**Understanding Reactive Power: A Deeper Dive**

In this video, we explore the concept of reactive power and how it relates to our everyday lives. You may be wondering what reactive power is and why it's a concern for power grids around the world.

The answer lies in the fact that many devices, such as motors and power supplies, draw not only true power but also reactive power. The current drawn by these devices can feature an inductive phase shift, which means the current waveform does not follow the same pattern as the voltage waveform. This phase shift is a result of the device's inductive nature.

To put it simply, when we connect a motor to a sinusoidal AC voltage, it creates a phase shift in the current waveform. This phase shift is what gives motors their notorious reputation for being energy hogs. But here's the thing: this phase shift also means that the calculated power waveform alternates between a load and generator function.

**The Role of Capacitors**

Now, you might be wondering how we can decrease the reactive power drawn by these devices. The answer is simple: use a capacitor! By connecting a capacitor to a sinusoidal AC voltage, we create a phase shift in the current waveform as well. However, this time, the current is leading with an angle of 90 degrees.

This means that the calculated power waveform also alternates between a load and generator function, which theoretically results in no true power being drawn from the capacitor due to its electrostatic fields. Since we know that inductors and capacitors basically oppose each other, we can use a capacitor to cancel out the inductive reactive power.

**Calculating Capacitor Values**

To calculate the value of the capacitor needed to cancel out the inductive reactive power, we need to do some math. Using the values from our motor example, we find that we would need a 0.18 microfarad capacitor to cancel out the inductive reactive power. However, since such capacitors are not readily available, we can use multiple smaller capacitors in parallel to achieve the same effect.

**Understanding Power Factor Correction (PFC)**

Now, you might be wondering how PFC works and why it's necessary for modern power supplies. The answer lies in the fact that many devices, including laptop power supplies, draw a significant amount of reactive power even though their current waveform does not feature a phase shift.

The problem with these devices is that the current waveform is no longer sinusoidal, which results in higher harmonics being drawn from the power grid. To mitigate this issue, we can use PFC to ensure that the current waveform is sinusoidal and that only true power is drawn from the power grid.

**Conclusion**

In conclusion, reactive power is an important concept to understand when it comes to power grids and devices. By using capacitors and understanding the principles of PFC, we can reduce the amount of reactive power drawn by these devices and ensure a more efficient use of energy.

The complex plane representation of true power (P), reactive power (Q), and apparent power (S) is a useful tool for visualizing how these concepts relate to each other. The power factor, which describes the relation between true power and apparent power, is also an important concept to understand.

As we continue to explore the world of electricity and energy efficiency, it's essential that we have a solid understanding of these fundamental principles.

