Hello, I am Jeon from Dasan Edu. When learning about electricity, we often hear terms like single-phase and three-phase. What exactly is the difference between the two? Single-phase consists of one component, while three-phase consists of three components. Is it just the number that differs? Let's organize our understanding from the power plant, where electricity is generated, all the way to where it is used. I hope this video will help you clarify the concepts of single-phase and three-phase electricity. 

First, let me compare and explain single-phase and three-phase systems. What are the differences? To understand how electricity is generated, we need a coil and a changing magnetic field around it. Of course, solar power generation is a bit different, but in general, we...

Using beautiful thermal power and nuclear power generation, the principle is the same: they all generate electricity by rotating a machine. Here, I have a coil, meaning a wire that I have wound up, and then I will place a magnet of this shape in front of it. Now, let’s try rotating this magnet. Of course, there are N and S poles in this magnet. When I rotate the magnet, you can see that the change in the magnetic field affects the coil, and electricity is generated in this coil. In fact, this alone is incredibly fascinating. Why? Because in this coil, there are electrons, and due to the change in the magnetic field, these electrons start to move around. Later, when we look at these two wires from the outside, we can see how a waveform is created between them.

이제 만들어지는 것을 볼 수 있습니다. 자, 이것을 우리가 이제 어떤 하나의 매치 미 형태, 즉 물의 적 형태라고 해서 이제 상이라고 부르게 됩니다. '상'이라고 한 것은 어디에서 사용되냐면, 우리 주변에서 관상을 본다, 이런 말 들어보셨죠? 사람의 얼굴을 봄으로써 그 사람이 가지고 있는 재능이라든지, 앞으로의 성공 여부라든지, 이런 것들을 바라볼 수 있는 것을 우리가 흔히 관상을 본다 이렇게 이야기하게 됩니다. 아, 그 삶과 똑같은 한자어를 사용하게 되는데요. 이 물의 적으로는 어떤 안정된 현재의 상태를 우리가 '상'이라고 하게 됩니다. 액체 상태, 기체 상태, 고체 상태도 하나의 '상'이 되는 거죠. 전기에서는 몇 개가 도대체 일을 하냐라고 하는 것을 통해서 우리가 '상'을 구분하고는 합니다. 실제로 우리 집에 들어오는 전기는 두 가닥이지만, 두 가닥 중에서 하나는 기준 전이가 되고요, 나머지 하나가 이렇게 높고 낮음을 반복하게 됩니다.

As we work, we refer to it as a single phase, or in other words, we call it a phase and now it is also referred to as one phase. It can also be called one page. However, the three phases are a bit different; they have a more complex shape compared to the single phase. When creating what is referred to as two, three phases, a larger coil is needed. For example, if we were to create one, we would then divide this circular shape into three triangles. Here, we would wind the coil in this shape, and then we would also wind another coil at a specific position. After that, we would place a magnet inside and rotate it. Of course, here we are considering the speed and the north pole. Now, this coil is facing the north side, but it will soon change direction. After a little while, it will...

Now, we will direct it this way. By continuously rotating, energy will be generated from this side first, then from this side, and then from that side. Since it is shaped like this, the phase difference at each angle will be 120 degrees. If I were to draw a waveform like the one on the left, it would look like this. Let's organize what we have one by one. For convenience, let's call this one L1, and then let's call this one L2. The one on our side will be L1, then this one will be L2, and this one will be L3. Now, if I pull the waveform from here and then pull the waveform from here, and then pull the waveform from L1, and then pull the waveform from L1 here as well, we will have L1 on this side, L2 on this side, and L3 on this side.

