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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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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Power Factor Correction: Facing a trouble while converting AC to DC

I am Designing AC to DC power supply. For Power Factor Correction I am using LT1248 from Linear technology, It works in Boost CCM operation, and the schematic is designed for 400VDC output using ...
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34 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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226 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 ...
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55 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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56 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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49 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?...
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90 views

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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34 views

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 ...
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38 views

Readings for a current transformer reversed

What would happen to the measured values of a circuit (real power, apparent power, power factor, current) if I install a current transformer "backwards"? Usually a current transformer has some ...
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How can we make a load that has configurable power factor for 230V AC?

We are hoping to create a lab for students at our university that requires them to measure the power factor and correct for it. We are working with 230V AC and have a maximum power of 300W. We were ...
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50 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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98 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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184 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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54 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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41 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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64 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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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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261 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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138 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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203 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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79 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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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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325 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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73 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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53 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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115 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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320 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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695 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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44 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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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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71 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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2k 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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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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235 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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105 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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181 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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400 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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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?
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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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380 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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118 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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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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61 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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201 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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237 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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211 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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156 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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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 ...