WEBVTTKind: captionsLanguage: enI recently bought myself a new multimeter as an early Christmas gift but this is no ordinary multimeter it is an energy multimeter which means by connecting its three probes to suitable main socket adapter we can measure the electric power and also energy overtime of all hooked up AC appliances and while measuring the power draw of a few circuits I noticed that most of them feature a rather low power factor and thus draw comparatively much reactive power which is not desirable but what actually is the power factor or reactive power to begin with well stay tuned because in this electronic basics episode I will tell you all about this negative side effect of power electronics in what consequences it can have for our power grids let's get started let's start with a classical example for reactive power the transformer when I hooked up my first transformer to the power grids I was shocked to find out that I drew quite a lot of current on the inputs without even featuring a power drawing load on the outputs this example features a voltage of 228 volts and the current of 24 millions on the inputs which would equal a power of around 5.5 Watts that would get turned into heats that would be quite inefficient but while I was touching the transformer I realized that it was not getting as hot as the power draw would like you suspects the reason is that I measured the apparent power whose units is both unpaired which is quite literally how you calculated as well this apparent power consists of true power which for example heats up a resistor or moves an electric motor and reactive power which is almost not useful for anything to better understand it let's have a look at the mains voltage and more importantly the current the transformer drawers now please ignore the weird v-shape the transformer creates whose reason are the magnetic properties of its and instead let's focus on the paste shift between voltage and current as you can see the current is lagging with a phase shift of around 80 degrees the reason is that the transformer builds up a complex impedance consisting of a resistor and inductor but feel free to watch my previous basics video about the subject to learn more about that to make this example simpler though let's decrease the resistance of the impedance to almost zero and thus replace the transformer with an inductor by hooking it up to a suitable sinusoidal AC voltage and connecting the measurement equipments we can see how its current is a decent-looking sine wave with a phase shift of 90 degrees now I already told you that apparent power is calculated by voltage multiplied by current which I can do on the oscilloscope through the math function as you can see the resulting power waveform changes its polarity you will double the frequency and the areas underneath the waveform to zero are about the same size that means in the positive areas the inductor acts as loads by consuming power and in the negative areas the inductor acts as a generator by supplying power and since the areas are about the same the average power draw of the inductor is basically zero so no true power is being used all the inductor does is oscillating power between itself and the power source through its electromagnetic fields and this power is known as reactive power with the units volt-ampere reactive at this point you might be asking yourself if this power simply creates an oscillation and does not really waste power why should I care about it well the reason is that current does flow nevertheless which means our wires not only need to be able to handle the true currents but also the reactive current which means they need to be thicker and since the wire also features a small resistance as well as a few other components even reactive currents does create a small power loss by the way if we would look at the power curve of a traditional resistor we would see that the power would only be positive due to the same polarity of the current and voltage which means the resistor always acts as loads but anyway now we know that our transformer draws reactive power due to its inductance how can we fix it since the transformer is a rather complex electrical components all we have to do is to attach a load to its secondary sites and in acts more like a resistive loads that only draws a very small amount of reactive power so that is a bad example let's rather focus on the small synchronous motor I cut from a microwave by directly connecting its two mains voltage we cannot only see that these small motor shaft slowly rotates but also that it draws around 4.2 volts ampere 3 volt-ampere reactive and 2.9 watts now its current draw is rather small but on the oscilloscope we can still see the inductive phase shift of the current for which motors are pretty notorious since they mainly consist of inductors so the question is how can we decrease the reactive power of the modal NT solution is a capacitor by connecting its olia to a sinusoidal AC voltage it also creates a phase shift but this time the current is leading with an angle of 90 degrees that means the calculated power waveform also alternates between a load and generator function and therefore power also theoretically only oscillates from n to the capacitor due to its electrostatic fields which means no true power and since we know from the previous basics episode that inductors and capacitors basically oppose each other we would only have to draw the same reactive power with the capacitor as the inductor to get rid of it all so I did a small calculation to find out that I would need a 0.18 micro farad capacitor to cancel out the inductive reactive power the closest pannacotta where to 0.068 micro farad capacitors in parallel which I hooked up to the motor in order to find out that we successfully decreased the reactive power to one third of the original value of course such compensation makes much more sense for bigger motors or in the industry where you got loads of inductive loads but then you would be utilizing more automated compensation circuits but let's summarize in a complex plane we would have our true power P in watts alongside the real axis the reactive power Q in volt-ampere reactive then goes upwards for inductive loads and downwards for capacitive loads which is also the way they can compensate one another the apparent power s in volts and pair is then the resulting vector which also explains why the apparent power is not the sum of the true and reactive power but instead features the Protagoras theorem so what is left is the power factor which is mentioned on my energy meter now the power factor describes the relation between true power and apparent power but wait a minute doesn't that mean that the cosine Phi of our power triangle is also the power factor well for reactive power which only consists of phase shifts due to inductors and capacitors that is correct that is also why AC motors usually come with a cosine Phi rating rather than a power factor rating the reason why the power factor does exist anyway is that there can be cases where the reactive power is splits in its traditional reactive power as well as the deformed power deal an example for that we via my laptop power supply which after hooking it up and connecting it to my laptop draws a decent amount of reactive power even though its current waveform does not feature a phase shifts the problem this time is that the current is no longer sinusoidal which is a problem that many modern switch mode power supplies come with since they only need to charge up their energy saving capacitor near the peak of the mains AC voltage to understand this problem better though we need to be familiar with the Fourier series which mathematically looks like this as an example let's use this periodic square wave with a frequency of 2 pi now the function of this Fourier series is to dissect the regarded periodic function in two editions of sinusoidal functions well starting with the fundamental frequency and then going up to the second third fourth and so on harmonic this way by overlaying those individual functions we slowly recreate the original square wave which basically means every function consists of an infinite number of sinusoidal functions now since I'm not in the mood of mathematically analyzing our current waveform I simply utilized the current harmonics function of my oscilloscope to find out that because lots of harmonics with odd numbers that means we got many waveforms floating around with a higher frequency which just like an inductor and capacitor would only let power oscillates between the loads and power grids to get rid of this problem we can use a technique called PFC or power factor correction but that is a subject for another video since at this point you should be familiar with the basics of true reactive apparent and deform power and understand why those can be negative for our power grids if you enjoyed this video then don't forget to like share and subscribe stay creative and I will