# 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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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 ...
140 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 ...
28 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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### 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 ...
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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### 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 ...
178 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)...
224 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 ...
56 views

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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### 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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### 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 ...
110 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 ...
321 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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### 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 ...
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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### 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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### 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 ...
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?
453 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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### 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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### 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 ...
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....
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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### 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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### 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 ...
256 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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### 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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### 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 ...
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?
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 (...
311 views

### Can over-excited synchronus motor operate on lagging power factor?

All of the Electric Machines literature I'm using states that over-excited (back emf E> supply voltage V) synchronus motor will operate on leading power factor (one of them states that it may also ...
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### 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 ...
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### 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 ...