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Sulfuric Acid Trouble cases

1. SO3 white smoke jet accident

October 1992, from the factory length of the Malaysian company many years of relationship, we have received a sudden international telephone.
"Help, Ono san!"
At the time of re-start after the regular repair, and will start-up and operation of the sulfur while stopping the circulation pump of the absorption tower, a large amount of SO3 unabsorbed is ejected from the chimney, the adjacent competitors factory (for export flows into was a clothing manufacturer), a large number of employees, most of them fell a young woman is difficulty breathing, Toka he was a great uproar in the national news. Of course, sulfuric acid plant is shut down indefinitely.

Why? After absorption tower circulation pump has not stopped, it would not move combustion air blower? And when I heard the reason, "because the periodic maintenance that while releasing the interlock, had forgotten to return to the original" thing with.
It is a simple mistake To hear. However, the result is serious.
"From the DOE (Department of environment, Ministry of the Environment), until it receives a complete preventive measures are said not to resume operations, it can not be trusted even out the proposed measures, since you are an expert of the plant maker DOE and because also would be convinced, and I say that just to me to make the proposed measures to come. "
Director, because it was the president with even people missed, the next day to discuss the correspondence, it was that I'll go anyway.
With that as soon take the airplane ticket, I went to the local 3 days after the phone call.
Customer and consultation in the field, to make the idea of ​​"also came a large amount of SOx newly established capable of absorbing scrubber after absorption tower", PFD, Process description, Construction schedule other, it has created a DOE submitted documents in the field.
We came back in the stay of 10 days. In subsequent information, DOE is Toka he is convinced in my Report, who admitted operations resume. (When you think from now, you will of much use also Under the table)


Lessons learned: In developing countries, even in the safety device, because sometimes resulting in a start while the removed, by the going.
(Even if I say that, it takes the measures to the bottom and plant cost will be enormous, and this will become a competitive disadvantage. It is a place to some extent it may not forced referred to as a "no choice". Difficult)
 2. Impeller melts!

This is a construction completion and operation beginning of the trouble of sulfuric acid plant overseas.

Because the DC / DA method, drying tower, intermediate absorption tower, and the final absorption tower, but I tower are arranged 3 groups, among drying tower and the first absorption tower that, in particular impeller of drying tower of the pump, nearly 45 It is from being gone clean melt in the day.
Studio is a long-established chemical pump manufacturer in Japan, is particularly company in the circulation pump for the sulfuric acid, which boasts Japan's track record. The material of the impeller that has been used is one that manufacturers have been developed purposely as "a sulfate plant circulation pump", previously it is of being used more than two years at large facilities in Japan and overseas.
However, anyway it sends the spare parts, it is no longer is also melted, while repeating the feed for the next ... and gave a corrosion test of the pump impeller for material just to make sure the manufacturer's lab.
The result is over without a problem. Manufacturer name is "than there is this customer-specific special circumstances?".
Suddenly it Omoitachi, "there is a track record for more than two years," the place where I had taught a third of operating conditions that, either, exhaust gas of copper smelting was the raw material. However, the raw material of the plant that caused the trouble, is recovering molten sulfur from petroleum.
"Than sulfuric acid is too beautiful?"
"There is no such a thing, I just paid the same pump also in the country P, Inc."
P company, has to do with my company, also know well technician. the phone to talk I was at the circumstances "recently to think of it, since the current value of the pump motor is down, plan is to check with close temporary stop" is called.
Question to visit the open day, where I had to show an impeller, full of holes by corrosion, state that seen through the other side.
"It was dangerous!"

Manufacturer of salespeople, and cause differences of raw materials, it was admitted at last.
When sulfur is of raw materials, product sulfuric acid is a very clean, is enough to pass the purification of sulfuric acid standard. The stainless steel-based alloys, it is likely that corrosion resistance is imparted by the non-conductive film is formed on the surface by oxidizing ions in the sulfuric acid, but this non-conductive film produced in (very little of the impurities) sulfuric acid clean It will be considered are not. (Smelting gas sulfuric acid, is considered a NOx generated in trace amounts of dust and electrostatic precipitator pole becomes the oxidizing ions)

Trouble is, no longer keep up with the supply to the exchange of frequent spare impeller manufacturer, place that supplied the impeller "for dilute sulfuric acid" with the intention of "band-aid", it can be seen that this is long-lasting, it has been resolved at last. It was a great achievement of the injury.

