*How to find out of Apparent Power, True Power, Reactive Power and Power factor?*

*The product of rms values of current and voltage, VI is called the Apparent power and is measured in Volt-amperes or kilovolt Ampere (KVA).*

*The true power in an AC Circuit is obtained by multiplying the Apparent power by the power factor and is expressed in Watts or kilowatts (KW).*

*The product of apparent power, VI and the sine of the angle between voltage and current, sinÎ¦ is called the Reactive Power. This is also known as wattless power and is expressed in reactive Volt-amperes or kilovolt Amperes ( kvar).*

*i.e., Apparent power,*

* VI*

*S = VI Volt-amperes or --------- kVA*

* 1000*

*True power, P = VI COS ***Î¦ watts or **

** V I Cos****Î¦**

** ------------------ KW**

** 1000**

**Reactive Power, Q = V I Sin****Î¦ VAR or**

** V I Sin****Î¦**

** ---------------- KVAR**

** 1000 **

**And KVA = √ ( kw)^2 + (kvar) ^2**

**Power factor may be defined as **

**I) Cosine of the phase angel between voltage and current **

**Or **

**II) the ratio of the resistance to impedance or **

**III) the ratio of true power to apparent power.**

**The power factor can be greater than unity. The power factor is expressed eighter as fraction or as a percentage. It is usual practice to attach the word "lagging" or "leading" with the numerical value or power factor to signify whether the current lags behind or leads the voltage.**

**1) Active Component of current.**

**The Current component which is in phase with Circuit voltage**

**( i.e., ICos****Î¦) and contributes to active or true power of the Circuit is called the Active ( wattful or in phase ) component of current.**

**2) Reactive component of current.**

**The Current component which is in quadrature ( or 90° out of phase ) to Circuit voltage ( i.e., I sin****Î¦ ) and contributes to Reactive Power of the Circuit, is called the Reactive ( or wattless ) component of current.**

__Q- Factor of Coil.__

**Reciprocal of power factor is known as **

**Q-factor of the coil. It is also called the quality factor to figure of merit of a coil.**

**Mathematically Q - factor**

** 1 1 Z**

** = ------------------------ = ------------- = ------**

** Power factor Cos****Î¦ R**

**If R is very small in comparison to **

**Inductive reactance XL , the **

** XL 2Ï€fL**

**Q- factor = ---------- = --------**

** R R**

** Maximum Energy stored**

**Also Q = 2Ï€× ------------------------------------**

** Energy dissipated per cycle**

** **

## 0 Comments