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Power-User

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Home Electricity Saving via Adding Power Factor Capacitor

06/10/2021 3:50 AM

Hallo Guru,

Could I use industrial 440v 3 phase power factor correction capacitor bank 1.5kvar connect to my house 240v single phase to have some energy saving on my monthly electricity bill? 2 phase of capacitor bank connect to single phase.

My house full loading 2.2kw

Thank you & Regards

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#1

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/10/2021 4:55 AM

Domestic customers usually do not get charged for low power factor in the tariff. So, while a small amount of energy might be saved, equal to the sum of all the reactive heating loads in the conductors downstream of the meter, it can be awfully difficult to justify the investment needed to do this.

Which is why it isn’t done everywhere.

Draught excluder and improved thermal insulation are much easier to justify, especially at higher latitudes. Replacing tungsten lighting with LED will give an exceptional return on investment too. So it is these things that need to be done first.

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#3
In reply to #1

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/10/2021 6:00 PM

Series Resistance (SR) losses within the capacitors themselves will all but nullify the tiny amount of reduced ohmic heating losses in the conductors... so there is really no energy savings worth considering.

So to reiterate for the OP: there is no point in doing this for a residential user, unless (and this is rare for residential users), you utility is charging you a penalty for having poor power factor. THAT is the only reason to add PFC capacitors, and if you connect them when there are no induction loads running, you then run the risk of voltage damage to your devices by having a LEADING power factor. So even if you get the PFC caps for free, making them work right without killing your electronics by separating them into banks and controlling them with a PF controller and contactors will cost you more than it is worth.

Just say no...

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#2

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/10/2021 12:16 PM

I'm pretty sure residential power meters measure True Power (KW), and not "Apparent Power" (KVA)

http://electronicsbeliever.com/electric-meter-works/

"Power Factor Correction

So a power factor correction device typically includes nothing but a capacitor that is to be connected in parallel as the additional load. The effect of these two opposing reactances in parallel is to bring the circuit's total reactive power close to zero.

This correction, of course, will not change the amount of true power consumed by the load, but it will result in a substantial reduction of apparent power, and of the total current drawn from the 230 Volt source.

This is the principle behind most of the Power Saver devices available in the open market. As explained earlier, this does not impact the real power, and since residential consumers are billed on real power this has no impact on the monthly bill."

https://www.edn.com/power-factor-correction-devices-can-they-really-reduce-your-electricity-bill/

The power company is losing money because of the losses due to the Reactive Power in the power lines, so I suspect they would appreciate the savings. But if you are paying for KW and not KVA, correcting the power factor shouldn't affect your power bill.

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#4

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/11/2021 2:57 AM

In a former life I used to test electricity meters. A set current was put through the meters at their nominal nameplate rating 10 amp for a 10-60 amp meter. 10Amp is the meter and 60amp is the maximum load.

A meter used to consist of a potential coil, energised from the mains, a current coil through which the load flowed. For power factor correction a brass or copper shorting plate was screwed across the gap of the potential coil and was trimmed to get the meter to read at 0.5PF. The disk revolutions were controlled by shunting the pole faces of the control magnets so at 10 amp it did the correct revolutions for the current. The disk was marked around its periphery with numbered divisions so a +/- indication could be read. Now there are newer solid state versions but out in the real world many old style meters still serve their masters.

The same current went through a standard test meter and the meters under test were adjusted against the calibrated standard. Test were done at unity power factor, 0.5 lagging power factor, a minimal current, 12W for a 10 amp meter to ensure that low loads were picked up and 50amps for 5x current.

So if you use a power factor correction capacitor all you do is decrease the current flowing in the wiring and decrease the I2R losses which are measured by the meter, however the use will reduce the current through breakers providing the load is lagging PF, of best effect on old style fluorescent lights where the cap provides leading PF to counter the lagging PF of the old inductive ballasts. Is effective on old transformer style welders but the capacitors can suffer premature failure from ripple current heating.

Now with 3phase meters the same was done. A phalacy that was floating around that if you were welding on a 3phase circuit with 3 separate meters one was seen to go forward quickly, one normal speed and one backward but don't get happy the one going quickly made up for the one going in reverse. The use of 3 phase meters evened this anomaly out. Of course some of the meters had a detent that only allowed forward movement.

I have seen all sorts of tricks to slow meters like putting large magnets on the wall behind the meters but then that could weaken the control magnets and the meter go faster. Drilling holes in the case and resting something on the disk was another trick as well as blowing iron filings in so they caught on the magnet and slowed the disk.

Then there were the brave souls who drilled a hole through the mounting and through the insulating case into the line side and connected a wire with a self tapping screw. Still if the meter suddenly slowed between readings the meter reader would flag a problem and the meter would be changed. Hard to pull a meter off the wall when it has a screw through the back though.

Was always hard to prove as the perp had to be caught in the act of intrusion.

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#5

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/11/2021 3:17 AM

Important to remember:Capacitors charge to the PEAK VOLTAGE.This is 1.414 X RMS value.

Capacitors must be matched properly to the circuit to prevent over voltage.

I once was called to an industrial plant where motors were constantly failing.

The problem turned out to be a leading power factor,caused by removing a lot of 3-phase motors from the plant.

The PF capacitors had not been adjusted accordingly,and the motors were receiving very high voltage,causing failures.Removing the proper amount on capacitors from the substation solved the problem.

Utilities usually compensate for an entire neighborhood by placing capacitors on the poles feeding them.Look closely and you will see them sometimes.

No need to add any capacitance to your home..you do not have enough inductive loads to worry about,and they are intermittent;Refrigerator,freezer,clothes dryer,maybe a welder,grinder,or other tools.

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#11
In reply to #5

Re: Home Electricity Saving via Adding Power Factor Capacitor

08/26/2021 6:50 AM

I called a seller of these devices and confronted him with the facts.

He got very agitated,called me a "Know-it-all" and hung up,cursing and mumbling the whole time.

This device is meant for the general public that know nothing,or very little, about electricity.

PT Barnum said:"No one has ever lost money by over estimating the stupidity of the American public."(No offense intended to the general public).

Pet rocks come to mind; Then funerals for pet rocks,insurance for pet rocks, and the list goes on.

My dear old pappy said: "If you throw a rock into a pack of dogs,the one that gets hit will always holler."

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#6

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/19/2021 8:52 AM

Seen this advertised Voltex. Must be a rip-off.

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#7
In reply to #6

Re: Home Electricity Saving via Adding Power Factor Capacitor

06/20/2021 11:30 AM

Total

complete

scam.

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#8

Re: Home Electricity Saving via Adding Power Factor Capacitor

07/01/2021 8:39 PM

NO

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#9
In reply to #8

Re: Home Electricity Saving via Adding Power Factor Capacitor

07/05/2021 10:13 AM

No what?

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#10

Re: Home Electricity Saving via Adding Power Factor Capacitor

08/26/2021 5:12 AM

It is easier to justify boiling only the absolute minimum amount of water in a kettle in pursuit of making a cup of tea.

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