Question

What will be the power factor of
alternating circuit containing
i) pure resistor
ii)
pure inductor ?​

Answer 1

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pure resistor.

Answer 2

Answer:

The power factor of pure resistive circuit is always unity i.e. 1.

In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher current increases the energy lost in the distribution system {apparently in Electrical Panels and Switchgears} and requires larger wires and other equipment dropped more energy. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor.

There are methods to improve the power factor. Power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the real power (watts). This increases generation and transmission costs. For example, if the load power factor were as low as 0.7, the apparent power would be 1.4 times the real power used by the load. Line current in the circuit would also be 1.4 times the current required at 1.0 power factor, so the losses in the circuit would be doubled (since they are proportional to the square of the current). Alternatively all components of the system such as generators, conductors, transformers, and switchgear would be increased in size (and cost) to carry the extra current.

Utilities typically charge additional costs to commercial customers who have a power factor below some limit, which is typically 0.9 to 0.95. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission.

With the rising cost of energy and concerns over the efficient delivery of power, active PFC has become more common in consumer electronics.

call for a power factor of ≥ 0.9 at 100% of rated output in the PC's power supply. According to a white paper authored by Intel and the U.S. Environmental Protection Agency. PCs with internal power supplies will require the use of active power factor correction to meet the ENERGY STAR 5.0 Program Requirements for Computers.

In Europe, it requires power factor correction be incorporated into consumer products.

When households are not charged for the reactive power they consume there is almost no monetary incentive for them to install power factor correction equipment. This is generally the case today, as household electric meters do not measure apparent power but only real power. Adding power factor correction merely affects the reactive power supplied or drawn and not real power, so utility costs are unaffected. However if there are high-resistance lines connected between the utility meter and a relatively high load then the power as measured by the meter can be reduced by a small amount with power factor correction. Any such savings are usually insignificant.