Power factor correction devices: Can they really reduce your electricity bill? article tells that so-called “Power Saver Devices” (known by different names) are nothing but Power Factor Correction (PFC) devices that would connect to the mains and improve power factor measured by your electricity meter.
The so-called “Power Saving” device may be useful for industrial applications, where utilities charge the user based on PFC rather than real power. Such 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.
However it is important to note that utilities bill a residential user based on real power that does not factor in Power factor ( inductive load is minimum in typical home. Thus a PFC device may not reduce the electricity bill. Be careful on marketing gimmicks on this field. PFC can be useful for residential situations in the design of a backup energy system like a Home Inverter or UPS (Uninterruptible Power Supply).
Read whole Power factor correction devices: Can they really reduce your electricity bill? article to get more details. Read also article comments that correct some inaccuracies found on the article itself.
Wikipedia article Power factor has also useful information on power factor and how it is corrected. It mentions that besides power factor correction on inductive loads there are also different power factor issues with non-linear loads. Regulatory agencies such as the EU have set harmonic limits as a method of improving power factor. To comply with current EU standard EN61000-3-2, all switched-mode power supplies with output power more than 75 W must include passive PFC (built onto the device), at least.
14 Comments
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Tomi Engdahl says:
Quick PFC check
http://www.edn.com/electronics-blogs/living-analog/4415478/Quick-PFC-check-
we needed to see if the PFC function was working properly
Here was how we checked for that using an audio transformer as a test fixture.
Narendra Kumar says:
Hi, nice post got valuable information about Power factor.
Power factor improvement plays a major role in the industry, which saves lots of money and strengthens the life of the machine.
Tomi Engdahl says:
Thank you for your feedback on my article.
Tomi Engdahl says:
Power Integrations highlights importance of power factor correction at APEC 2017
http://www.edn.com/electronics-products/electronic-product-reviews/other/4458242/Power-Integrations-highlights-importance-of-power-factor-correction–at-APEC-2017
Power factor correction is the process of improving a low power factor in a facility by increasing the ratio of real (working) power to apparent (total) power.
Here is what HP says about power factor correction, especially regarding data center needs1:
Before computing and storage devices can use electrical power, the AC provided from the source must be transformed to direct current (DC) by a power supply. The term “power” is the rate at which the electricity does work, such as running a central processing unit (CPU) or turning a cooling fan. The power that the electricity provides (apparent power) is simply the voltage times the current, measured in volt-amperes (VA). There is a difference between the power supplied to a device and the power actually used by the device because of the capacitive nature at the input of the device to delay current flow.
A power supply that has a PF of 1.0 indicates that the voltage and current peak together, which results in the most efficient loading of the device. Power supplies for servers usually contain circuitry to “correct” the power factor (that is, to bring input current and voltage into phase).
Power-factor correction allows the input current to continuously flow, reduces the peak input current, and reduces the energy loss in the power supply, thus improving its operation efficiency. Power-factor-corrected (PFC) power supplies have a power factor near unity (~1), and thus are highly efficient. The use of energy-efficient PFC devices, including uninterruptible power supplies (UPSs), can lead to significant cost savings.
Many designers may try a low-cost approach to correct low power factor; that is, installing capacitors within a facility’s power distribution system. Capacitors will behave like a temporary storage bank for reactive (magnetizing) power (kVAR).
Capacitors have been used to improve poor power factors since 1917; this is 2017 and designs are “not your father’s” PFC architectures.
Tomi Engdahl says:
Power factor correction devices: Can they really reduce your electricity bill?
http://www.edn.com/electronics-blogs/beyond-bits-and-bytes/4374264/Power-factor-correction-devices–Can-they-really-reduce-your-electricity-bill-
So-called “Power Saver Devices” (known by different names) are nothing but Power Factor Correction (PFC) devices that would connect to the mains and improve power factor measured by your electricity meter. However it is important to note that utilities bill a residential user based on real power that does not factor in Power factor and thus none of these devices would really reduce your monthly bill.
The so-called “Power Saving” device may be useful for industrial applications, where utilities charge the user based on PFC rather than real power.
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.
Even though a PFC device may not reduce the electricity bill, it does not change the fact that inductive loads run more efficiently with corrected or at least improved power factors and thus means less wear and tear of the appliance (i.e., the motor since current drawn by the motor is reduced), improving product life.
One situation where PFC can be extremely useful for residential situations is in the design of a backup energy system like a Home Inverter or UPS (Uninterruptible Power Supply). Correcting the power factor from 0.65 to 1 results in a 35% reduction in the size (VA rating), thus a less expensive inverter can be chosen though power consumption remains the same.
In homes today, and particularly since Energy Star-rated appliances have hit the market, motor driven appliances like air conditioners already have an appropriate sized capacitor attached to them.
Energy Star products not only define maximum real power an appliance can draw in various modes but also define the minimum power factor the appliance must satisfy to get Energy Star certification. For example, Energy Star version 5.1 for game console/computer requires power factor to be greater than 0.9 at 100% rated output, or maximum rated output of less than 75W to be able to meet the requirements.
