Power factor, the VA, or anything the standard Kill-A-Watt meter can measure, how can I determine the best capacitor to use for a heavily inductive load? I have some ...
3
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1answer
188 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)...
2
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4answers
464 views

Output voltage ripple

I am trying to understand the boost PFC and how its controller works. The output voltage always contains a voltage ripple depending on the capacitor value, but shouldn't the voltage loop reduce this ...
2
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3answers
345 views

Why is PFC done 'equipment-side'?

I have only a basic understanding of power factor correction, but I am curious why it is necessary for manufacturer's and their customers to be concerned with ensuring a high power factor, other than ...
2
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2answers
846 views

How do capacitors improve power factor without destroying the capacitor?

Can anybody help explain in simple terms how adding capacitors to a 120/240/higher AC power circuit helps improve power factor without blowing up the capacitor? I'm familiar with capacitors in DC ...
2
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3answers
4k views

How to compensate for leading power factor?

Since my job is related to led drivers and ballasts i get confused with some questions. I see that the capacitor that is placed after diode bridges decreases the power factor and when we remove it we ...
2
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6answers
3k views

Ways of estimating phase shift

I have a system that's sampling two 50Hz sine waves at 1kHz. What's the best way to estimate the phase shift between the two? The measurements are somewhat noisy and the sampling period is not very ...
2
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2answers
254 views

Why electric company sell the electricity according to real power?

Electric company in some countries apply financial penalty for electricity consumers which have power factor lower than 0.9 If electric companies charged customers for apparent power, people would be ...
2
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2answers
10k 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. ...
2
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2answers
223 views

Measuring power factor on sinusoids

I'm not sure if this is the best forum for this or whether stackoverflow mightn't be better, but I'll ask here and see what people think. I have a system measuring 50Hz voltage and currents at 1kHz. ...
2
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4answers
4k views

Power factor correction for LED lighting on a generator

I'm the electrician for a club that builds an illuminated carnival parade float, and historically we've lit our float using around 10,000 x 40w incandesant lamps powered by a 800kVA 3 phase generator. ...
2
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1answer
545 views

ATX - replace passive PFC to active

I have some ATX PSU with passive PFC (huge coil with capacitor). I also have some active PFC from other ATX that based on L6561 IC. This psu will handle odroid xu4 board and few led strips based on ...
2
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1answer
80 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....
2
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2answers
3k views

what does “overcompensation” mean?

I read that using fixed capacitors in power factor correction in low voltage has some disadvantages like : Overcompensation (correct past unity) can someone explain that to me?
2
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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 ...
2
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2answers
434 views

Help with complex power and power factor correction problem

I'm having a bit of trouble trying to understand what is being asked of me in a relatively basic circuit theory question involving complex power and power factor correction. Now, part (b) and (c) ...
2
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1answer
58 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 ...
2
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0answers
196 views

Large negative current spike in N-Channel MOSFET source when turn-off

I am working on repairing a power supply board of a LCD TV (200W power), more specifically, the PFC section (active power factor correction). See schematic (adapted from here): I've replaced some ...
2
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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?
2
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1answer
120 views

How does one compute the ripple currents seen by an active PFC output capacitor?

Suppose one is designing a single-phase power-factor-corrected power supply, with a known average current load: The ripple current seen by the output capacitor is critical. If that current is too ...
1
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1answer
1k views

Why is inductive instead of capacitive power factor preferred?

My question is why it is easier to correct an inductive power factor with a capacitor and not a capacitive power factor with a coil?