Lessons learned:
1. "Examples of other companies" is not necessarily true for the corrosion of sulfuric acid.
2. "Clean sulfuric acid" is, in the stainless steel-based material is corrosive.
 3. Unexpected unexpected to " sulfur by-product of "

This is a by-product from the coke oven gas of certain steel mills of China, is the trouble with sulfuric acid plant as a raw material to sour gas that contains H2S.

In addition to the H2S in the sour gas, CH4, C2H6, C6H6, CS2, contains miscellaneous gas of ammonia ... and so on. By burning them in a furnace SO2, H2O, cooled to from the CO2, N2, and sends it after the wet dust collector into the drying tower.
Equipment of commissioning is also complete, it is plant start finally.
The flowing air, and ignited in sour gas, but was gradually ... will Yuku raise the combustion furnace exit gas temperature by adjusting the gas / air ratio, does not increase the gas temperature is quite. SO2 concentration also remains low. In was considered "because the amount of air is too much for the amount of gas, combustion gas temperature does not rise is dilution", I was squeezing the air. However, the temperature also SO2 concentration does not increase. I Yuki down rather.
"Do sour gas concentration is low for?" "Whether nitrogen is too much?"
Etc., and examine various but I do not know. In the meantime, the site received a report with the "cooling tower circulating liquid is cloudy" from engineers who had been patrol, and I come to the site.
Certainly, it has liquid is cloudy. What would? And, when you look good well, it looks fine particles of sulfur.
I noticed the "Oh!".
The combustion furnace exit gas temperature does not increase, not because the air is too much, it was because air rather was insufficient. Therefore, look combustion H2S gas is conducted to the cooling tower, where Claus reaction 2H2S + SO2 → 3S + 2H2O
The causes, are you sulfur is deposited.
(Flow meters of sour gas and air had been attached, because the composition of the gas is uncertain, accurate flow rate ratio of the raw material gas and air do not know)
Immediately stop the operation, and inspect, by-product sulfur, past the cooling tower, has been deposited on the collecting electrode of mist Cottrell, the electrode plate was covered in thick sulfur of smack yellow .
Then round three days, still cold Shanghai of March, we clean the Cottrell inside of sulfur using the water in the colleagues and two people.
I was was before delivery of the plant, Chinese and Japan of the original 請会 company also chilly as the "idea of ​​you mistake", I did not get to help out at all.

As lessons learned from this accident, in subsequent similar sulfuric acid plant, gas analyzer after leaving the furnace, it was decided to also be sure to install O2 gauge not only the SO2 meter. If the attached O2 meter, it is "O2 = 0%" or "air is not enough!" And because it should have found immediately.
4. Carbon steel cooling tower parts of the delivery time

