What is the effect of back reactive power on the generator ?
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Active power is the power that does useful work. It's quite easy to understand and visualize.
However, We find the concept of Reactive power little bit confusing because reactive power does not contribute in doing useful work. From our childhood we are being taught that Power is tendency to do work. If it does not contribute in doing useful work then how can it be "Power"?
In case of purely resistive load like incandescent lamp, electrical energy is directly converted into useful work (light and heat energy in this particular case), no intermediate electric or magnetic field is required in between. And hence no any power is wasted in creating electrical or magnetic field. Therefore the total Power is entirely Active Power that does useful work and there's no any requirement of Reactive Power.
However in case of inductive loads like motors , electrical energy can't directly be converted into useful work (rotation of motor in this particular case). This is because , to convert electrical energy into rotational energy, magnetic field has to be created in between the gaps of stator and rotor of Motor. Hence, some amount of energy has to be used in creating magnetic field. The portion of power that contributes in creating magnetic field is known as Reactive Power . From view point of efficiency, reactive power may be seen as power loss because it's role is limited to creating magnetic field and does not contribute in driving load. .Nevertheless, reactive power isn't actually a loss because it creates magnetic field without which electrical energy in stator could not have been converted to rotational energy in rotor.
Let us try to understand the concept of Reactive Power by taking the simple example of aeroplane carrying crowd of passengers from place A to place B. The main purpose of flight is to carry the passengers from place A to place B. The fuel spent in carrying the total weight of all passengers combined is analogous to Active Power. This fuel does main work. However some amount of fuel is also spent in lifting the weight of aeroplane itself. This can't be avoided. Without lifting it's own weight , aeroplane can't transport passengers form place A to place B. This fuel (used in lifting its own weight) is analogous to Reactive Power.
Analogy between example of Motor and Aeroplane
Therefore, inductive loads like motor demand some amount of reactive power in order to create magnetic field. Larger is the volume of inductive load in Power system , larger will be the demand of reactive power.
50.3k Views · ·
Originally Answered: What is reactive power? What is its physical significance and how is reactive power compensation performed?
REACTIVE POWER ASSISTS THE FLOW OF ENERGY IN AC CIRCUITS.
Below is the explanation in layman's terms -
Consider there is a small river dividing two cities and you need to build bridge over it to connect both the cities. After building bridge, you also need to construct a house on the other side of the river.
For the whole work including bridge and house, you've got only 100 wooden planks of which 10 are used to create bridge over the river. The workers will use this bridge to cross the river and transport items and construct a house on the other side. Here the main work is to build the house on the other side for which we've created a bridge to move from one point to another. In this case, are the wooden planks used in constructing the bridge directly contributing to the building of house ? NO. We've used 10 wooden planks for bridge and that cannot be used for building the house.
And this - THE BRIDGE is what reactive power does.
100 wooden planks is the total complex power of which some amount is used to create bridge (10 planks) and remaining active power (90 planks) does the useful work. This is why we say reactive power does not do useful work.
In transmission lines, reactive power maintains the voltage level of the line so that active power can flow to do useful work and this is why we compensate reactive power by external means. It is very much neccessary for the line to operate, for active power to flow.
And for how it is done, a capacitor (to supply reactive power to increase voltage profile) or an inductor (to absorb reactive power to decrease voltage profile) is connected in parallel to transmission line.
Nowadays, power electronic compensators are used for automatic and varying degree of compensation.
Hope it helps.
44k Views ·
Originally Answered: How can capacitors improve power factor?
Mostly loads are inductive in nature. Inductive load causes currents to lag behind voltage due to which load forces to draw more current.
However, We find the concept of Reactive power little bit confusing because reactive power does not contribute in doing useful work. From our childhood we are being taught that Power is tendency to do work. If it does not contribute in doing useful work then how can it be "Power"?
In case of purely resistive load like incandescent lamp, electrical energy is directly converted into useful work (light and heat energy in this particular case), no intermediate electric or magnetic field is required in between. And hence no any power is wasted in creating electrical or magnetic field. Therefore the total Power is entirely Active Power that does useful work and there's no any requirement of Reactive Power.
However in case of inductive loads like motors , electrical energy can't directly be converted into useful work (rotation of motor in this particular case). This is because , to convert electrical energy into rotational energy, magnetic field has to be created in between the gaps of stator and rotor of Motor. Hence, some amount of energy has to be used in creating magnetic field. The portion of power that contributes in creating magnetic field is known as Reactive Power . From view point of efficiency, reactive power may be seen as power loss because it's role is limited to creating magnetic field and does not contribute in driving load. .Nevertheless, reactive power isn't actually a loss because it creates magnetic field without which electrical energy in stator could not have been converted to rotational energy in rotor.
Let us try to understand the concept of Reactive Power by taking the simple example of aeroplane carrying crowd of passengers from place A to place B. The main purpose of flight is to carry the passengers from place A to place B. The fuel spent in carrying the total weight of all passengers combined is analogous to Active Power. This fuel does main work. However some amount of fuel is also spent in lifting the weight of aeroplane itself. This can't be avoided. Without lifting it's own weight , aeroplane can't transport passengers form place A to place B. This fuel (used in lifting its own weight) is analogous to Reactive Power.
Analogy between example of Motor and Aeroplane
Therefore, inductive loads like motor demand some amount of reactive power in order to create magnetic field. Larger is the volume of inductive load in Power system , larger will be the demand of reactive power.
50.3k Views · ·
Originally Answered: What is reactive power? What is its physical significance and how is reactive power compensation performed?
REACTIVE POWER ASSISTS THE FLOW OF ENERGY IN AC CIRCUITS.
Below is the explanation in layman's terms -
Consider there is a small river dividing two cities and you need to build bridge over it to connect both the cities. After building bridge, you also need to construct a house on the other side of the river.
For the whole work including bridge and house, you've got only 100 wooden planks of which 10 are used to create bridge over the river. The workers will use this bridge to cross the river and transport items and construct a house on the other side. Here the main work is to build the house on the other side for which we've created a bridge to move from one point to another. In this case, are the wooden planks used in constructing the bridge directly contributing to the building of house ? NO. We've used 10 wooden planks for bridge and that cannot be used for building the house.
And this - THE BRIDGE is what reactive power does.
100 wooden planks is the total complex power of which some amount is used to create bridge (10 planks) and remaining active power (90 planks) does the useful work. This is why we say reactive power does not do useful work.
In transmission lines, reactive power maintains the voltage level of the line so that active power can flow to do useful work and this is why we compensate reactive power by external means. It is very much neccessary for the line to operate, for active power to flow.
And for how it is done, a capacitor (to supply reactive power to increase voltage profile) or an inductor (to absorb reactive power to decrease voltage profile) is connected in parallel to transmission line.
Nowadays, power electronic compensators are used for automatic and varying degree of compensation.
Hope it helps.
44k Views ·
Originally Answered: How can capacitors improve power factor?
Mostly loads are inductive in nature. Inductive load causes currents to lag behind voltage due to which load forces to draw more current.
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