By purchasing another PFC and connecting it to your electric meter, you are basically adding a redundant device into your home than your appliance can use, so there is really no monetary savings by doing so and is certainly a marketing gimmick.
Tomi Engdahl says:
Is Power Factor Correction Justified in the Home?
http://www.powerelectronics.com/power-management/power-factor-correction-justified-home?code=UM_Classics02118&utm_rid=CPG05000002750211&utm_campaign=15618&utm_medium=email&elq2=437394767695470887301b35bd6e8d9c
Though PFC equipment may be warranted in industrial applications, an analysis of the energy savings enabled by this equipment in residential applications suggests its added cost to the consumer may not be justified.
Recently, you may have noticed advertisements for a device that claims to reduce your monthly home electricity bills. The advertising literature states that you are paying for the added electricity that must flow when power factor (PF) is less than “unity” within your house. But to what extent does PF influence energy consumption? And do the energy savings accrued through power factor correction (PFC) justify the purchase of standalone PFC devices?
Numerous pieces of equipment in the home are candidates for PFC. Some of these equipment types have capacitive inputs (for example, switching power supplies). However, some of the larger loads are the motor-driven appliances such as refrigerators and washing machines, which have inductive inputs.
In the instance where a circuit has a PF less than unity, more current must flow to produce the desired electrical work. This additional current flow causes more power losses in the conductors located in the walls of your house, for which you derive no advantage except for a small amount of additional heat generated
So Why PFC?
PFC devices are used in some commercial or industrial applications where a company may have a large number of electrical motors that would have a significant effect on the PF of utility transmission lines, which span much longer distances than the cables in the home. Utilities may assess commercial or industrial customers a penalty for PF significantly less than one.
Some appliance manufacturers are incorporating PFC into their finished products. The European Union’s International Electro-Technical Commission adopted the IEC61000-3-2 standard that required, by Jan. 1, 2001, all equipment needing 75 W of power or greater and less than 16 A to meet standards for harmonic generation and, thus, meet PFC requirements. Thereafter, Britain, China and Japan adopted similar standards. North America does not presently have these requirements.
Where the mechanical load is reasonably constant (e.g., an air conditioner compressor motor), a PFC capacitor can be specified to produce a desired effect. Appliance manufacturers are faced with an interesting dilemma when including PFC into their finished products. They must convince their potential customers that over the product life, energy cost savings would equal or surpass the additional initial selling price, vis-à-vis a non-PFC item.
It may be that the energy savings enabled by PFC on a global scale will, through a combination of legislation and economics, cause PFC to be incorporated universally into all electrical equipment.
Tomi Engdahl says:
Power Saver Scam EXPOSED!
https://www.youtube.com/watch?v=J86QK0Njfv4
Power Saver devices are sold everywhere. But do they actually save power?! DON’T BE SHEEP!
Comment:
bigclivedotcom
2 päivää sitten
With the new “smart” meters they can unfortunately start charging for apparent power instead of real power. And that can be done remotely. If they do that then suddenly things with capacitive droppers like time switches and will cost about 10 times as much to run and most LED lamps will cost between twice and ten times as much to run depending on their circuitry.
Sadly, a simple capacitor won’t fix most electronic power factor issues. But it’s a nice case and can be used as a shocker. (but with a much bigger capacitor)
Tomi Engdahl says:
Is Power Factor Correction Justified in the Home?
https://www.powerelectronics.com/power-management/power-factor-correction-justified-home?PK=UM_Classics03119&utm_rid=CPG05000002750211&utm_campaign=23836&utm_medium=email&elq2=d501b95cfbd2409cb2bdc27482a2b79b
Though PFC equipment may be warranted in industrial applications, an analysis of the energy savings enabled by this equipment in residential applications suggests its added cost to the consumer may not be justified.
A survey of the Internet for PFC equipment revealed that PFC items, both inductive and capacitive, were advertised on eBay. The prices ranged from $5.99 to $2000. Some of the lower-priced units did not contain a description of whether the items were solid state, inductive or capacitive. A Square D PFC capacitor in a mounting box, the PFC4005FR, was listed at $49.99.
Tomi Engdahl says:
Power saver plugs just got a bit darker
https://www.youtube.com/watch?v=iy1P08aj73k
These power saving plugs have been around for a while. They possibly started life as a genuine filter plug for softening significant mains transients, but then found a new scam market being sold as power savers, often sold using fraudulent claims of reducing your home electricity bill by a significant amount. (They don’t.)
Things have taken a slightly darker twist recently, with adverts involving pictures and video of young kids, with fabricated stories of how they invented this miracle power-saving device, but refused to be bought out by “big-oil” so that everyone could benefit from their technology.
When these adverts have appeared on platforms like Facebook they have inevitably resulted in a flurry of gushing comments from people who have become emotionally involved with the story of youth heroism and have bought several units to support them.
In reality these units are probably being drop shipped from Chinese warehouses, which will also happily supply their long established product to you if you search on eBay for “power saver”. The going rate on eBay is around £5 shipped (about $7). If you buy from the rogue marketers they will mark that up significantly if you even get the products. (Facebook has a terrible history of marketing scams where people have been duped out of their hard earned money.)
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