In the country of new equipment, raw material gas includes a halogen, it was decided to use a Teflon impregnated carbon steel superficial to the first gas cooling tower.
From performance and price, but I decided to import the made in France, after the arrival in Japan, and received contact from the Japanese branch of manufacturers and "has cracked the gas inlet nozzle".
Of course, we should not and not replaced. If you say case replacement immediately, "We said that it take five months," the manufacturer says with.
Not a joke, there are only three months until the operation of the equipment. "Is it not somehow in a month?" "Try Kakea~tsu and France"
Since the branch office of humans are Japanese, (because it is France 8 hours late, night) in the early morning every day and will demand the payment by phone to the local factory addressed, Lachi does not fall.
From the customer, "You, Once hit the ass in Tomarikon to the manufacturer's factory?" But was told and the sarcasm, just immediately after the 9.11 terrorist attacks, overseas business trip the era of self-restraint. It does not take.
"Because pay three times the nozzle price, is not you? Expedited delivery" was also offer a.
To them "from the local plant manager," the employee had a contact with the "no longer stomach 2 months near at all vacation. Even got much money, you can not work if there are no employees"
I'll say that. You see, vacation! Vacation is a top priority of the French. Japanese would Komaro, but bankruptcy used by Americans anyway.
I've decided to prepared to pay the penalty, a blessing in disguise, if trouble occurs in the construction of the upstream of the desulfurization equipment, the construction period was delayed more than six months. Thanks, we have achieved somehow exchange of nozzle before commissioning.
It was a good study. Later, I "made in France of the machine, only buy Na when a delivery room," the men had commanded. Come to think of it, there was a local trading company of the president of Malaysia of the relationship a long time ago, "I am, no matter how you do not buy is made in France and the Italian-made products even cheaper," he had said. The reason is, that the delivery time of the because bullshit. America is also quite irresponsible, United Kingdom Well Well, can most credit or "but Japan and Germany."
After a great deal, we have imported a special machine from France for the plant of pharmaceutical products. Because it was customer's specified by the manufacturer. But this is totally no problem. By companies that are in the Alsace region, it is a Germany-based and from the name. Alsace is historically land that France and Germany have been repeating the territorial dispute. I was thinking like "kana because that contains the blood of the Germans."
5. Chemical injury accident
Concentrated sulfuric acid, and damage to the human body, can cause severe burns. After healing also, it will remain ugly keloid-like traces.
Also my body, the side of the upper arm and the navel, there are burn marks. Both, is the wounds received in Nigeria.
This such as lighter, my cousin when I was a junior high school student, was killed instantly in an accident that wear a sulfuric acid from the head. In Bangladesh, my place of work to be in operation guidance, tank exploded in a welding spark, local people 5 people was also an accident that death.
In Nigeria, also one of the bank's Japanese supervisor was injured quite a large amount, it has been forced to hospital for a while. This is, if you are working to remove the piping of sulfuric acid together with local people, to have still contains sulfuric acid inside by mistake as "empty", with sulfuric acid which is blowing in order to loosen the bolts of the flange It is the thing which was injured. Moreover, "the flange bolts, be loosened from the opposite side of the body," "Even in the sky, in going in that are filled sulfuric acid inside" that, did not observe that you are taught in safety education .
Concentrated sulfuric acid, because it itself is dangerous, equipment it should be structure and material that does not go out and leak easily. In the past, it did not get in quite such measures for economic reasons, because the current to enter the equipment is hand inexpensive of good material, it is safe when compared to the old days.
To prevent the accident? Over facilities, it should be all "Fool-proof". This is a good word, "fool even okay", in other words, so as not to cause an accident even if the erroneous operation, or it is to design the equipment so that not occur erroneous operation.
From behavioral, it is never "that you do not neglect the principle." Also in the above Nigeria of accident, that it had ignored the note and procedures that are taught in safety education was the cause of the accident.
Eteshite human beings, is what they want to omit the procedure according to get used to. If you have cut corners to say is "troublesome because," "since the accident until now has not happened once," accident only when such is the one that occurs.
And, for the time that had happened Should acid leakage, it is to keep the proper protective equipment and sufficient number secure.
Everyone, is a matter of course. Yes, accidents happen because not doing commonplace things commonplace. When the nuclear accident in Fukushima, and never will be so much serious and did not imagine. Since TEPCO is a leading company, because I thought that the safety procedures also training also be sufficiently.
However, even pump that cools the ② furnace did not imagine tsunami of ①20m, is located in the place also power supply is low, has become unusable everyone in the tsunami (backup was not secured in a safe place) ③ " etc. of blunder corresponding manual was not about the situation in which cooling water is stopped Maru "in the tsunami is now clearly one after another. Large companies also do not take credit.
Everyone, in the accident, to a painful eye is yours. Please do not compromise in regard safety.
6. " developing countries work in. "