각각의 파형의 모양은 이렇게 됩니다. 첫 번째 R1 이자, 이런 파형으로 이제 모양이 만들어졌습니다. 그것이 바로 L 원의 모양이고요. 조금 있다가 129의 상차라고 했으니까, 여기 이제 두 번째 L2가 모양의 자, 여기까지가 90도고 이쪽이 180도니까, 한 그 가운데 여기에서 파형이 이렇게 만들어지게 될 겁니다. 자, 이렇게 만들어지는 것을 이제 우리가 L2라고 할 수 있고요. 마지막으로 이제 제가 빨간색으로는 L3 모양을 나타내 볼게요. L3는 그것보다도 또 120도 더 뒤지게 되니까, 한 요 정도에서 이제 출발을 하겠죠. 이 정도에서 출발을 하면 이제 요런 모양을 우리가 이제 그릴 수 있겠죠. 앞에까지 마저 그렇게 되면, 이런 모양을 이제 우리가 만들 수 있고, 앞에까지 마저 그렇게 되면 이제 이런 모양을 만들 수 있게 됩니다. 자, 이게 바로 L3의 모양이 되고, 이제 우리가 보는 관상처럼 볼 수 있습니다.

Because there are 1, 2, or 3 forms of phase created, we now express this as three-phase. In three-phase, the remaining vertices are grouped together, forming a single entity. When we extend this, it does not represent any specific phase but is instead referred to as neutral, which we denote as the neutral line. 

So, how does the electricity we actually use work? The voltage between L1 and L2 is 380 volts, and the same goes for L2 and L3, as well as L1 and L3. Additionally, the voltage between L1 and the neutral (N), L2 and the neutral, and L3 and the neutral is all 220 volts. We call this line-to-neutral voltage, and we refer to it as phase voltage. Therefore, whether it is single-phase or three-phase is primarily determined by the configuration we create.

At the power plant, we create a three-phase power supply. We bring in a three-phase 380 volts supply, and when we use it here, we utilize the Aaron Elder S3 system. If we decide to use 220 volts, we connect one of the lines to get 210 volts. Now, let me clear this area and show how we bring in electricity. If the power line has sufficient strength, we will have L1 coming out like this. Let's add some colors. Next, L2 will come in like this, and then L3 will also come in slightly above, like this. Finally, if everything is connected properly, and if we need to operate a large load, like a motor in the building, we will receive 380 volts from R1, L2, and S3 to operate a large motor.

Television, refrigerator, and office equipment are all examples of general electrical appliances. For instance, by removing the L1 and N lines, we can power single-phase electrical devices like an OTV. Additionally, by using L2 and removing N, we can also use single-phase electricity for appliances like refrigerators. Furthermore, we can create single-phase electricity to operate devices like a motor by utilizing L3 and N. Therefore, whether you are dealing with three-phase or single-phase electricity depends on how many phases are represented externally. In our homes, although there are two wires coming in, only one actually represents a phase, which is why we refer to it as single-phase. On the other hand, in industrial settings or large buildings, power is supplied through three wires, and since this configuration represents three phases, we call it three-phase electricity.

You could say that this is what we are discussing. So, are there other phases? Yes, if we use two phases, we can refer to it as a phase, and we also use terms like single-phase, three-phase, and so on. We can also create four-phase, five-phase, and six-phase systems. Generally, we can refer to all of these as phases. Therefore, we can call them single-phase, two-phase, three-phase, four-phase, five-phase, and six-phase. 

Electricity not only has to be generated, but the receiving end must also adhere to certain rules. This is important because both the sending and receiving ends need to have consistent specifications in order to use electricity effectively. Therefore, what we typically use are the single-phase and three-phase systems. 

Now, if you encounter the term phase in your surroundings, or if someone asks whether your home uses single-phase or three-phase, you should be able to respond confidently. Please refer back to today's content, and if you have any further questions, there are indeed more specialized aspects to explore.

If you look into the content, there will be information that you can fully understand. So, during this time, I hope you can understand that the concept of Ah comes to you in this way. I will explain from here. At Dasan Edu, it will be at 8 o'clock. Thank you.

단상과 3상의 차이. 쉽게 설명해보겠습니다.

(주)다산에듀 대표. 전기분야 기술강의/ 
고용정책학박사/ 전기기능장/ 
전)OOO대학겸임교수
'찐초보 걸음마전기', '찐초보 생활전기' 저자
