Beat method

This is the second article on the application of resonances to the destruction of physical objects.

The first article "Russian trail of the virus Stuxnet" was of an introductory nature, and was designed for a wide non-professional audience.

It is time to get acquainted with this method in detail, but first, watch the video with a clear example of resonance, then I think the topic of the article will become clearer, because it’s better to see once than read a hundred times ... 

Here's the video:


Here's more:



So please treat resonance with respect.

 

Such a famous, unknown Stuxnet

The world-famous virus Stuxnet has now turned into a kind of horror story, everyone knows about it, but nobody fully understands how he managed to secretly destroy centrifuges to enrich uranium over the course of two years. This is not even sabotage, but a more sophisticated method of sabotage - sabotage.

Just think over the course of two years, hundreds of centrifuges are constantly breaking down, all production schedules are broken, experts call it “on ears” and cannot do anything until a message is received from Belarus about the detection of a virus whose combat load was the internal software update modules for industrial automation company Siemens.

Later, this virus was called Stuxnet. Understood using the method of infection, with the methods of its penetration to the kernel level, and the method of breaking the password protection of Simatic S7 controllers in the local network. Something was understood from what the firmware of the group centrifuge group controller software updated by the virus does.

But no one has yet explained the physical method of disabling equipment in this act of sabotage. Therefore, we will try to deal with this most important riddle.

 

What we know

This controller Simatic S7 complete with peripheral modules:

The microprocessor unit itself is a box with a blue key, the rest is the periphery. The microcontroller software (using a special STEP 7 interpreter language) is placed in the internal flash memory. The software and firmware firmware of the controller itself is updated via the network, or physically, through a removable flash drive. Such controllers were grouped control devices immediately for the 31 gas centrifuge.

But the centrifuges were directly broken through other devices, - a frequency converter for the operation of an electric motor, approximately as follows:

This is how frequency converters (converters) for asynchronous electric motors of various powers look like. The name implies the functional purpose of this device, it converts the voltage of a standard network (three phases 360V) into a three-phase voltage of a different frequency and a different rating. The voltage conversion is controlled by signals from the network, or is set manually from the control panel.

One Simatic S7 controller controlled the group (31 device) of the frequency converters at once, respectively, was a group of CUs for the 31 centrifuge.

According to experts, the semantics of the software of the group control controller was strongly modified by the Stuxnet virus, and they considered the immediate cause of the centrifuge breaks to be the output of modified controller software. Simatic S7 commands of group SU on frequency converters.

Modified by the virus, the control unit's software once during the five-hour interval on 15 minutes changed the frequency of operation of each frequency converter and, accordingly, the frequency of rotation of the centrifuge electric motor connected to it.

Here is how it is described in the research firm Semantics:

Thus, it changes from 1410Hz to 2Hz to 1064Hz and then over again. 807 Hz and 1210 Hz.

So the motor speed changes from 1410Hz in 2Hz steps to 1064Hz and then reverses back. As a reminder, the normal operating frequency at this time was maintained between 807 Hz and 1210 Hz.

And Semantics makes a conclusion based on this:

Thus, Stuxnet sabotage

(Thus, Stuxnet sabotages the system by slowing or speeding up the engine to different speeds at different times).

For modern programmers who know physics and electrical engineering only in the volume of secondary school, this is probably enough, but for more competent specialists such an explanation is not consistent. Changing the rotational speed of the centrifuge rotor within the permitted range and a short-term excess of the operating frequency by 200 Hz (about 15%) from the nominal value in itself cannot lead to massive equipment breakdowns.

 

Few technical details

This is a cascade of gas centrifuges for the production of enriched uranium:

There are dozens of such cascades in uranium enrichment factories, the total number of centrifuges passes for 20-30 thousand ...

The centrifuge itself is a fairly simple device, its schematic drawing:

But this constructive simplicity is deceptive, the fact is that the rotor of such a centrifuge, about two meters long, rotates at a speed of about 50 000 revolutions per minute. Balancing a rotor with a complex spatial configuration, almost two meters in length, is a very difficult task.