see you next timeI recently bought myself a new multimeter as an early Christmas gift but this is no ordinary multimeter it is an energy multimeter which means by connecting its three probes to suitable main socket adapter we can measure the electric power and also energy overtime of all hooked up AC appliances and while measuring the power draw of a few circuits I noticed that most of them feature a rather low power factor and thus draw comparatively much reactive power which is not desirable but what actually is the power factor or reactive power to begin with well stay tuned because in this electronic basics episode I will tell you all about this negative side effect of power electronics in what consequences it can have for our power grids let's get started let's start with a classical example for reactive power the transformer when I hooked up my first transformer to the power grids I was shocked to find out that I drew quite a lot of current on the inputs without even featuring a power drawing load on the outputs this example features a voltage of 228 volts and the current of 24 millions on the inputs which would equal a power of around 5.5 Watts that would get turned into heats that would be quite inefficient but while I was touching the transformer I realized that it was not getting as hot as the power draw would like you suspects the reason is that I measured the apparent power whose units is both unpaired which is quite literally how you calculated as well this apparent power consists of true power which for example heats up a resistor or moves an electric motor and reactive power which is almost not useful for anything to better understand it let's have a look at the mains voltage and more importantly the current the transformer drawers now please ignore the weird v-shape the transformer creates whose reason are the magnetic properties of its and instead let's focus on the paste shift between voltage and current as you can see the current is lagging with a phase shift of around 80 degrees the reason is that the transformer builds up a complex impedance consisting of a resistor and inductor but feel free to watch my previous basics video about the subject to learn more about that to make this example simpler though let's decrease the resistance of the impedance to almost zero and thus replace the transformer with an inductor by hooking it up to a suitable sinusoidal AC voltage and connecting the measurement equipments we can see how its current is a decent-looking sine wave with a phase shift of 90 degrees now I already told you that apparent power is calculated by voltage multiplied by current which I can do on the oscilloscope through the math function as you can see the resulting power waveform changes its polarity you will double the frequency and the areas underneath the waveform to zero are about the same size that means in the positive areas the inductor acts as loads by consuming power and in the negative areas the inductor acts as a generator by supplying power and since the areas are about the same the average power draw of the inductor is basically zero so no true power is being used all the inductor does is oscillating power between itself and the power source through its electromagnetic fields and this power is known as reactive power with the units volt-ampere reactive at this point you might be asking yourself if this power simply creates an oscillation and does not really waste power why should I care about it well the reason is that current does flow nevertheless which means our wires not only need to be able to handle the true currents but also the reactive current which means they need to be thicker and since the wire also features a small resistance as well as a few other components even reactive currents does create a small power loss by the way if we would look at the power curve of a traditional resistor we would see that the power would only be positive due to the same polarity of the current and voltage which means the resistor always acts as loads but anyway now we know that our transformer draws reactive power due to its inductance how can we fix it since the transformer is a rather complex electrical components all we have to do is to attach a load to its secondary sites and in acts more like a resistive loads that only draws a very small amount of reactive power so that is a bad example let's rather focus on the small synchronous motor I cut from a microwave by directly connecting its two mains voltage we cannot only see that these small motor shaft slowly rotates but also that it draws around 4.2 volts ampere 3 volt-ampere reactive and 2.9 watts now its current draw is rather small but on the oscilloscope we can still see the inductive phase shift of the current for which motors are pretty notorious since they mainly consist of inductors so the question is how can we decrease the reactive power of the modal NT solution is a capacitor by connecting its olia to a sinusoidal AC voltage it also creates a phase shift but this time the current is leading with an angle of 90 degrees that means the calculated power waveform also alternates between a load and generator function and therefore power also theoretically only oscillates from n to the capacitor due to its electrostatic fields which means no true power and since we know from the previous basics episode that inductors and capacitors basically oppose each other we would only have to draw the same reactive power with the capacitor as the inductor to get rid of it all so I did a small calculation to find out that I would need a 0.18 micro farad capacitor to cancel out the inductive reactive power the closest pannacotta where to 0.068 micro farad capacitors in parallel which I hooked up to the motor in order to find out that we successfully decreased the reactive power to one third of the original value of course such compensation makes much more sense for bigger motors or in the industry where you got loads of inductive loads but then you would be utilizing more automated compensation circuits but let's summarize in a complex plane we would have our true power P in watts alongside the real axis the reactive power Q in volt-ampere reactive then goes upwards for inductive loads and downwards for capacitive loads which is also the way they can compensate one another the apparent power s in volts and pair is then the resulting vector which also explains why the apparent power is not the sum of the true and reactive power but instead features the Protagoras theorem so what is left is the power factor which is mentioned on my energy meter now the power factor describes the relation between true power and apparent power but wait a minute doesn't that mean that the cosine Phi of our power triangle is also the power factor well for reactive power which only consists of phase shifts due to inductors and capacitors that is correct that is also why AC motors usually come with a cosine Phi rating rather than a power factor rating the reason why the power factor does exist anyway is that there can be cases where the reactive power is splits in its traditional reactive power as well as the deformed power deal an example for that we via my laptop power supply which after hooking it up and connecting it to my laptop draws a decent amount of reactive power even though its current waveform does not feature a phase shifts the problem this time is that the current is no longer sinusoidal which is a problem that many modern switch mode power supplies come with since they only need to charge up their energy saving capacitor near the peak of the mains AC voltage to understand this problem better though we need to be familiar with the Fourier series which mathematically looks like this as an example let's use this periodic square wave with a frequency of 2 pi now the function of this Fourier series is to dissect the regarded periodic function in two editions of sinusoidal functions well starting with the fundamental frequency and then going up to the second third fourth and so on harmonic this way by overlaying those individual functions we slowly recreate the original square wave which basically means every function consists of an infinite number of sinusoidal functions now since I'm not in the mood of mathematically analyzing our current waveform I simply utilized the current harmonics function of my oscilloscope to find out that because lots of harmonics with odd numbers that means we got many waveforms floating around with a higher frequency which just like an inductor and capacitor would only let power oscillates between the loads and power grids to get rid of this problem we can use a technique called PFC or power factor correction but that is a subject for another video since at this point you should be familiar with the basics of true reactive apparent and deform power and understand why those can be negative for our power grids if you enjoyed this video then don't forget to like share and subscribe stay creative and I will see you next time