Power factor ac theory tutorial pdf

Electrical theory the answer lies within basic electrical theory. Power factor is the ratio of working power to apparent power. In the given circuit, calculate current i, the conductance g and the power p. It can be calculated by calculating the ratio of active power and apparent power. All dc based plugged in appliances and rechargeable battery based devices technically run on alternating current as they all use some form of dc power derived from ac for either charging of their batteries or powering of the system. May 05, 2000 however, once an explanation is given and you are aware of the correlation between the two, it should help give you a better overall understanding of power factor. Power triangle and power factor electrical power consumed in an ac circuit can be represented by the three sides of a right angled triangle, known commonly as a power triangle we saw in our tutorial about electrical power that ac circuits which contain resistance and capacitance or resistance and inductance, or both, also contain real power and. It is defined as the ratio of active or actual power used in the circuit measured in watts or kilowatts w or. First, lets look at the power generation pointofview. If both are sinusoidal but not in phase, the power factor is the cosine of the phase angle. Alternating current is when current flows in one direction for a set time, then changes direction, then changes back, and so on in a repeating cycle.

Generators, dc motors, ac theory, ac power, ac generators, voltage regulators, ac. Amidst these trends, power factor correction pfc or harmonic reduction requirements as. With the development of power semiconductor technology, the power handling capabilities and. Looking at our beer mug analogy above, power factor would be the ratio of beer kw to beer plus foam kva. 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. It is a measure of how effectively the current is being converted into useful work output and more particularly is a good indicator of the effect of the. It has 3 terminals mt1,mt2 and gate g its use is control of power in ac. The theory presented in the manual is then verified by performing various. Wayne beaty third edition mcgrawhill new york san francisco washington, d. Power electronics signifies the word power electronics and control or we can say the electronic that deal with power equipment for power control. For the simple and easy understanding,power factor is the alternating current ac value of electrical efficiency. Define power factor as it relates to true power and apparent power.

Ii alternating current ac with direct current covered and understood it is now time to delve into the world of alternating current. Scr power theory scr power theory training manual training. Introduction the majority of electronics designers do not worry about power factor pf. Where bulk power factor correction is installed, other loads can in theory be connected anywhere on the network. As we know that in an alternating current circuit, both electromotive force and current change continuously with respect to time. Lecture notes on power electronics veer surendra sai. For a dc circuit the power is pvi, and this relationship also holds for the instantaneous power in an ac circuit. Basics of understanding power factor and power factor. However, a bonus could be credited if the power factor were raised to 96%.

Lessons in electric circuits, volume ii ac ibiblio. Disadvantages of low power factor in ac circuit in ac circuits power factor plays an important role in the power system. Power of alternating current ac circuit and power factor. Pf is something that you learnt one day at school in your electrotechnics course as being the cos. Ac waveform and ac circuit theory ac sinusoidal waveforms are created by rotating a coil within a magnetic field and alternating voltages and currents form the basis of ac theory direct current or d. Auckland bogota caracas lisbon london madrid mexico city milan. This is the main reason why we cannot calculate the power for the same, as power is equal to the product of voltage and time. Circuits for power factor correction with regards to mains filtering. Nov 07, 2016 in qualitative terms, power factor is a measure of the congruency of voltage and current ac waveforms imposed by a load on the power mains. Thus, our example circuit started out with a power factor of 0. We hope to give you an easy explanation of what power factor is, and to answer. Effective august 2014 sa02607001e passive harmonic filters. The ratio of true power flow into load of apparent power. Calculating power factor power factor electronics textbook.

Power factor in electrical energy management course content what is power factor. Power electronics refers to an interdisciplinary subject within electrical engineering that deals with the design, control and conversion of power in its electric form. This is not a lecture, but rather a quick summary of the lecture on power factor correction for my students who have a midterm in a few days, as. Thus alternating current is the form via which power is delivered at the mains. Main power source ref signal circuit power electronics based on the switching of power semiconductor devices. The form factor of an ac waveform is the ratio of its rms value divided by its. One other quantity associated with an alternating current that we need to look at is the form factor. A power factor of less than one indicates the voltage and current are not in phase, reducing.