In addition, special methods of rotor suspension in bearings are required; for this purpose, special flexible needle bearings are used complete with a complex self-centering magnetic suspension.

For the reliability of gas centrifuges, the main problem is the resonance of the mechanical structure, which is associated with certain speeds of rotation of the rotor. Gas centrifuges are even categorized on this basis. A centrifuge operating at a rotor speed above the resonant one is called supercritical, below - subcritical.

No need to think that the frequency of rotation of the rotor is the frequency of mechanical resonance. Nothing of the kind, mechanical resonance is associated with the speed of rotation of the centrifuge rotor through a very complex relationship. The resonance frequency and rotor speed can vary by an order of magnitude.

For example, a typical resonant region of a centrifuge is a frequency within 10Hz-100Hz, while the rotor speed is 40-50 thousands of revolutions per minute. In addition, the resonance frequency is not a fixed parameter, but a floating one; it depends on the current mode of operation of the centrifuge (composition, density of the gas temperature in the first place) and backlash in the design of the rotor suspension.

The main task of the equipment developer is to prevent the centrifuge from operating in modes of increased vibration (resonances), for this, automatic emergency blocking systems for vibration level (strain gauges), operation at rotor speeds causing resonance of the mechanical structure (tachometers), increased current loads of the motor ( current protection). 

Emergency systems are never combined with the equipment responsible for the normal operation of the installation, they are separate, usually very simple electromechanical systems for stopping work (just emergency switches). So do not programmatically disable and reconfigure them.

The colleagues from the USA and Israel had to solve a completely non-trivial task, - destroy the centrifuge without at the same time triggering protective automation.

 

And now about the unknown, how it was done

With the light hand of the translators of the scientific center "NAUTSILUS", who translated the research of the Symantik specialists into Russian, many specialists who did not read the Symantik report in the original had the opinion that the accident was caused by the operating voltage frequency reduced to 2Hz to the centrifuge electric motor.

This is not the case; the correct translation is given at the beginning of the text of the article.

And in principle, it is impossible to reduce the frequency of the supply voltage of a high-speed asynchronous electric motor to 2Hz. Even a short-term supply of such a low-frequency voltage to the windings will cause a short-circuit of the windings and an overcurrent protection.

Everything was made much smarter.

The method of excitation of resonance in electromechanical systems described below could claim to be new, and I am considered to be its author, but the authors of the Stuxnet virus most likely have already applied it, so, alas, all that remains is to plagiarize ...

And nevertheless, I explain on fingers, spending at the same time an educational program on the basics of physics. Mentally imagine a massive load, say a ton, hanging on a cable, suppose a long 10 meter. We have the simplest pendulum with its own resonant frequency.

Suppose further that you want to shake his little finger, applying force in 1kg. A single attempt will not lead to any visible result.

So you need to push it repeatedly, putting efforts into it in 1k, say 1000 times, then you can assume that such a multiple force will be equivalent in sum to a single force application per ton, which is quite enough to build such a pendulum.

And so, we change tactics, and start repeatedly pushing the suspended load with the little finger, each time putting effort into 1kg. We will fail again, because physicists do not know ...

And if they knew, they would first consider the period of oscillation of the pendulum (the weight is absolutely unimportant, the suspension of 10 meters, the force of gravity 1g) and began to push the load with this little finger with the little finger. The formula is well known:

Minutes through 10-20 this pendulum weighing in ton swings so that “Mama Do not Cry.”

And it is not necessary to press the little finger on every swing of the pendulum; this can be done both once and after two, and even after a hundred oscillations of the pendulum. It is just that the time for the buildup will increase proportionally in this case, but the effect of the buildup will be completely preserved.

And I will surprise people who know physics and mathematics in the secondary school (the level of knowledge of a typical modern programmer), the period of oscillations of such a pendulum does not depend on the amplitude of oscillations, swing it a millimeter or meter from the point of rest, the oscillation period and, accordingly, the oscillation frequency of the pendulum is constant.

