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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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17 views

Experiment with transformer: meaning of some physical quantities

I'm doing some experiments with a transformer, measuring some physical quantities. First I did an experiment with the transformer in open-circuit. I determined the voltages and currents on both ...
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1answer
78 views

Why would Discontinuous Conduction Mode be desirable for an LED driver?

I saw this press release where DCM was listed as a feature for a new Infineon driver chip. Source: led-professional.com I'm involved in LED driver design for Horticulture where DCM is undesirable....
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120 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 ...
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1answer
51 views

Is Power Factor only relevant at rated load in Light Equipment?

As you might know, LED lamps over 25W require a minimum 0.9 power factor in Europe. I have designed a PSU for a specific LED lamp which is rated about 50W. There is a PFC-stage (crm) in order to ...
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1answer
36 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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3answers
53 views

Power determination for resistive load

I am a mechanical engineering student and i need to measure electrical output. I have some voltage and current measuring instruments. I used them to measure the voltage & current of a blower(...
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2answers
43 views

on a network analyzer's measurement what's the meaning of a negative PF?

on a 1 MVA transfomer, process in the place is plastics injection machinery. On the plotted data from an analyzer results in PF jumping from 0.998 to -0.997 (roughly) for all the measurement period ...
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5answers
153 views

Would an AC induction motor rotate if the power factor were unity?

I know about active and reactive power as a big picture. Active power is what really does the job and the reactive power circulates back and forth in and out of the system. I also know the math behind ...
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3answers
104 views

Why does low power factor make my LED bulb and clock radio flicker at 0.2 to 3 Hz?

[California, USA, regular 110 V power.] I'm reading the power factor of my "Late 2013" 27-inch iMac using a P3 P4400 Kill-A-Watt. It reads 0.95 when operating normally (60 to 120 W), but when ...
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1answer
100 views

Harmonic resonance calculation in power-factor correction

Eaton's Power factor correction: a guide for the plant engineer states, Capacitors and transformers can create dangerous resonance conditions when capacitor banks are installed at the service ...
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2answers
71 views

Filter harmonics in AC power line [closed]

I run a Toshiba Digital copier machine in my shop and the machine started showing error codes related to power issues a few days ago. This happens randomly during daytime. There were no problems at ...
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11 views

What range of power factors is used to test electricity meters under ANSI C12.20?

ANSI C12.20 is the standard used in the U.S. for electricity meters. In the contents and scope (pdf) I see that test number four involves varying the power factor of the test load and observing the ...
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1answer
198 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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2answers
64 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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1answer
50 views

Multi phase vs single phase power factors

Are there any differences between calculating single phase and multi phase power factors? I'm open to general answers, but more specifically: If PF1=P/S, does PF3=(Pa+Pb+Pc)/(Sa+Sb+Sc)? Does ...
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1answer
73 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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1answer
226 views

Why does line current equals the total apparent power divided by 3 times the phase voltage?

In this circuit with frequency of 50hz and line to line voltage of 400 V why is the current \$ I_A = S_t/3V_P\$ I don't understand the logic behind since there is one Delta connection, I understand ...
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444 views

Power factor and Harmonics associated with Electric Vehicle charging

What is the power factor associated with (typical) DC fast chargers and onboard chargers in electrical vehicles? Also, how much is the harmonic content (especially triple-N harmonics) associated with ...
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40 views

Switching power supply with PFC equivalent schematic

I need to simulate inrush current of SMPS with power factor correction. I hope that it is possible to put rectifier bridge, capacitor and, probably several additional components, to simulate the ...
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1answer
43 views

How do I solve for Capacitance in this circuit?

I know that the equivalent resistance of this circuit will be $$R_1-j/(\omega*C_x)+L_1+(R_2-C_1)||L_2$$ $$(3+.814j)-j/(4737*C_x)+[(4j)(30-8j)]/(30-4j)$$ I don't know what to do from here; I could ...
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179 views

Phasor diagram problem

I am trying to solve this problem. I tried to use phasor diagram but I did not go far with it. Can anyone help me? In the figure below a generator with a voltage of 120 volts, RMS, is feeding a load ...
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2answers
52 views

How to think about Power Factor when adding new devices to a generator

I've been tasked with checking to see if an existing backup generator will be powerful enough to handle a new building in addition to the buildings it is currently handling. First, here is the ...
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1answer
61 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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1answer
1k 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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1answer
2k views

PFC using arduino

I'm trying to make a power factor correction system using arduino. In the first i successes to calculate the PF using arduino and XOR gate Following picture is my circuit: simulate this circuit &...
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192 views

Which power factor is better in an industry -0.21 or -0.94 and why?

In the electrical panels , when i switched on-off the capacitor bank then power factor gets shifted from 0.89(lagging/during OFF condition) to -0.87(leading/during ON condition) , similarly on ...
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27 views

Device modelling

Can anyone help me model this VCOMP block highlighted in the picture. I attached the datasheets of the IC.The IC below is the UCC28180, a boost PFC circuit. I already ask at forums in Texas Instrument ...
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1answer
89 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 ...
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1answer
125 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
316 views

Pc power supply Ac in rush current overloading inverter

I have a PC consuming 400 watts hooked up to an 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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1answer
899 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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89 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?
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314 views

how to get a clean AC current waveform for power-factor calculations

I've been doing a project to figure out the power factor of a load by comparing the zero crossings of the voltage and current signals (of a AC signal) and hence finding the phase difference using an ...
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1answer
113 views

how does l6565 IC VFF function function

my question is how VFF(voltage feed-forward) pin of L6565 IC works. does it function as a multiplier like L6564 IC? in L6564, multi pin multiplies to vComp and makes input reference peak current (...
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1answer
1k views

Power Factor Correction on Generators

If a generator is loaded with appliances that have a power factor lower than .8 is it safe to use power factor correction capacitors to improve this number?
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2answers
60 views

Changing the power factor of a circuit when connected to transformer

There is a step-down transformer with a primary voltage rating of 120 volts, a secondary voltage rating of 48 volts, and a VA rating of 1 kVA (1000 VA). The maximum secondary winding currents can be ...
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48 views

What is the least input current THD that has been attained by researchers using a unidirectional boost PFC rectifier?

The flowchart shows different types of PFC rectifiers classified on the basis of topology. I have been going through the papers available at IEEE but can't find the absolute least input current THD ...
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178 views

What do all of these symbols mean on an old power factor meter?

"cos. phi" is OK, it's a power factor meter. Apart from that; from the top left, I understand "Klasse 1,5" to mean max. 1.5% measurement error, 5A to mean maximum 5A I guess. On the right, I ...
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184 views

How to control switching of mosfet in PFC boost rectifier using PI controller?

My aim is to reduce THD in the supply current and I wanna use a simple PI controller for that, to make the inductor current more sinusoidal and at the same time keep the output voltage of the ...
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2answers
180 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. ...
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2answers
145 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 ...
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1answer
973 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 ...
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2answers
1k views

Power factor of induction generator [closed]

What is the working power factor of induction generator? Is it leading or lagging ?
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4answers
432 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 ...
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6answers
2k 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 ...
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1answer
412 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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2answers
760 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 ...
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1answer
97 views

Boost Inductor Voltage calculations

This is probably a stupid question, but please bear with me. I'm making a boost inductor for PFC and I just wanted to make sure I'm calculating for the voltage correctly. Is the equation: \$N = \...
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330 views

Inrush current limiting circuit

For my boost PFC design that I am currentely working on, I need a current limiting circuit for the capacitor inrush current in start up, the widely used circuit in this type of applications cases is ...
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4answers
1k 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? ...