Power Factor
April 7th, 2011 | 
Author: Power Factor
Power Factor deals on Amazon:
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Power Factor Workout-Maximum Power, Endurance And Size Gains I’ve worked for years to create brief, efficient workouts. But I’ve heard from many people who tell me they don’t care as much about quick workouts as they do about building more muscle power, endurance and gaining as much muscle size as possible. Even if that means longer workouts or more trips to the gym. The Power Factor Workout is the answer to people who need – or just want! – more … |
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Power Factor Training : A Scientific Approach to Building Lean Muscle Mass $16.95 Bodybuilding experts Peter Sisco and John Little present a revolutionary new system for building maximum muscle in a minimum amount of time. Power Factor Training emphasizes very heavy overloading of the musculature and long rest periods between workouts, resulting in amazing gains in size and strength. This astounding guide details the proven physiological principles of the program, answers spe… |
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THE SECRET PLUS – THE ULTIMATE LAW OF ATTRACTION; Multiply the power of the Law of Attraction by a factor of 5-10 by adding SECRET INGREDIENTS! $9.99 When I was thirteen I discovered this marvelous affirmation that was supposed to achieve wonders. What I was supposed to say was……”Day by day in every way I get better and better”. I was to repeat this over and over every time I thought of it. After 6 months I started to notice a very slight improvement.And it is the same with the Law of Attraction if you apply it in the conventional manner. I… |
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Genuine Dell XW605 250w Small Form Factor (SFF) Power Supply, For the Dell Inspiron 530s, Inspiron 531s, Vostro 200(Slim), 200s, 220s, and Studio 540s Small Form Factor (SFF) Systems, Identical Dell Part Numbers: XW604, XW784, XW783, YX301, YX299, YX303, 6423C, K423C N038C, H856C, YX302, Compatible Model Numbers: DPS-250AB-28 B, 04G185021200DE, PS-5251-5, TFX0250D5W $28.05 Replace your faulty Dell power supply quickly with one of our Genuine Dell replacement units! Dell 250w Power Supply for select Inspiron, Vostro, and Studio SFF or Slimline systems. Connectors: 1x 24-Pin ATX Connector |
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Genuine Dell 250W Power Supply PSU for SFF Small Form Factor Slim Inspiron 530s, 531s, Vostro 200s, 200 (slim only), 220s, Studio 540s Identical Dell Part Numbers XW605, YX301, XW604, XW784, XW783, YX299, YX303, 6423C, K423C, N038C, H856C, YX302, XW602 Compatible Model Numbers: TFX0250D5W, DPS-250AB-28 B, 04G185021200DE $28.50 Genuine Dell 250w Power Supply for For the Dell Inspiron 530s, Inspiron 531s, Vostro 200 (Slim), 200s, 220s, and Studio 540s small form factor (SFF) systems. Connectors: 1x 24-Pin ATX Connector; NOTE: Buyer will receive one of the compatible part numbers listed above…. |
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Silverstone ST45SF 450 watts SFX form factor power supply $53.99 ST45SF is compatible not only with chassis that use SFX power supplies but also in smaller ATX chassis with the included adapter bracket. Despite its small size, the ST45SF has features that one would expect from an elite ATX power supply such as 80 PLUS Bronze level of efficiency, temperature controlled fan, 50℃ temperature rating, and reliability for 24/7 operation. Enthusiasts oriented featur… |
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Griffin Technology PowerJolt Micro (Flat) 2A x 1 USB Power Charger for iPod/iPhone/iPad (Black ) $11.88 Charge your iPad, iPhone, or iPod on the go. PowerJolt Micro’s DC charger delivers 2.1 amps of power for fastest possible charging of your iPad, iPhone, or iPod. Charge from almost any vehicle’s 12 volt accessory socket with this low-profile, micro form-factor PowerJolt. Included dock cable can be used separately to charge or sync your iPad, iPhone, or iPod. To charge other devices, use the cable … |
Ebay listings for Power Factor products.