Any spatial structure has not even one, but several resonant frequencies, in fact there are several such pendulums in it. Due to their technical features, gas centrifuges have the so-called fundamental resonance frequency of high quality (they effectively accumulate oscillation energy).

It remains only to swing the gas centrifuge at the resonant frequency with your finger. A joke, of course, if there is an electric motor with an automatic control system, then the same thing can be done much more inconspicuously.

To do this, you need to increase / decrease the speed of the electric motor in spurts (as the virus did, according to 2Hz) and produce these jerks with the resonance frequency of the mechanical design of the centrifuge.

In other words, it is necessary to output the frequency of the mechanical resonance to the motor using a variable frequency frequency converter. The moment of force arising in the motor when the frequency of the supply voltage changes will be transmitted to the case with the frequency of mechanical resonance and gradually resonant oscillations will reach the level at which the installation will begin to collapse.

Frequency fluctuations around a certain average value are called “beats”, this is the standard effect of any frequency converter, the frequency is said to “walk” within certain limits, usually no more than tenths of a percent of the nominal value. The saboteurs disguised under these natural frequency beats, their own, artificially introduced, modulation of the frequency of the electric motor and synchronized it with the frequency of the mechanical resonance of the spatial design of the centrifuge.

I will not go into the subject any more, otherwise they will accuse me of writing step-by-step instructions for saboteurs. Therefore, outside the discussion I will leave the question of finding the resonant frequency for a specific centrifuge (it is individual for each centrifuge). For the same reason, I will not describe the “fine” adjustment method when you need to balance on the verge of triggering an emergency protection against vibrations.

These tasks are solved through programmatically available current output voltage sensors installed in frequency converters. Believe the word - it is quite realizable, it is only in the algorithms.

 

Again about the accident at the Sayano-Shushenskaya HPP

In a previous article, it was hypothesized that a hydroelectric station accident was caused by the same method (resonance method) as in a uranium concentration plant in Iran, using special software.

This of course does not mean that the same Stuxnet virus worked here and there, of course not. The same physical principle of the destruction of an object, the artificially induced resonance of a mechanical structure, worked.

The presence of resonance is indicated by the presence of the unscrewed nuts securing the turbine cover and the indication of the only operating sensor at the time of the accident of the axial vibration sensor.

Taking into account the coincidence of the time and causes of the HPP accident with the fact of sabotage at the Iranian uranium enrichment plant, the continuous vibration control system turned off at the time of the accident, the operation of the unit under the control of the automatic control system of the turbine unit, it can be assumed that the resonance was not an accidental phenomenon, but a man-made one.

If this assumption is true, then, in contrast to the situation with gas centrifuges, the task of destroying a turbine unit required manual intervention. The equipment available at the hydroelectric station did not allow the tamper software to automatically detect the individual resonance frequency and then keep the vibrations in the emergency mode without triggering the alarm sensors.

At the hydroelectric power station, the work of the sabotage software required the use of the “human factor”. Someone somehow had to turn off the vibration control server, and before that, transfer to the developers of the sabotage software the resonance parameters of a specific turbine unit, which were removed from it six months before the accident during scheduled maintenance.

The rest was a trick.

No need to think that the resonance occurred in the very body of the turbine rotor, of course not. Was caused by the resonance of the water layer, saturated with elastic cavitation cavities located between the turbine rotor and the blades of the guide vane.

It is easy to imagine such an analogy, below is a spring from cavitation cavities between the turbine rotor and the blades of the guide vane, and this spring is supported by a column of water one hundred meters high. It turns out the perfect oscillating circuit. To shake such a pendulum system is a very real task.

It is because of this resonance. ALL the blades of the guide vane were broken, and not mechanically, from impacts, but broken by dynamic load. Here are photos of these broken blades; there are no traces of mechanical shocks on their surfaces:

The broken blades of the guide vane blocked the drain hole of the turbine, and it was from this unforeseen circumstance that the accident began to develop into a catastrophe.