Domestic as well, and it has worked in the "developing countries" overseas.
The secret to achieve the work vigorously? → is "patience". Never angry Do not be. Here's not in Japan, because the opponent's not a Japanese. (In other words, "common sense" of Japan, in developing countries's the "insane")
In Malaysia, concrete sulfur pits, underground water has been entering the molten sulfur from the beginning full of cracks. Since the temperature of sulfur is also 150 ℃, of course water boils, it becomes steam. and "It's a hot spring, like," I was laughing with.
It is because you are using a "cold a minus to cement" = moisture absorption to defective cement that became bad of coagulation. We want to focus on cost than quality. Cheap thing only is not ready, after the "on-site white somehow."
And I did not want Yari because the corrosion, but we cover all of the inner surface of the concrete layer in steel plate. And then, now Rashiku sloppy welding, steam has spouting along the weld line.
After I complain to the contractor, "In so cheap contract, very welder and I do not hire something of qualified personnel" We Usobui with.
The fact that? I'm allowed to welding work on amateur unqualified!
Local construction work is the customer's jurisdiction. Apparently, construction managers of the customer are, they apparently have put bosom by kickback the contract money. But when you hear, in Malaysia it Toka's what "the scope of common sense."
This, rampant of kickback or bribe, so common in developing countries. In Nigeria, it was called a "dash" to a bribe to pass to the police officers and officials. Even doodling To when to end whether bureaucracy you do not know, dash if I get even gold, or What a sense that it is sudden acceleration?
Poor maintenance of infrastructure is also common.
In Nigeria, anyway power failure occurs frequently, but was also construction commissioning was hard.
Sulfuric acid facilities, I have a need to keep the preheat the converter and the combustion furnace before the start, this will take about 48 hours. Summary of the sudden if you are willing Na temperature has been rising, and "power failure". Temperature of the converter is lowered, electricity is the place came also temperature increase start, repetition of ... down is also "a power outage!" And the temperature after a while.
The most frequent record, 35 times a power failure in one month. Indeed, the last became the mental state of "Kamidanomi".
Poor quality of "Made in local".
Steel pipe for boiler, to buy is called in the Japanese JIS and steel pipe which corresponds to the STB (Made in India) has been assembling a hot air dryer. Once I started to completion after water pressure test, and I still break in the longitudinal and "bread", "bread" from among you do not reach the default pressure! Apparently, it seemed to contain impurities in the drawing direction. Hurriedly and imported from Japan, I've not managed to meet the deadline to complete, it is ridiculous deficit.
7. Of gas heat exchanger high temperature corrosion
Complaints came from customers.
"Recently, the whole of the ventilation resistance increases, it does not flow as I think the gas, production volume is down."
A.
When you take a look, there is a large resistance to the shell side of the hot gas heat exchange of carbon steel (receive the gas from the converter first layer to the tube side).
At the time of periodic repair, if you saw it cut open the shell, has a whopping internal tightly packed with a thin film of iron oxide, flaky debris that it is broken.
Thin film, have overlapped in many layers round the outside of the tube, like "Baumkuchen". At a glance, it found an oxidation product tube has high-temperature oxidation.
Indeed, since the gas temperature from the first layer converter is about 600 ℃, carbon steel will be high-temperature oxidation. Such oxidation products are also not uncommon. However, it is amazing the amount. It does not stand still only construction after eight years.
We've heard your operations situation from the customer, here Toka he frequency of stop-start many, deliberate long-term stop five times a year by the production plan.
I found in it. On the surface of the long carbon steel exposed to high temperatures, of course oxidation products occurs. When you stop the plant decreases the temperature of the heat exchanger, the steel portion of the tube is then deflated, the portion of the oxide from the shrinkage rate is small steel, it will peel off from the surface. Usually, this "generation and cooling peeling" includes, but is should not only occur during the annual periodic maintenance, it is 5 times a year here, that is five times faster generation of standard amenities. In other words, the eight years of this equipment will mean that hits 40 years of ordinary equipment.
Eventually, it was replaced with a new heat exchanger that was all the tube SUS304. After that, our opinion, gas heat exchanger in a small equipment has changed the design criteria to be from the beginning made of SUS304.
And this customer, but there was one quarrel and around the expense of the heat exchanger update, it is omitted.
8. Acid circulation piping corrosion of
In new sulfuric acid plant, as the material of the circulation pipe of drying tower, absorption tower, it was specified the use of SUS316. Since the customer's is a company that has been involved in stainless steel production, and Toka I want to contribute to the consumption of stainless steel, even a little.
However, operations start early, corrosion accident of the piping was frequent.
Elbow, cheese, such as downstream of the valve, it is remarkable to place, especially caused turbulence in the liquid.
Stainless steel, if the room temperature or less can be used in the long-term in SUS316, but does not recommend using it in place of more than 70 ℃ as the circulation pipe. For each impurity other factors in sulfuric acid, because there is otherwise with the case of long-lasting.
Actually this equipment, was in charge of the senior rather than me. SUS316 Once I heard the reason for the use, things and because it was specified customers as described above.
Most of the piping it was exchanged in Teflon lining pipe after all. From the customer, not issued gold because the responsibility of all us, and it has been told.
and "you, but, was the specified material of'm your" When you argue with, "When your company that would be a professional company? we are wrong, the duty should be there to point out that" the logic of the .
This is a fairly rough logic. Legal I do not know whether to but, but there is no not have such a feeling somehow.
"Failure both if unfortunate. If the expert, and useless compromise in technology surface"
It is a lesson that.
9. " Experts do not believe. "

