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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81 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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46 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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84 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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39 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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28 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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146 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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30 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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60 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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86 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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32 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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66 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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119 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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30 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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64 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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17 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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70 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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44 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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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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65 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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109 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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37 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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44 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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279 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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69 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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91 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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53 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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431 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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206 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 ...
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38 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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78 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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37 views

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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54 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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137 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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297 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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56 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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48 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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75 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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44 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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487 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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193 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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324 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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95 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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504 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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101 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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63 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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166 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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391 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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1k 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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47 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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87 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 ...