Circuits for power factor correction with regards to mains. If equipment or machine running in maximum efficiency,we can save the electric cost and keep the long life. Ac circuits basics, impedance, resonant frequency, rl rc rlc. As stated, we already know to desire a high power factor. In elementary courses in electricity, this is sometimes taught as the definition of power factor, but it applies only in the special case, where both the current and voltage are pure sine waves. Feb 28, 2017 this physics video tutorial explains the basics of ac circuits. Tutorial about the power triangle that is used to graphically represent the three power elements within an ac circuit,active, reactive and apparent power. A system that converts electric energy to an electric load through a control circuit is known as a power electronic system. Power factor is the relation between the kw and the kva drawn by an electrical load where the kw is the actual load power and the kva is the apparent load power. Power factor correction can make our electrical system more efficient. In particular, if a coil rotates in the presence of a magnetic field, the induced emf varies sinusoidally with time and leads to an alternating current ac, and provides a source of ac.

Power factor is the percentage of electricity that is being used to do useful work. Power factor correction in electric power systems youtube. The form factor is a parameter used in describing ac waveforms and is giving by the ratio between the rms value of the alternating quantity and the average value. Rms and average values, form factors, steady state. When ac theory is introduced, and especially when there is a bias towards radio frequencies, the very first new idea required by many people at least is a correct understanding of the word electricity. In this case the real power is equal to the apparent power thus making the system efficient. Ac circuits basics, impedance, resonant frequency, rl rc rlc lc circuit explained, physics problems. It is the cosine of the phase angle between the voltage waveform and the current waveform assuming sinusoidal waveforms. A power factor corrector is basically a ac to dc converter, and is usually based on an smps structure. Understanding power factor and how it affects your. Power factor is a calculation of available power versus consumed power.

Suppose a circuit draws a current of 10 a at a voltage of 200 v and its p. The basic functional blocks of a power factor corrector are shown in figure 1. If the power factor is higher than 95%, the demand will be decreased 1% for each 1% that the power factor is above 90%. Defining power factor power factor pf is the ratio of real power p flowing to the load, to the apparent power in the circuit s. However, the average power in an ac circuit expressed in terms of the rms voltage and current is. May 17, 2018 power factor is defined as the cosine of angle between the voltage phasor and current phasor in an ac circuit. Scroll to the bottom to watch the free youtube tutorial. Understanding power factor definitions kva, kvar, kw, apparent power vs. Some inverters are quoted as having a power factor of better than 0.

The limited scope of this lesson on alternating current does not permit full. Basics, maintenance, and diagnostics vii contents continued page 4. Understanding power factor and how it affects your electric bill. The poor power factor in an ac circuit may be corrected, or reestablished at a value close to 1, by adding a parallel reactance opposite the effect of the loads reactance. In most power application, base is the input terminal. To raise an 87% power factor to 96%, refer to table 6. Power bjt power bjt means a large voltage blocking in the off state and high current carrying capability in the on state. Power factor is a unitless number used in alternating current circuits, it can be used to refer to a single piece of equipment such as an induction motor or for the electricity consumption of an entire building. Whenever the current in a circuit alternates, so will the voltage, and an alternating voltage will of.

Ac, and although the meaning of ac, is alternating current a current that alternates its direction of flow around a circuit ac is often used in other terms such as ac signal and even ac voltage. Well learn what is power factor, what is good and bad power factor, how to compare power factor, the causes of power factor, why and how to fix power factor as well as some example calculations to help you learn electrical engineering. Power factor correction in ac system electrical axis. A standard smps uses pulse width modulation pwm to adjust the amount of power it supplies to the attached equipment. True power calculations measurements power factor correction capacitors system impacts i2 r losses, chapter 9 nec equipment sizing power factor charges problems with adding caps harmonic resonance volt rise power factor vs load factor. Practical implementation of fundamental theory concepts. Sometimes, however, our electrical distribution has a power factor much less than. Power triangle and power factor electrical power consumed in an ac circuit can be represented by the three sides of a right angled triangle, known commonly as a power triangle we saw in our tutorial about electrical power that ac circuits which contain resistance and capacitance or resistance and inductance, or both, also contain real power and reactive power. Sometimes the occurrence of the low power factor situation happened only during full blast operation of the plant. Usually the word lagging or leading is attached with the numerical value of power factor signifying whether the current lags behind or leads the voltage. The teaching of basic science often involves what are known as lies to children, and. Ignoring the relative phase of the two waveforms, the apparent power s is the simple product of the waveform amplitudes, s v. Sep 26, 2016 power factor is a dynamic value between 0 and 1 which depends on the operating conditions of the ac circuit.