Power Factor, and its possible application to the Hobby

[sid]

Power Factor Correction, and its possible application to the hobby

> Power dissipated by a load is referred to as true power. True power is symbolized by the letter P and is measured in the unit of Watts (W).

> Power merely absorbed and returned in load due to its reactive properties is referred to as reactive power. Reactive power is symbolized by the letter Q and is measured in the unit of Volt-Amps-Reactive (VAR).

> Total power in an AC circuit, both dissipated and absorbed/returned is referred to as apparent power. Apparent power is symbolized by the letter S and is measured in the unit of Volt-Amps (VA).

> These three types of power are trigonometrically related to one another. In a right triangle, P = adjacent length, Q = opposite length, and S = hypotenuse length. The opposite angle is equal to the circuit's impedance (Z) phase angle.


http://searchcio-midmarket.techtarget.c ... 19,00.html
http://www.pcguide.com/ref/power/ext/basicsPower-c.html
http://en.wikipedia.org/wiki/Electric_power

S = I * E

where S is Apparent Power, I is Load current, and E is Load voltage


To determine the reactive power triangle quantity, we use the Pythagorean Theorem “backwards,” given the length of the hypotenuse (apparent power) and the length of the adjacent side (true power):

Q = sqr_root(S^2 - P^2)


The ratio between real power and apparent power in a circuit is called the power factor. Where the waveforms are purely sinusoidal, the power factor is the cosine of the phase angle (φ) between the current and voltage sinusoid waveforms. Equipment data sheets and nameplates often will abbreviate power factor as "cosφ" for this reason.

Power factor equals 1 when the voltage and current are in phase, and is zero when the current leads or lags the voltage by 90 degrees. Power factors are usually stated as "leading" or "lagging" to show the sign of the phase angle, where leading indicates a negative sign.

http://en.wikipedia.org/wiki/Power_factor

Power Factor = P/S

where P is the true power, and S is the apparent power


Since P=V*I, and I=V/R, then P=V^2/R

P = V^2/R

... solving for the value R...

R = V^2/P



Given the Formula... w/x = y/z
then wz = xy and/or w = xy/z

To substitute real numbers... 1/2 = 2/4
then 1*4=2*2 and/or 1 = (2*2)/4

In Ohm's Law, R = V/I
then V(1) = IR

Note: In any real number/integer multiplied by 1 is the same as the number/integer given.


Capacitive Reactance Xc

http://en.wikipedia.org/wiki/Reactance

where f is the Line voltage frequency (in our case, it's 60Hz)

... Xc is the capacitive reactance in ohms,

... C is the capacitive value in Farads

I will replace the symbol in the formula with pie

Xc = 1/(2piefC)

... solving for the value C...

C = 1/(2piefXc)


Now, enough with the formula mumbo jumbo and proceed with an example. Shall we...

Here's a pic of the power meter output on my tank's return/transfer pump RIO2500 courtesy of the good gentleman Mr.

Obet Carlos (much appreciated brudah for stopping by at my place ).



From the reading, we can enumerate some variables for our mathematical formulas...

Power = 27.8 watts

Ampere Load = 0.251A
Input Voltage = 236.3V
Frequency = 60Hz

Total Power = volts * ampere
True Power = volts * ampere * power factor

By getting the Total Power value, the result would be 59.3VA

Power factor is True Power/Total Power, and the value is 0.469. Rounding off, the power factor of my tank's RIO2500

is 0.47. Not good, but it's typical.

Using the formula of the capacitive reactance Xc, to perform power factor correction, I would need a power/starting

capacitor with a value of 2.49 uF.


Here are the other reading we got...

Sunsun 6W


Sunsun 12W


RO Skimmer pump rated at 18w


2 x Osram 72w powering a single tube of 4ft T5-HO


2 x Osram 72w powering a pair of 2ft T5-ho tubes


Generic 55w powering a single 4ft T5HO


Ikhea 32w powering a single 2ft T5HO


Ikhea 22w powering a single 2ft T5HO




Cheers!

[jackryan]

[obet_carlos]

[jackryan]

[sid]

@Obet: Oo nga, napansin ko yong power factor function pero hindi ko na pinindot. Naisip ko, ico-compute ko na lang.

And that is true, that whether to add a capacitor to correct the power factor, which also lessen the input current, the true power stays the same because it is what the device requires to operate. But the million dollar question is... do Meralco or other power utility companies charge us by computing the "true power" or the "total power"? Are those electricity meters measure the True Power or the Total Power being consumed by all appliances and devices in our homes? (True Power is the power dissipated by a load or device, while the total power are both dissipated by the load/device and absorbed/returned to the load.)

For example, when you use magnetic ballast to drive a T5 tube, you will notice that after sometime, the ballast would get very hot, almost impossible to touch without getting burn. I believe that "heat loss" is the extra power absorbed by the load (magnetic ballast). That is also applies to an AC/Dc converter compared to a switching power supply.

A couple of months ago, I have decided to replace all magnetic ballasts with eballasts of high PF from all of the lighting fixtures in my place. This is to see if my electricity bill will reduced. No changes has been made on my tanks (didn't add or removed any pumps/lights), AC and other electrical stuff usage were the same as usual. And came the next bill, I got about 400 pesos reduction. So I thought, not bad for a small experiment.

And yes, my plan is to scout some starting capacitors at Raon or nearby places and use it in my experimental tank. Test it first with a single pump and see if it's stable for a couple of days/weeks. Then if I'm comfortable with the said experiment, I can apply it to some of the pumps in my tank. Either I will fail or succeed, I think it's worth a try.

OT: Obet, nakalimutan kong ibigay yong suhol ko sa yo. Pag balik mo bro, paki-remind ako.


@JR: Thanks bro. I believe the consumption reading captured in the power meter is pretty much accurate. It's typical for pumps to have a low power factor (PF). I was assuming before the reading that I'll be getting a PF of 0.6, but I was surprised when I got a result of 0.4+ on most of the pumps.

Problem that I see with the "energy saving device/s" being sold at the local market is that "it's just too good to be true". Correcting power factor of a specific device (or a group of devices/appliances for that matter) requires to gather specific data, such as the ones from the power meter. From there, you can compute the necessary capacitance value so that the final power will be close to unity.

And yup, that's the purpose of this thread bro... that is to find out weather or not this little experiment is beneficial to us (electricity bill reduction), and to come up with the required capacitor for our tanks' pumps, and stuff.


Cheers!

[obet_carlos]

[sid]

[trggerman]

[sid]

[nanokiper]

[wolfpak]

this is a good read

[sid]

[obet_carlos]

[sid]

Just came across with Wikipedia about KWH Meters, and I quote...

"Modern electricity meters operate by continuously measuring the instantaneous voltage (volts) and current (amperes) and finding the product of these to give instantaneous electrical power (watts) which is then integrated against time to give energy used (joules, kilowatt-hours etc). The meters fall into two basic categories, electromechanical and electronic."

http://en.wikipedia.org/wiki/KWh_meter


@Obet: I have no idea what LT capacitors are. Perhaps Wolfpak knows something about it?


Cheers!

[Flexi2009]