The turbine rotor became similar to the screw of a supertanker, and began to rotate in a “closed can of water” having a mass of one and a half thousand tons and a rotation speed of 150 revolutions per minute. In the working area of ​​the turbine, such an excessive pressure of water was created that the lid was blown off, and the turbine itself, according to eyewitnesses, together with the generator rotor (a machine in one and a half thousand tons) flew up to the ceiling of the machine hall.

What was further known to all.

Comments

[shurup]

So, unobtrusively, from the bridge through the centrifuge to the turbine rotor, they are trying to suggest that it was not the specific officials who were guilty, but the malicious intrigues because of the cordon or, better, the activities of the lone psycho who created the virus.
According to the classics of the genre, loners are computer geniuses unfairly dismissed by stupid and evil bosses.

[DAGESTAN333]

Well, yes, yes ... let's concentrate on the officials who traditionally squint in Russia, and the fact that such objects always have multi-level protection from slobs, bukhariks, deb-lows, and the fact that without purposeful sabotage is such a principle not possible, we will try to put on the second and third plans ...

[postman]

Quote: DAGESTANETS333

and the fact that such facilities always have multi-level protection from slobs, bukhariks, deb-fishing, and that without deliberate sabotage

no protection against:
Violations of terms and standard maintenance
Violations of routine inspections
-etc
- from postscripts (did "repair")
-from Chubais and Co.

[Geisenberg]

Avtyr, you just don’t need to expose the IDDOT of people who know programming. Huh? These illiterate and generally dark people, as it were, wrote stuxnet ... before you had to deal with frivolousness and fraud. You know physics in the volume of the school and vocational schools - well done, a flag in your hands and a drum on your neck.

[postman]

Quote: Geisenberg

Avtyr, you just don’t need to set up an I.D.O.T.A.mi here

In the direction of the arrow, as I understand it to me.
In terms of meaning - I didn’t understand anything, like after an hangover
"Avtyr" is who? or what?

Quote: Geisenberg

I.D.O.T.A.M. of people who know programming

And who are you, what are you doing "programming"?

Quote: Geisenberg

as they would have written stuxnet

Yes hi with them, wrote, and then what?

Quote: Geisenberg

You know physics in the volume of school and vocational schools - well done, a flag in your hands and a drum on your neck

Well, if we suddenly became on "You" ...
I do not know physics in the volume of schools and vocational schools
A drum to zanutte yourself between the big toes, until fully fixed
Alles Klar?

[dv-v]

very relevant, and most importantly - a "smart" comment, it is appropriate here to recall how purposefully and consistently bypassed the "multilevel protection from slovens, bukhariks, deblovers" of the 26th Arpel of 1986. at the Chernobyl nuclear power plant.

[studentmati]

Quote: shurup

So, unobtrusively, from the bridge through the centrifuge to the turbine rotor, they are trying to suggest that it is not specific officials who are guilty, but malicious machinations because of the cordon or, better, the activities of the lunatic psycho who created the virus. According to the classic of the genre, computer geniuses are loners , unfairly dismissed by stupid and evil bosses.

Very competently and subtly commented!

[basil200]

The NSA or SkyNet are to blame for everything. BUT not officials.

[kekse]

Quote: basil200

The NSA or SkyNet are to blame for everything. BUT not officials.

Well, yes, and the angular velocity sensors on the proton, too, accidentally put their feet upside down, they are round pancake.

[oblako]

The comments are surprising. In this case, the main thing is not who, but how. It is easy to declare an official guilty, you can even punish him cruelly, only the resonance from this will not go anywhere ...)) If there is a reason, and it is known, then it is necessary to put sensors on centrifuges or other terminal devices that fix the presence of "parasitic resonant" oscillations supplying electric motors stress, and to level them automatically, this is also not a very difficult task in fact. Then voltages will be needed that provoke resonance, which will be invisible to more sensitive sensors, and then they will become of such magnitude that they will not be able to solve their destructive task, and the speed of centrifuges can be changed according to a random law. Although the destructive manifestation of resonance is a force of course ... and the phenomenon is not new in practice. Remember the "flutter" in aviation, for example ... That would be to utilize this force not only for destruction ... these ideas, very few people need, unfortunately.

