Power factor correction devices

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.

7 Comments

  1. Bernard Heber says:

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    Reply
  2. 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.

    Reply
  3. 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.

    Reply
  4. 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.

    Reply
  5. 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.

    Reply
  6. tomi says:

    I use WordPress for this blog.
    The reason why the style looks different than most blogs is that I use a custom made WordPress theme.
    Very many blogs seems to use the standard WordPress themes or other free or inexpensive themes.

    If you want to stand out on the design, you need to pay attention to theme design.
    Wordpress based blog can look the same as most similar blogs, or something completely different, depending on the style you use.

    Reply

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