The tight is the words, but in particular young people, "" blind faith "absolutely useless" I want you to remember in the sense that.
It is not directly related to sulfuric acid technology, but young, and there was that it tried to improve the facilities to get the SO3 by distillation of fuming sulfuric acid.
Because what kind of material was good or unknown, prepare a variety of test piece, put in the existing facilities, we have the corrosion test.
A result that was taken out after a certain period of time, violently corrosion as "higher material" at the time, towards the banal material is that the small amount of corrosion, it was what is contrary to "common sense" at the time.
I asked to visit us in the material manufacturer's Technical Director (Dr.), and sought an opinion on this result. This person, at the time was famous in Japan as a leading expert in the knowledge of metal material for sulfuric acid.
His view "this result is weird. I wonder how the test was bad. I would recommend this kind of Conditions if material XXXX" thing.
In his Suggested materials, where it drove by design and manufacture this equipment, the equipment in about two months corrosion can damage, it became the driving stop.
Again, where it was again the material test by installing a dedicated test equipment, it became almost the same result as the first test.
Even if there is fame of how much "guru", it was learned and it is important to believe the facts as facts.

Another is relatively recent, from I become officers.
In desulfurization of coke oven gas, facilities that my subordinates was in charge, all without put out the performance, now end up recreating some last line that was struggling. At the same time relationship that had received an order for more than one facility, it measures cost also became huge.
The reason for this was issued from the manufacturer of the oxidation apparatus of the circulating fluid for the "expected performance", and that in and is a "specialized manufacturer", "there are a large number of achievements", the person in charge was this even got to "swallow It was "thing.
However (it is that it was found later, but), because actual results up to now, even though height and circulating liquid composition and other conditions of the tower did different things fundamentally and this time, without having to pre-verification there it was that it had to blind faith to "study results of experts".