[oblako]

The comments are surprising. In this case, the main thing is not who, but how. It is easy to declare an official guilty, you can even punish him cruelly, only the resonance from this will not go anywhere ...)) If there is a reason, and it is known, then it is necessary to put sensors on centrifuges or other terminal devices that fix the presence of "parasitic resonant" oscillations supplying electric motors stress, and to level them automatically, this is also not a very difficult task in fact. Then voltages will be needed that provoke resonance, which will be invisible to more sensitive sensors, and then they will become of such magnitude that they will not be able to solve their destructive task, and the speed of centrifuges can be changed according to a random law. Although the destructive manifestation of resonance is a force of course ... and the phenomenon is not new in practice. Remember the "flutter" in aviation, for example ... That would be to utilize this force not only for destruction ... these ideas, very few people need, unfortunately.

[Mature naturalist]

The author is a stubborn dreamer. Who told him that the chastotniks are on centrifuges. And for hell are they (chastotniki) needed in centrifuges? His determination would be for the benefit of society.

[Dazdranagon]

50000 rpm - how to achieve without emergency?

[Asgard]

I have a similar microcontroller on the Italian stone-cutting machine, but it is possible to change the program on it only by directly connecting, and so it gives information about the work and status bar .... That is, the virus will not be able to register there itself ....
This is a fairy tale, for the public (illiterate)), in fact, it is a sabotage of the manufacturer (that is, they initially prescribed the algorithms of work, which suddenly became destructive for centrofuges (which is unlikely)), or microcontrollers replaced "knowledgeable people" with the prescribed (again) ) program ....

Well, at the Sayano-Shushenskaya state district power station, diversion is unequivocal, and the studs were broken off not by vibration, but by water hammer, I will explain how the engineer and the sabotage specialist (saboteur)) - apparently, explosive was introduced into the water inlet channel (a little)), which was blown up, an air bubble appeared that exposed the turbine blades for a split second. the next contact with water broke off the blades and from the blow broke the turbine mounts ....
Too everything happened all of a sudden. The weight of generator No. 2, on the contrary, allowed some of the People to be saved, and the rest of the cars did not collapse, although they were on a common basis ....

Resonance is a studied phenomenon, engineers know everything about it, there are the necessary mechanical and electrical fuses in order to prevent resonance from developing, it develops for a long time, both the equipment and the people nearby feel its growth ...

This is my opinion ,,,

[StolzSS]

Certain things can be done remotely, but the main work is always done by a person. And in case of sabotage, this person has a special character warehouse and a very special look at his work. Without human deliberate sabotage intervention, such things are impossible in principle ... well, or those who are responsible for safety are complete stupid people who lie ...

[Papakiko]

Quote: Asgard

its growth is felt by both technology and the people nearby.

Like, the whole station confirmed, in unison, an almost outgoing vibration from the "take off" hydraulic unit.

Quote: Asgard

Well, at the Sayano-Shushenskaya state district power station, diversion is unequivocal, and the studs were broken off not by vibration, but by water hammer

Quote: Asgard

apparently, an explosive (a little)) was introduced into the water inlet channel on the dam, which was blown up, and an air bubble appeared that exposed the turbine blades for a split second. the next contact with water broke off the blades and from the impact broke the turbine mounts

http://ensafe.ru/index.php?option=com_content&view=article&id=11:shges&catid=8:s
hges & Itemid = 13
Here, the explosive development of the tragedy at the hydroelectric station was painted every second.
The first and main factor: these are efficient owners. Everything starts with them and ends with them too. Even the manual shut-offs of pressure pipelines were shut by the station staff from 08:35 to 09:30 !!!
And people died.
In general, the author pointed the way in the right direction, but this is not applicable everywhere.

