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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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### 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 ...
18k 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 - ...
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 ...
1k views

### Transformer VA Ratings, Power factor, and Pulsed current

What exactly goes into a transformer's VA rating? At a fundamental level it seems that there has to be a limit to what the VA rating can represent. For example if I draw 2 Amps-RMS from the secondary ...
872 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 ...
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? ...
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 ...
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, ...
210 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 ...
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 ...