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Watts = Current x Voltage x Power Factor In an AC circuit both the voltage and current are sine waves. When they are in phase (waveforms lie over top of one another) the PF is one. As they become out of phase the PF decreases to zero. This happens when the phase difference is 180 degrees. In this case the positive peak of current is at the same place in time as the negative peak of voltage or vice versa. So when PF is zero you coul say you are getting zero watts.

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An a.c. load current can be resolved into two components. One, in phase with the supply voltage, and responsible for supplying true power to the load. The other, at right angles to the supply voltage, and responsible for supplying reactive power (e.g. the magnetic field, in the case of a motor). As reactive power is sometimes termed 'wattless power', we can say that the second component of this current is 'wattless current'.

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Q: What do you mean by wattless current and power factor in AC?
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What is the difference between displacement and true power factor?

'Displacement power factor' is the technically-correct term used to describe the cosine of the phase angle (i.e. the angle by which the load current leads or lags the supply voltage) due to the reactance of a load. Usually, when we talk about the 'power factor' of a load, we mean 'displacement power factor'.However, another type of power factor can exist in a circuit, due to the presence of harmonics in the current waveform, due to non-linear loads such as SCR rectifiers. This type of power factor is temed 'distortion power factor', and may be corrected using filters.So, the terms 'displacement' and 'distortion' are used whenever it is necessary to clarify these different types of power factor.


What is the difference between unity power factor to 8 power factor?

Power factor does not go above 1. It is the cosine of the phase angle between voltage and current and, as such, can range between +1 and -1, although it should be understood that a negative power factor is mathematically equivalent to a generator - when looking at the load as if it is a motor - or vice versa. Unity power factor is applicable for a resistive load. A typical power factor for a big motor is about 0.92. A theoretical power factor of zero, corresponding to a phase angle of 90 degrees, would mean that the load is purely inductive or capacitive, and that the power supply and conductors are also ideal or theoretical.


What are the adverse effects of poor power factor?

Low power factor means higher than necessary load currents. These require unnecessary expenditure on the amount of copper in supply equipment such as cables, transformers, and switchgear. Higher than necessary load currents also mean greater voltage drops and poorer voltage regulation.


Which power factor is advantage lagging or leading and why?

A lagging power factor is caused by inductive reactance, which is composed of resistance and inductance -- and the resistance component lowers the supply volts. A leading power factor provides capacitive reactance that actually helps improve source voltage -- this helps motor loads run cooler.


How do you calculate actual power factor?

The power factor of a circuit is defined as the cosine of the phase angle -which is the angle by which the supply current lags or leads the supply voltage in AC circuits.Power factor is always expressed as either a 'lagging power factor' or as a 'leading power factor'.The terms 'lagging' or 'leading' describe the relationship of the supply current to the supply voltage. Since current lags voltage in an inductive circuit, 'lagging power factors' describe inductive circuits; since current leads voltage in capacitive circuits, 'leading power factors' describe capacitive circuits. In practice, lagging power factors are more common than leading power factors, because most practical loads are inductive (e.g. motors, etc.).Power factors are normally expressed as a decimal (e.g. '0.8 lagging') although, in the past they were often expressed as a percentage (e.g. '80% lagging'). 'High' power factors tend towards unity, whereas 'low' power factors tend towards zero.In terms of power, the cosine of a circuit's phase angle and, therefore, its power factor is the ratio of that circuit's true power (expressed in watts) and its apparent power (expressed in volt amperes).Power factor has no effect whatsoever upon the energy consumed by a load, but it does effect the amount of current drawn from the supply. 'Low' power factors result in unnecessarily-large load currents for any given load, which mean that the supply utilities need to use larger than necessary conductor sizes (expensive!). For industrial or commercial (but not residential) loads, therefore, it is often desirable to 'improve' the load's power factor towards unity, which acts to reduce the load current. This is most-usually done by installing capacitors close to the load, and is termed 'power-factor correction' or 'power-factor improvement'. Capacitors used in this way are rated in reactive volt amperes, rather than in microfarads.

Related questions

What does power factor mean in math?

power factor is the cosine of the angular difference between current and voltage and must be taken into account to get true power (watts)


What does it mean to have a power factor of 1?