[valerei]

Asgard, if you believe what was leaked to the media, the former chief engineer of the hydroelectric power station said: "This turbine gave vibration from the very beginning, but there was a plan to start up the hydroelectric power station, awards and orders were threatened, and the acceptance certificate was signed." Therefore, knowing about such a feature of this turbine, it was not turned up to the resonant frequency and it worked successfully. At that time, there was an accident at some hydroelectric power station in Siberia and the frequency began to drop in the looped power grid. And then the greed of the owners of the hydroelectric power station decided everything. There was an order to increase the speed of all the turbines of the Sayano-Shushenskaya, incl. and this turbine. The management of the hydroelectric power station knew about the presence of vibration, but, perhaps, relied on the Russian "maybe". This accident is a pure crime ch. hydroelectric power plant engineer.

[lexat7]

Twenty-five again - part two.
"to destroy the centrifuge without triggering the protective automatics" is the main question. By the way, Siemens also produces microprocessor protection units. Of course, if the controllers, protections, frequency converters are all the same - the version takes place (for centrifuges). But frequency changes, even short-term ones, can be tracked on oscillograms, again if these oscillograms are taken from other devices, not from Siemens.
In such a development of events for a hydraulic turbine, I do not believe. The author did not convince at all . The flow of water and the electric motor, well, completely different things

[saag]

Everything, as always, rests on money, if you need to do something, and this entails certain costs, then as a rule, until the fried rooster pecks, it is postponed again and again or completely forgotten

[carbofo]

Computerization of everything and everything is a bad thing, we do not control it.
Why did Microsoft put so much money on Skype? after all, he was already caught for transferring data to the authorities.
Google and others are the same.
The virus damaged the centrifuges, how much could not be done on the old like poop mammoth SSHHPP.
It is clear that the methodology is different but the principle is the same, and if there were no control computers at the SShHPP, then who? like there is information, but where to apply is unclear.
It was somehow here if Rogozin himself didn’t say that the Western air defense systems were disconnected when they were pointed at American planes !! Well, I somehow realized what you still need to understand.

[Monster_Fat]

Things are much worse. The same Rogozin recently mentioned that precision machining machines that were purchased abroad were remotely shut down for defense enterprises and rendered unusable (there was, in fact, an interesting story worthy of a "spy novel"). And equipment worth tens of millions of dollars in one second turned into scrap metal. And we no longer have our own machine tool industry. Rogozin and urged him to restore. Oh well. This is not a matter of one year. In addition, tracking and spy devices have been found in Chinese-made equipment that is used in the defense industry and the maintenance of military equipment, not to mention "software bugs."

[alex0000]

As for the "saboteur machines" - it seems to me that they were bought through dummies through "gray channels". Otherwise, when buying any serious equipment "on the white", the manufacturer sends installers who do the initial installation and commissioning of the equipment and only after that the manufacturer assumes obligations for warranty service. Further, in the event of a breakdown, a team of technicians arrives to solve most of the problems on site. So, in this situation, there can be no disconnection and damage in principle, because in case of downtime due to the manufacturer's fault, appropriate penalties can be imposed on him. Well, if the machines were bought illegally, then to whom are the claims?

[carbofo]

alex0000 If Rogozin says this, then the facts have taken place.
Already repeatedly, such facts come out, here and there, it is very serious, in America for several hours the light was cut off what started there, and bran for several days?.
There will be nothing to eat in the city in a week, without electricity.
What about water? to draw a lot of water in Moscow? they will drink the river in a week.
and so on and so forth.

[Monster_Fat]

Yes, there our people tried to crank up the purchase of machine tools on the same principle as once upon a time when the "Soviets" bought machines at the "To-Si-Ba-Kikai" (known to us as "Toshiba") for processing submarine shafts. They were purchased on condition not to be used in the defense industry. And they did not take into account that now it is in the yard, after all, - the XXI century - everything can be traced and removed from action remotely.

