Short video spoiler history: The beginning of modern warfare

Chapter 90 Transformers

During the Hongwu period, Jinling City.

The origin of mortar is very long, and its formula is constantly being improved. Currently, its main ingredients are lime, pottery powder and gravel.

The strength of cement must be stronger than that of mortar, otherwise there would be no need to invent cement.

However, its real strength lies in the steel structure placed in it, especially when laying the foundation. The amount of steel used makes it hard to imagine it not being strong.
The painters also saw some construction scenes in the images played on the sky screen, and they copied some of the steel structures.

A group of clerks copied down the proportions of concrete added in the comment section. It seemed that cement was divided into several types in later generations. The proportions of cement, sand, stone and water in different types were different. No one could figure out which type of cement Tianmu mentioned, so they could only let people test the strength one by one.

【If the generated electricity is not delivered in time, it will be wasted. 】

[However, due to the uneven distribution of natural resources, the places where electricity is generated and where it is consumed are often far apart, which obviously causes some trouble.]

[For example, my country's photovoltaic resources are mainly distributed in the northwest region, thermal power generation is mainly concentrated in the northern coal-rich areas, and more than 70% of electricity demand is concentrated in the relatively southeastern region]

[The power generation center is too far away from the power consumption center, and the loss of electricity in long-distance transmission will be very high, which has led to a 30% abandonment rate in Xinjiang and Gansu, the two provinces with the richest light resources in the northwest.]

[How to transport electricity generated in Xinjiang to Guangzhou, 4000 kilometers away? ]

[It still depends on high-voltage wires. According to high school physics, we know that the higher the voltage, the lower the power loss. Therefore, if you want to transmit electricity over long distances, you have to increase the voltage of the electricity.]

[Through the nationwide power grid, more than 5000 billion kWh of electricity was transported from the west to all parts of China, and the abandonment rate of solar power in Xinjiang dropped from 30% to 5%, and in Gansu it dropped to 2.4%]

[Of course, good things are expensive. my country has spent a total of 17 billion yuan on the construction of 2000 high-voltage lines, and will invest more than 4400 billion yuan in the future]

[Continuous high investment in research and development has made my country's UHV technology far superior to other countries. It is the only one in the world, and even the industry standards are set by my country]

[Do you know how high voltage electricity transmission works? ]

Ming, Jinling City.

Zhu Yuanzhang and others were a little confused. "Ultra-high voltage" was a new term, and this technology was in the leading position in later generations.

We can learn several pieces of information from the sky. First, there will be losses in power transmission, and the longer the distance, the greater the loss; second, solar power generation in later generations will be mainly concentrated in the northwest region; third, high-voltage transmission and ultra-high-voltage transmission can effectively alleviate the problem of power loss, especially ultra-high voltage.

"Is this a popular science video about ultra-high voltage technology?" Many people were secretly excited because this is a unique technology in the world.

“That’s pretty clear how it works.”

Liu Ji smiled in his heart. If UHV technology was really so important, then the level of confidentiality must be very high and it would be impossible for ordinary people to access it. In fact, the various technologies that Tianmu had seen were almost all outdated, which was a good proof of this point.

However, compared with technology, the popularization of principles is relatively more important.

In the video about the telegraph, the problem of electricity being unable to be transmitted over long distances was also mentioned. The solution at the time was to install a relay every 100 kilometers.

Liu Ji vaguely felt that this high voltage and ultra-high voltage were somewhat related to the structure of the relay.

This is the sentence that Tianmu had said before: "Electricity generates magnetism, and magnetism generates electricity."

Could it be like a relay, regenerating electricity every 100 kilometers?
[We actually use transformers to increase and decrease the voltage of current. The working principle and underlying logic of transformers are very simple, that is, electricity generates magnetism and magnetism generates electricity.]

[For example, this is the basic structure of a transformer, which consists of an iron core and windings on the left and right sides. The wires on the left and right sides are not interconnected.]

[The principle is to use the current passing through the wire to form a magnetic field, and then wrap the wire around the left iron core to increase its magnetic field, and then the alternating current will continuously switch the switching direction, causing the wire wrapped on the right to induce current]

[We call the winding on the left the primary winding, and the winding on the right the secondary winding]

[The core of the transformer to achieve voltage step-up and voltage step-down is the ratio of the number of coil turns between the two windings. For example, if the input voltage is 220V, if you want to output 440V, then the ratio of the number of coil turns on the left and right must be 1:2]

[On the contrary, if you want to achieve voltage reduction, the left coil can be higher than the right coil. The specific voltage can be determined according to the coil ratio. If the ratio of the two coils remains unchanged, the voltage of the induced electricity will also remain unchanged.]

[It should be noted that the wires of the left and right windings need to be isolated with insulating materials to prevent short circuits]

[For example, the electricity generated by power plants in our country must be stepped up by transformers before being transmitted through high-voltage wires. After reaching the destination, it is stepped down by transformers for safety before being delivered to each household.]

