Importance and corrections of Power Factor


Power Factor

Power factor is that the ratio between the KW and also the KVA drawn by an electrical load where the KW is that the actual load power and therefore the KVA is that the apparent load power. it's a measure of how effectively the present is being converted into useful work output and more particularly could be a good indicator of the effect of the load current on the efficiency of the provision system.

Power Factor Formula
  • All current flow causes losses both within the supply and distribution system. A load with an influence factor of 1.0 leads to the foremost efficient loading of the availability. A load with an influence factor of, say, 0.8, leads to much higher losses within the supply system and the next bill for the buyer. A small improvement in the power factor can reduce its losses. Because the loss is proportional to the square of the current.
  • A convenience factor is the small amount of time a missing power is considered. So it is considered as reactive power. Which is unfortunately sufficient to supply the magnetic field required by motors and other inductive loads to perform its desired functions. Reactive power is interpreted as Vottles. Hence magnetized or wasted power and it guides the power supply system and an additional burden on the consumer's bill.
  • A poor power factor is sometimes the results of a major phase difference between the voltage and current at the load terminals, or it may be thanks to a high harmonic content or a distorted current waveform.
  • A poor power factor is usually the results of an inductive load like an induction motor, an influence transformer, and ballast in a very luminary, a welding set or an induction furnace. A distorted current waveform consists of a rectifier, a variable speed drive, a switch mode power supply resulting in light.
  • A poor power factor because of inductive loads may be improved by the addition of power factor correction equipment, but a poor power factor thanks to a distorted current waveform requires a change in equipment Design or the addition of harmonic filters.
  • Some inverters are quoted as having an influence factor of higher than 0.95 when, in reality, actuality power factor is between 0.5 and 0.75. The figure of 0.95 is predicated on the cosine of the angle between the voltage and current but doesn't take under consideration that the present waveform is discontinuous and so contributes to increased losses.
  • An inductive load requires a force field to work and in creating such a magnetic flux causes this to be out of phase with the voltage (the current lags the voltage). Power factor correction is that the process of compensating for the lagging current by creating a number one current by connecting capacitors to the availability.

P.F (Cos Ǿ)= K.W / KVA Or

P.F (Cos Ǿ)= True Power / Apparent Power.

KW is functioning Power (also called Actual Power or Active Power or Real Power).

It is the ability that really powers the equipment and performs useful work.

KVAR is Reactive Power.

It is the facility that magnetic equipment (transformer, motor and relay)needs to provide the magnetizing flux.

KVA is clear Power.

This is the vector sum of KVa and KW.

Displacement Power Factor Correction

An induction motor draws current from the provision that's made from resistive components and inductive components. The resistive components are:

  1. Load current.
  2. Loss current.
  3. Leakage reactance.
  4. Magnetizing current.
  • The current to the leakage reactance relies on the full current drawn by the motor, but the magnetizing current is independent of the load on the motor. The magnetizing current shall be between 20 and 60 percent of the rated full load current of the motor. The magnetizing current is that the current that establishes the flux within the iron and is incredibly necessary if the motor goes to control.
  • The magnetizing current doesn't actually contribute to the particular work output of the motor. it's the catalyst that enables the motor to figure properly. Magnetizing current and leakage reaction is considered as the passenger component of current. Which does not affect the capacity drawn by the motor. But provides the ability to spread within the supply and distribution system.
  • Take for example a motor with a current draw of 100 Amps and an influence factor of 0.75 The resistive component of this is 75 Amps and this can be what the KWh meter measures. the upper current will lead to a rise within the distribution losses of (100 x 100) /(75 x 75) = 1.777 or a 78% increase within the supply losses.
  • Power factor correction is added to neutralize some magnetization of the motor to minimize losses within the distribution system. The correct power factor is going to be 0.92 A 0.95 power factor correction is achieved by connecting the capacitor in parallel to the connected motor circuit and can be applied to the starter, or to the switchboard or distribution panel. The resulting capacitive current is leading and is employed to cancel the lagging inductive current flowing out of availability.

Power Factor Values

For the purely resistive circuit, the ability factor is 1 (perfect), because the reactive power equals zero. Here, the ability triangle would seem like a horizontal line, because the other (reactive power) side would have zero length.

For the purely inductive circuit, the facility factor is zero, because true power equals zero. Here, the ability triangle would seem like a vertical line, because the adjacent (true power) side would have zero length.

Power Factor Meter

The same may well be said for a purely capacitive circuit. If there aren't any dissipative (resistive) components within the circuit, then actuality power must be up to zero, making any power within the circuit purely reactive.

The power triangle for a purely capacitive circuit would again be a vertical line (pointing down rather than up because it was for the purely inductive circuit).

Importance of Power Factor

Power factor will be a crucial aspect to think about in an AC circuit due to any power factor but 1 implies that the circuit’s wiring should carry more current than what would be necessary with zero reactance within the circuit to deliver the identical amount of (true) power to the resistive load.

If our last example circuit had been purely resistive, we'd are ready to deliver a full 169.256 watts to the load with the identical 1.410 amps of current, instead of the mere 119.365 watts that it's presently dissipating thereupon same current quantity.

The poor power factor makes for an inefficient power delivery system.

Poor Power Factor

Poor power factor is corrected, paradoxically, by adding another load to the circuit drawing an equal and opposite amount of reactive power, to eliminate the consequences of the load’s inductive reactance.

Inductive reactance can only be canceled by capacitive reactance, so we've to feature a capacitor in parallel to our example circuit because the additional load.

The effect of those two opposing reactances in parallel is to bring the circuit’s total impedance adequate its total resistance (to make the impedance phase equal, or a minimum of closer, to zero).

Since we all know that the (uncorrected) reactive power is 119.998 VAR (inductive), we'd like to calculate the proper capacitor size to provide the identical quantity of (capacitive) reactive power.


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