[carbofo]

Yes, yes, it was at the exhibition in Zhukovsky, I remembered.
So about the air defense system it was said somewhere else, I don’t remember already.

[studentmati]

Quote: Monster_Fat

This is not a matter of one year.

I’ll support you, Brother, and I’ll say more - not for a year, but for two or three decades ....

[mountain]

Well storytellers that article that comments. At first, even this level was read and preparation, many world science fiction writers just have to rest. Pluses came across the sea for the artistic and technical nuances. But unfortunately they have nothing to do with reality or fortunately. )))))

[qwert1707]

Patients of various institutions and not that can sprinkle ... when the computer comes to hand

[poquello]

Quote: mountain

Well storytellers that article that comments. At first, even this level was read and preparation, many world science fiction writers just have to rest. Pluses came across the sea for the artistic and technical nuances. But unfortunately they have nothing to do with reality or fortunately. )))))

Unfortunately, they are related to reality, but I could not bear to read the article about inverters-converters to the end.

[ZenkyOkuShu]

As a person who has been engaged in vibration diagnostics for more than 10 years, I respond to science fiction about the Sayano-Shushenskaya hydroelectric power station.
The unit was destroyed due to the fact that it was deliberately left to operate at a critical frequency, for "economic reasons" "effective managers with economists' dipoles", and the technicians were told to shut up because they did not understand anything about it and mask the signal of the vibration control system.
This case was analyzed more than once at the annual qualification confirmation courses, which I constantly have to go through, analyzing the schedule of this generator during pre-emergency hours.
So they ruined many power systems in the territory of the former USSR. No economist was hurt unfortunately.

[carbofo]

Well, formally this is a diversion and so and so, the techies knew that this would end.
So the author’s calculations do not contradict what you described, just the motives are different.

[qwert1707]

Question to the author of the article, which physicist ..
DO YOU ANYWHERE HEAR ABOUT CAVITATION?
First, find out what it is, and then write about malicious viruses)))))

[Justme]

The discussion will matter if it is clarified - what type of bearings are there ..

I counted the natural shaft frequencies for our turbochargers - our operating speed range also included the first resonant frequency - due to damping, we could stand on it for an unlimited time ..

[voliador]

Interesting version.

[Asan Ata]

I think that the dry residue - the Internet - is contagious, and managing technological processes via the Internet is like giving a wife a vibrator with Internet access.

[SCHUZMAN]

Yesterday, communal workers did not sprinkle sand on the road, not otherwise the machinations of the State Department ...

[Flatter]

The increased vibration of the turbines leads to damage to the blade apparatus, which reduces the efficiency, bearings and very expensive repairs, but not to disasters. The mass of the blades is small compared to the mass of the turbines. They turned off the generator prematurely when stopped and the turbine was dispersed

[Jager]

I could not finish reading this gray nonsense to the end. The author may be the greatest programmer, but knows electrical engineering "at the high school level."
1. The voltage of the three-phase circuit is not 360, but 380 V.
2. It would be interesting to look at the remains of a conventional asynchronous, and even more so at its switching equipment, if the network frequency is reduced by at least 3, ie up to 47 hertz. Tested on my own experience.
3. It is necessary to have all the documentation for putting the equipment into unstable modes, and this is not one book and not one gigabyte of information, and in any case, part of the information will have to be "taken" in the form of logs. In addition, it is impossible to turn off emergency sensors and protection without using personnel, and in the case of a hydroelectric power station, half of the plant's employees.

[Jager]

The Chernobyl experience was safely forgotten. The emergency cooling of the reactor was turned off and it was brought into modes not regulated by the test program. At the hydroelectric power station - they scored on the vibration control system and the technical condition of the hydraulic units. NO ACCIDENTS JUST HAPPEN. Most often, this is a complex of quite obvious reasons for a fairly long period of time. The management of the hydroelectric power station knew about the sad state of the already not the most perfect hydroelectric unit, but did nothing in time. The blame for everything is sabotage in the brain - this is our eternal "maybe".