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Anonymous Poster

How does a capacitor improve power factor?

06/11/2008 7:31 AM

I know what is improving power factor. But i want to learn how does a capacitor produce reactive power for inductive motors?
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Anonymous Poster
#1

Re: How does a capacitor improve power factor?

06/11/2008 8:19 AM

http://www1.eere.energy.gov/industry/bestpractices/pdfs/mc60405.pdf
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T Man
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#2

Re: How does a capacitor improve power factor?

06/11/2008 8:20 AM

Capacitors improve power factor by drawing current 180 degrees out of phase with the 90 degree lagging reactive current component of the system. By reducing the reactive component of power the load current drawn by the system is reduced

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Anonymous Poster
#3
In reply to #2

Re: How does a capacitor improve power factor?

06/11/2008 8:11 PM

T Man,

Good explanation! I think you should use the word "inductive" in place of "reactive." Both inductors and capacitors are reactors (ie. have reactance). Inductors have inductive reactance and capacitors have capacitive reactance.
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ALSTEF
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Join Date: Oct 2007
Posts: 5
#4
In reply to #2

Re: How does a capacitor improve power factor?

06/12/2008 2:28 AM

Sir,

I couldnt really understand the explanation for the correction of the lag by using the capacitors. Why should a capacitor improve the power factor???? or for that matter why should a inductor create this lag.

what happens if there is a phase shift b/n the current and the voltage. Can unity p.f.(no phase difference b/n voltage and current) be likened to the two individuals(current and voltage) applying their forces(their max.) to lift an object at two different instant.Something like that.

I know this question sounds childish but all this all the documents or the answers that i have got on this topic has not me understand this well.

Please help me understanding it Sir.
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Anonymous Poster
#5
In reply to #4

Re: How does a capacitor improve power factor?

06/12/2008 6:13 AM

Hi,

Go to the basics. The vector relationship V & I shall be out of phase by 90 deg. A resistor if included in the circuit will mainatin an UPF. That means it will be in phase with Volatge. A capacitor will be for leading the PF and the Inductor is for lagging the PF. i.e inclusion of Capacitor & Inductor will be either out of phase with volatge (Lead & Lag).

N.Suresh
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#11
In reply to #4

Re: How does a capacitor improve power factor?

11/23/2022 1:39 AM

That’s interesting, because neither could Anonymous Poster #1.

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Anonymous Poster
#6

Re: How does a capacitor improve power factor?

06/12/2008 9:51 AM

Thank you to all. But i do not understand completely.
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bettytefe
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Join Date: Sep 2009
Posts: 1
#7
In reply to #6

Re: How does a capacitor improve power factor?

09/18/2009 8:28 PM

take inductive loads , like motor, lighting ballasts, transformers! in each case the voltage maximum occurs before the current maximum because of the wire and magnetic field created around each wire, which is called voltage leading the current. watch out this is the characteristics of the load. how much the voltage leades the current is refered to as power factor.

Capacitor increases the power factor, letting the maximum current to occur closer to the time when the voltage is at a maximum. Capacitor may be thought of as a battery that stores and releases current to improve the power factor, meaning to minimize the phase difference between voltage and current.

hope this helps

thanks
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Anonymous Poster #1
#8

Re: How does a capacitor improve power factor?

11/11/2022 2:43 AM

How does a capacitor improve power factor? - Search (bing.com)
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Haymaker
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Join Date: Feb 2020
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#9

Re: How does a capacitor improve power factor?

11/11/2022 9:31 PM

Inductance knocks the peek current out of time with the peek voltage. This invalidates Ohm's law. The capacitor resets those peeks to the same time. And reaffirming Ohm's law. True power.

The lag of current comes from the spin of current in an inductor. The current spins around the wire, instead of down along it. Radial current, instead of axial current. The current has a longer path than the voltage, and takes more time. The velocity of current never stops or slows, it just changes direction. The voltage never changes axial direction and completes the circuit first......this only applies to voltage fed circuits.

Current lag is not a delay, only a change in direction. The change in direction adds path length, causing a longer travel time. The proper value of capacitance, can unwind that coil current, causing a axial current, back in time with the voltage. A capacitor spins current in the opposite direction that the inductor does. Reactance is spin. And one spin can cancel the other.

You can see this dynamic for yourself with ferrofluids.

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SolarEagle
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#10

Re: How does a capacitor improve power factor?

11/11/2022 10:56 PM

You feed the capacitive current into the inductive load to align the waves thereby correcting the power factor, tuning the current to match the load...

https://passive-components.eu/an-introduction-to-capacitor-based-power-factor-correction-circuits/

https://circuitdigest.com/tutorial/what-is-power-factor-and-how-it-affects-your-energy-bills

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