First we need to know what is power factor ? it's cosine of angle between the current and voltage at that point where we wish to measure it. so power factor of "1" means the angle between the voltage and current is 0 degree. It means literally that the current and voltage is in the same phase.


What does watless mean?

The spelling closest to this word is wattless [two t's]. A wattmeter is an instrument for measuring electric energy and if there is none then it would be wattless. Wattles [with one s] are acacia trees indigenous to Australia.


What does zero leading power factor mean?

A 'leading' power factor indicates that the load current is leading the supply voltage. Since power factor is the cosine of the angle by which the load current either leads or lags the supply voltage (i.e. the load's phase angle), a cosine of 0 corresponds to a phase angle of 90 degrees. So, a power factor of 0 (leading) indicates that the load current is leading the supply voltage by 90 degrees, which means that the load must be purely capacitive.


What is the difference between displacement and true power factor?

'Displacement power factor' is the technically-correct term used to describe the cosine of the phase angle (i.e. the angle by which the load current leads or lags the supply voltage) due to the reactance of a load. Usually, when we talk about the 'power factor' of a load, we mean 'displacement power factor'.However, another type of power factor can exist in a circuit, due to the presence of harmonics in the current waveform, due to non-linear loads such as SCR rectifiers. This type of power factor is temed 'distortion power factor', and may be corrected using filters.So, the terms 'displacement' and 'distortion' are used whenever it is necessary to clarify these different types of power factor.


Is pure inductor consumes energy?

Pure inductors consume and produce power, just like other reactive devices. The difference is that the current is not in phase with the voltage, resulting in the waveform of the power being oscillating about zero, with a net mean power of zero. In this "pure" case, the power factor is zero, but that does not mean there is no power - its just that the power "reading" is unsophisticated and not compensating for power factor.


What mean power factor 0.26 lead?

When looking at power factor, it is the ratio of watts (true power) to VA. The power factor is how we measure power systems. A person with a low power factor like .26 will have a higher electricity bill.


How does a power factor correction will help to the normal user which his load power factor is already 0.9?

Correcting a power factor of 0.9 would reduce the current by only 10%, so it may not be worth it except for a very high-power load.Additional AnswerIf, by 'normal user', you mean a residential consumer, then power factor plays no part whatsoever in the calculation of his energy bill. Energy meters monitor the supply voltage and the in-phase (resistive) component of the consumer's load current (together with the time), so it completely ignores power factor. Therefore, power factor correction, whether high or low, will make absolutely no difference to residential consumers. Companies that sell capacitors to improve residential power factor are scam artists!Power-factor improvement ONLY applies to industrial consumers.


How do you convert kav to kilowatt?

By "kav", I'm assuming you mean "thousand-ampere-volts" ... usually represented as "KVA". Watts = (Volts) x (Amperes) x (power factor on the line) KW = KVA x (power factor on the line). The power factor on the line is the cosine of the phase difference between the voltage and current waveforms on the line.


What is the difference between unity power factor to 8 power factor?

Power factor does not go above 1. It is the cosine of the phase angle between voltage and current and, as such, can range between +1 and -1, although it should be understood that a negative power factor is mathematically equivalent to a generator - when looking at the load as if it is a motor - or vice versa. Unity power factor is applicable for a resistive load. A typical power factor for a big motor is about 0.92. A theoretical power factor of zero, corresponding to a phase angle of 90 degrees, would mean that the load is purely inductive or capacitive, and that the power supply and conductors are also ideal or theoretical.


What is crest factor of online ups?

Crest factor is the ratio between the instantaneous peak current required by the load and the RMS current (RMS stands for Root Mean Square, which is a type of average). Most common electrical appliances exhibit a crest factor of 1.4 (1.4 is the ratio of the peak value of a sine wave to its RMS value). Computers and IT equipment with Power Factor Corrected power supplies exhibit a crest factor of 1.4. Personal computers and stackable hubs exhibit a crest factor of 2 to 3.


What does unity power factor UPF mean?

Unity power factor has a value of 1.0. This means the current and voltage waveforms are in phase. This is only possible if the net load is non-reactive (resistive). If the load is either capacitively or inductively reactive, the power factor will be other than unity. If an inductively reactive load such as a motor is offset by a capacitively reactive load such as a PF correction capacitor, it is possible to acheive a net load that has unity power factor. Some loads, such as resistance heaters, are intrinsically non-reactive, and present a unity power factor.