# Electrical resistance and power factor

For example, the triplen, or zero-sequence, harmonics 3rd, 9th, 15th, etc. In a delta-wye transformerthese harmonics can result in circulating currents in the delta windings and result in greater resistive heating. In a wye-configuration of a transformer, triplen harmonics will not create these currents, but they will result in a non-zero current in the neutral wire. When expressed as a fraction, this ratio between true power and apparent power is called the power factor for this circuit. Because true power and apparent power form the adjacent and hypotenuse sides of a right triangle, respectively, the power factor ratio is also equal to the cosine of that phase angle.

Using values from the last example circuit: It should be noted that power factor, like all ratio measurements, is a unitless quantity.

## Power Factor Calculation

For the purely resistive circuit, the power factor is 1 perfectbecause the reactive power equals zero. Here, the power triangle would look like a horizontal line, because the opposite reactive power side would have zero length.

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

The same could be said for a purely capacitive circuit. If there are no dissipative resistive components in the circuit, then the true power must be equal to zero, making any power in the circuit purely reactive. The power triangle for a purely capacitive circuit would again be a vertical line pointing down instead of up as it was for the purely inductive circuit.

If our last example circuit had been purely resistive, we would have been able to deliver a full The poor power factor makes for an inefficient power delivery system. Inductive reactance can only be canceled by capacitive reactanceso we have to add a capacitor in parallel to our example circuit as the additional load.

Since we know that the uncorrected reactive power is Figure below Parallel capacitor corrects lagging power factor of inductive load. V2 and node numbers: The power factor for the circuit, overall, has been substantially improved.

The main current has been decreased from 1. The power factor is much closer to being 1: Since the impedance angle is still a positive number, we know that the circuit, overall, is still more inductive than it is capacitive.

## Power Factor | Calculation and Power Factor Improvement

If our power factor correction efforts had been perfectly on-target, we would have arrived at an impedance angle of exactly zero, or purely resistive. If we had added too large of a capacitor in parallel, we would have ended up with an impedance angle that was negative, indicating that the circuit was more capacitive than inductive. The SPICE circuit file has a zero volt voltage-source V2 in series with the capacitor so that the capacitor current may be measured. The start time of msec instead of 0 in the transient analysis statement allows the DC conditions to stabilize before collecting data.

The reference is Vtotal, to which all other measurements are compared. This is because the applied voltage, Vtotal, appears across the parallel branches of the circuit. There is no single current common to all components. We can compare those currents to Vtotal. Zero phase angle due to in-phase Vtotal and Itotal.

Note that the total current Itotal is in phase with the applied voltage Vtotalindicating a phase angle of near zero. This is no coincidence. Note that the lagging current, IL of the inductor would have caused the total current to have a lagging phase somewhere between Itotal and IL.

However, the leading capacitor current, IC, compensates for the lagging inductor current. The result is a total current phase-angle somewhere between the inductor and capacitor currents. Moreover, that total current Itotal was forced to be in-phase with the total applied voltage Vtotalby the calculation of an appropriate capacitor value.In electrical engineering, the power factor of an AC electrical power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit, and is a dimensionless number in the closed interval of −1 to 1.

## Power Factor (PF)

2 Technical Application Papers Power factor correction and harmonic filtering in electrical plants Introduction Introduction In electrical plants the loads draw from the network elec-. First let me say that your article on power factor is the best I have found. Second, I am an electrical engineer - electronics not power - but I do remember power factor calculations from . noun. the act or power of resisting, opposing, or withstanding.

the opposition offered by one thing, force, etc., to another. Electricity.. Also called ohmic resistance. a property of a conductor by virtue of which the passage of current is opposed, causing electric energy to be transformed into heat: equal to the voltage across the conductor divided by the current flowing in the conductor.

Power Factor is the ratio of the real power of a load to the apparent power; a measure of the degree to which the voltage waveform and the current waveform are . For your business and technology editors Power Factor improved by Variable Speed AC Drives By Mauri Peltola, ABB Oy, Drives The use of AC induction motors is essential for industry and utilities.

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