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250P AC/DC 208/230/460/575 60 Hertz 1Ph With Power Factor Correction 907015 $2,758.99 |
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EMS Energy Saver KVAR Power Factor Correction Unit Seminar Presentation Demo Kit $489.88 |
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Lincoln Electric Power Factor Correction Kit K1831-1 $303.99 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3300 $260.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3400 $260.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3200 $250.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3150 $240.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3100 $240.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3400 Flush Mount $200.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 3200 Flush Mount $200.00 |
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power saver 2401M kvar electric saver Power factor $135.20 |
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No Electrician Needed Power Factor Correction Unit / Installs in Miuntes $124.88 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 1200 FUSED $110.00 |
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ZALMAN ZM500-GS Active PFC Improved Power Factor Reduced Harmonics * Free EMS* $104.99 |
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Power Factor Optimizer Capacitor $99.95 |
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electric saver power saver 2401 kvar power factor $99.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 1200 $80.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 1300 $80.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 1100 $70.00 |
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POWER FACTOR SAVER AND ENERGY SAVINGS KVAR UNIT 1150 $70.00 |
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SOLA E420-F-134-TP HIGH POWER FACTOR BALLAST(1LOT OF 2) $16.99 |
Power System Resonance
Hot vibes can result when harmonics and capacitors get together
Is it possible to install “Power Factor Correction Capacitors” and have PF get worse? It certainly is, and a starting place to understanding this puzzle lies in the distinction between Displacement PF (DPF) and Total Power Factor (PF). The penalty for not understanding the difference can be blown capacitors and wasted investment. Total PF and Displacement PF are the same in one basic sense: they are the ratio of Real Power to Apparent Power, or Watts to VA. DPF is the classic concept of power factor. It can be considered as the power factor at the fundamental frequency. Total Power Factor, abbreviated to Power Factor (PF), now includes the effects of fundamental and of harmonic currents (it is also referred to as True PF or Distortion PF). It follows that with the presence of harmonics, PF is always lower than DPF and is also a more accurate description of total system efficiency than DPF alone.
Strictly speaking, the term “Power Factor” refers to Total PF, but in practice can also be used to refer to DPF. Needless to say, this introduces some confusion into discussions of power factor. You have to be clear which one you’re talking about.
Displacement Power Factor
Lower DPF is caused by motor loads which introduce the need for Reactive Power (Volt-Amp Reactive or VARs). The system has to have the capacity, measured in Volt-Amps (VA) to supply both VARs and Watts. The more VARs needed, the larger the VA requirement and the smaller the DPF. The cost of VARs is accounted for in a power factor penalty charge. Utilities often levy additional charges for DPF below a certain level; the actual number varies widely, but typical numbers are 0.90 to 0.95. To reduce VARs caused by motor loads, power factor correction capacitors are installed. Upstream system capacity, both in the plant and at the utility level, is released and available for other uses. Historically, this has been the gist of the PF story: a relatively well-known problem with a relatively straightforward solution.
Harmonics and Capacitors
Harmonics have had a dramatic impact on our approach to Power Factor correction. The motor and capacitor loads described above are all linear and for all practical purposes generate no harmonics. Non-linear loads such as ASDS, on the other hand, do generate harmonic currents. Take a plant which is step-by-step putting adjustable speed drives on its motor loads. ASDs generate significant harmonic currents (5th and 7th on six-pulse converter drives). Suddenly the fuses on existing PF correction caps start blowing. Since these are three-phase caps, only one of the three fuses might blow. Now you’ve got unbalanced currents, possibly unbalanced voltages. The electrician replaces the fuses. They blow again. He puts in larger fuses. Now the fuses survive, but the capacitor blows. He replaces the capacitor. Same thing happens. What’s going on? Harmonics are higher frequency currents. The higher the frequency, the lower the impedance of a cap. The cap acts like a sink for harmonic currents.
Power System Resonance
In a worst-case scenario, the inductive reactance (XL) of the transformer and the capacitive reactance (XC) of the PF correction cap form a parallel resonant circuit: XL= XC at a resonant frequency which is the same as or close to a harmonic frequency. The harmonic current generated by the load excites the circuit into oscillation. Currents then circulate within this circuit which are many times greater than the exciting current. This so-called “tank circuit” can severely damage equipment, and it will also cause a drop in power factor. Perversely, this resonant condition often appears only when the system is lightly loaded, because the damping effect of resistive loads is removed. In other words, we have what the audio buffs call a “high Q” circuit.
Imagine coming to work on a Monday and seeing the insulation on your cables melted off. How can this happen over a weekend when there was hardly any load on the system? Has Ohm’s Law been overruled? Not quite. Your power system just spent the weekend tanked out on the Harmonics. It was quite a party, but now comes the clean-up.
Start with Harmonics Mitigation
The correct solution path starts with measuring and mitigating the harmonics generated by the drives. (One useful tool for measuring harmonics and capacitance is the Fluke 43B Power Quality Analyzer.) Harmonic trap filters would generally be called for. These trap filters are installed locally on the line side of the drive. Their effect is very much like the traditional PF correction cap, in two senses: they reduce DPF as well as PF, and also they localize the circulation of the problem harmonics (generally the 5th). Harmonics mitigation and traditional DPF correction should be addressed as one systems issue. In other words, manage Total PF, not just DPF.
About the Author
A graduate of Oakland University (Rochester, MI), Steve Glad is a writer with Structured Information (http://www.strucinfo.com/) in Needham Heights, MA. He frequently writes about industrial technology topics.
Lecture – 15 Power Factor
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