[This is the working principle of voltage step-up and voltage step-down. In fact, the technical difficulty of UHV is never in principle.]

[The transmission line is the core component of the UHV system. Large-section conductors are used to reduce resistance, or composite materials are used to improve conductivity. Materials are of utmost importance. If the materials are wrong, everything will be in vain. This is why we are the only one in the world that can make it.]

The video ended after the video was played again. Ming, Jinling City.

Everyone in the science department was furious, holding their chests and looking dizzy. No, where are the materials? Why don't you tell me about the materials?
Liu Ji sighed, it is indeed so.

"However, Tianmu said that the voltage increase and decrease can be determined based on the turns ratio. This means that the number of turns on the right is determined based on the number of turns on the left. Then how should the number of turns on the left be determined?" Du Ping from the Science Department asked his doubts.

“例如同样是升压5倍，左边右边的匝数可以是20/100圈，也可是200/1000圈。”

The difference in the number of circles is huge, and the cost is even more different. Or in the most extreme case, is it okay to only wrap one circle on the left?

Du Ping thought about it and felt that it would not work. Tianmu also had an actual transformer demonstration, and it looked like the number of turns of the coil was quite a lot. If it was possible to wind only one turn, then the real transformer would not look like this.

After this was said, everyone was confused, as Tianmu had indeed not mentioned this.
Liu Ji also frowned and thought. There were still some people with real talent in the science department. This question was very to the point and directly asked the most crucial thing.

How can this be good?

Zhu Yuanzhang ordered people to record this issue. I don’t know if the young people who were doing popular science at Tianmu forgot about it or thought it was not important at all, so they didn’t mention it at all.

Everyone looked at each other in bewilderment. They really knew very little about this topic. It was also their first time seeing a transformer, and it was not easy for them to understand its principles at once. Now it was obviously difficult to ask them to explain it in detail.

The bags under the eyes of Sun Chuanshi and others from the Science Department looked even darker, and they had no choice but to turn their gaze to the comment section, hoping to get answers there.

During the Zhenguan period, Chang'an City.

Everyone was also worried about how to determine the number of turns of the left coil.

Cheng Yaojin watched the civil officials worrying about this matter and did not dare to disturb them. He just sighed in his heart that this thing in later generations was really not something that people could learn. No wonder those kids were so tired of studying.

He knew that electromagnetism was only a branch of classical physics. However, a single electromagnetic conversion could cause so much trouble. He didn't know how much trouble he would have to deal with other issues such as mechanics, optics, thermodynamics, etc.

Of course, one of the reasons why everyone is in so much trouble now is that the videos viewed by Tianmu are too scattered and unsystematic, or incomplete.

But from another perspective, later generations discovered that the scholars of these disciplines were indeed gifted. Just listening to these contents makes me sleepy.

“This is really not the technology that should be used in this era.”

The generals nearby heard his mumbling and all looked confused.

Li Shimin discussed the issue with his civil officials but had no ideas, so he had to place his hopes on the comments section.

"Will there be any loss? Can one kilowatt-hour of electricity generate one kilowatt-hour of electricity?"

《Yes, about 2%》

"So is it better for a transformer to have fewer windings? Save on enameled wire"

Li Shimin and others were excited for a moment, and couldn't help but clenched their fists, and then waited for the curtain to unfold the remaining comments and returned disappointed.
More than one person in Tianmu mentioned a similar problem to the one they encountered, but no one answered it.

The screen continued to turn down, and many people asked related questions. Finally, Li Shimin's eyes fixed on an answer, which was a formula: N=10000/4.44FBS, where N-turns per volt, F-AC frequency (50HZ in my country), B-magnetic flux density (silicon steel sheet 1.2-1.7), S-core cross-sectional area (unit: square centimeters).

Li Shimin rolled up his sleeves and started copying down the information. As for why there were two constants 10000 and 4.44, no one could answer. They didn't even know how to measure the magnetic flux density.

However, there is a basic range for reference. If it doesn’t work, just try a middle value.

It was not until this moment that Li Shimin slowly came to his senses and his mood became solemn. He thought that physics was a very easy subject in later generations, but he did not expect that the subject mentioned by Tianmu before was relatively simple.

Just the study of electromagnetism is probably enough to give the people in the science department a lot of trouble, because there is still no method to measure the various values ​​of electricity.

And is what we see necessarily all there is to electromagnetism?

The answer is obvious.

My head hurts a bit.
Ming, Jinling City.

The people in the Science Department were also a little confused at the moment. Even if there were corresponding annotations, they still couldn't understand it.
What is the frequency of alternating current? What is magnetic flux? Why are there two constants in front of it? How do you measure density?
You can't just use the value given by Tianmu, right? What's the difference between that and salted fish?
Sun Chuanshi ruthlessly complained in his heart, "Let's get a fragile college student, the kind who majors in physics."

"The man who invented genius is really a transformer [狗头]"

(End of this chapter)