differnce between real and reactive power

kaniranjith · 2010-08-18T17:35:25+00:00

hi am a 2nd yr electrical student and i want to know wats real power and reactive power.... 😀

differnce between real and reactive power

kaniranjith

Member

Updated: Oct 26, 2024

Views: 1.1K

hi am a 2nd yr electrical student and i want to know wats real power and reactive power.... 😀

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sushant005

Member • Aug 19, 2010

We know the general meaning of an Electric power is the product of voltage(DC) and current(DC).
And the current and voltage in AC Circuits are complex in nature and their product result in a complex power.
Thus the expression of a complex is given by,
S=P+jQ and P-jQ
where,
S is called as the Apparent power
P is called as the real or active power and
Q is called as the Reactive or imaginary power.

And
if Q is -ve then the circuit is Capacitive.
If Q is +ve then the circuit is Inductive.
if Q is Zero then the circuit is Resistive.

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kaniranjith

Member • Aug 19, 2010

thk u 4 ur reply😁but i want to know wat a real and reactive power actually does in a circuit..

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sushant005

Member • Aug 19, 2010

If we consider the power factor it is defined as the ration of Active Power to the Apparent power and power factor should have the value close to the unity.
Question must be asked why its should be close to unity?
Answer is, in order to result higher active power from a given apparent power.And power factor is unity for resistive load and it becomes less when the reactive power gets involved in the circuit and which results in the power factor lagging.

our most of the loads in the power system are inductive in nature such as fans,tube lights,refrigerator,AC etc..
So maintain the unity power factor we have to connect additional capacitors so as to neutralize the lagging effect in the circuit.the most effective methods for the power factor improvement is reactive power compensation by using the desired type.

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Eng.Electronic

Member • Aug 20, 2010

Real power is active powe whichis used to do work or to produce energy & it is V*A*Cos phi whreas reactive power is the power which is used to magnetise the magnetic field in electrical motors,transformers,electrical ballasts etc..and it is V*A*sin phi

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kaniranjith

Member • Aug 20, 2010

thk u 😁i really got an idea..

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aj_onduty

Member • Aug 25, 2010

This is just for an information. Its the practical side of all the things we read in the books.
If we percieve things through the point of view of the electrical energy sellers(Electricity boards, private power supply, etc), if a load connected is inductive, it draws more reactive power from the system. To balance it, we have to increase the excitation of the generator. This increases the cost of production of each unit of energy. Also this increase in use in reactive power consumption is not recorded in the energymeter. So, overall, there is loss to the generating station(ultimately). this is the case during peak time. In many countries, peak time consumption is charged extra.
So, if we have a unit power factor, we can produce and distribute electricity at the least rate.

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swapnakumar

Member • Aug 25, 2010

kaniranjith
hi am a 2nd yr electrical student and i want to know wats real power and reactive power.... 😀
real power is obtained when the circuit is purely resistive in nature on the other hand reactive power comes into picture when you have capacitor and inductor,this is also called apparent power because of the presence of imaginary quantity j

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