I will Yes "expert". However, he is not a God. It is to know knowledge is limited.
So I, for the customers when the technical advice "as above, but I think, whether or not adopted, please judge your company's responsibility" we have always said.
10. Impatient Na-Na get angry, give up
I have to work with quite long China local.
Initially, this word that was to ask from the direction of the local representative of the trading company. It seems to knowledge of business in China.
until the promised deadline to answer is no. Or it brings up again the conclusion of the previous meeting. Come was unabashedly a request not in the contract. How thought to stick to common sense out of the theory to the ...
And, here we are a few people, over there in the 10 times the number of people, you have been bubbling over unanimously.
In Shanghai Baoshan steel plant project, the construction period up to completion after receipt of order in the first place was 4 years 6 months. Was told to complain and "yeah! So if I do not I get a acceptance nearly five years even if the delivery?" From equipment manufacturers. From the instrument manufacturers "When you start the more, this time ordering our instrument was probably all specifications are revised, can not by the delivery of the same thing." It was also said to be.
And, impossible to achieve inspection criteria one after another.
"China-made equipment, the Well of you? Irassharu made in so strict standards, and import I want to," To tell you the irony and, undertone, in spear, and it while it says "I can not be in China."
Even if their own is possible, but I do it to the Japanese.
Because say that too insane, "such claims, I will not deviate from the common sense of the world" When chide with, "Ono teacher, Japan has a population of 130 million people. We Chinese are 1.3 billion people. Our people would be common sense of the world, "he said. No early, it does not come true.
Still, I, than the Japanese colleague who accompanied were, did not feel uncomfortable too strongly. Maybe, "to say only this, Chants I wish I wonder there is a reason" and, what because you have respect for the other party in its own way.
Even so, when you show off to juniors who are involved in business in China for more than experience in active duty, that of the "now is also true."
Will the "Chinese funny"? No, no, if you think it is now close to the position of third party, too homogeneous, be that those of Japanese society of "supposed to be seen not say" is heterogeneous in the world. In that sense, "more of us the world of common sense," it was Kyoben Shanghai technicians of words, might was right.
11. There is no money from?
1990, we have come to the sulfuric acid plant commissioning of Panzhihua steel plant of the mountains of Sichuan.
We are making the sulfuric acid from the secondary raw sour gas at the time of desulfurization coke oven gas.
Our basic design and supply of some know-how equipment, in charge of commissioning the company detailed design of Germany, the Chinese side was the charge of the construction and supply equipment.
From the Chinese side "of the blower capacity There are three times the required amount, what? What should I do when" It was asked. "Since the budget is tight," and Toka he has been looking for second-hand goods.
"From the blower outlet, please add the circulating gas piping back to the drying tower" I have been advised. Because too raise the gas temperature in many so recycling, it is dangerous if you do not cooling.
However flowmeter of the process gas because that is attached to the outlet of the drying tower, is also required flowmeter to recycling line. Than that "money to buy a flow meter is ...", I was raised doing in the service until the orifice of the design. Install the differential pressure gauge of visual, we were working to flow.
Chinese-made liquid level gauge attached to the pump tank of the absorption tower is also broken again and again. The wetted parts and Toka's are using a diaphragm of SUS316.
When you advice as "should I frog Hastelloy-C", as the "if made in China, you can buy five or more made in Japan one minute", "China is not made in", "please buy from Japan", to say The did not hear.
Then, in Shanghai of sulfuric acid equipment, orders the work to switch the thing was pyrite raw material sulfur raw materials, after four years of completion, was visited in aftercare at the request from the customer. It is that of 2000.
This seat was asked "because blower capacity is excessive you want to an inverter motor. Is it true, but say that it pays for itself in one year?". While I think that I wish not to change much, "Better yet, please had made the blower" You have advised, and whether you run ...
Eteshite in developing countries, say that "in the next few years will rise to profit" will not be welcome. Since we are replaced by more and more To leave the company, by the time you make a profit because his is not. Private companies and foreign is to same is true in China, because I want state-owned enterprises is also quite personnel changes, you will of similar. In other words, to raise the short-term performance, "to keep the current investment" it is's the best.
"Because there is no money" ... really, "I do not want to lower performance."
Of travelers from China of this year's Spring Festival, "爆買 physician", Is there in the place where it is.
12. Black out (power outage)
As I wrote, even "work in developing countries", in the work in developing countries, infrastructure is different is very difficulty in whether or not been established. And do you say, but such infrastructure is what "still developing" So, "developing countries". Many and will be in direct problem the most, it is a power outage. The commissioning of Nigeria of sulfuric acid equipment, there was 35 times of power outage in January. It is preheated, barely power failure If you think the temperature went up. Barely been started, and ignited sulfur power failure If you think ... that began to be sulfuric acid. In addition, the troubled, it the prospect of recovery do not know. Because you repeat too, it has increasingly young I also become pessimistic. In Malaysia, construction initially at (1985) point, there was occasional power outage. However, in the current 30 years, it is that of the no it as good go at all To. Again, it's neat development. Young people, the electricity will be folded anywhere, anytime I think something in common. But, even in Japan, I have (which is before from now 60 years!) Childhood in, because the power failure was not uncommon, it was what had been equipped with a sure candles in the house. Come to think of it, the essentials candle in each house as well in Nigeria. Night, becomes a power outage in the middle of it is a mah-jong in Japanese to each other that had been dispatched in commissioning, and make a candle to the four corners of the table, we also can do as "Qi", "Pong" in the dark. When the electricity is restored see each other's face, it had become completely black with soot. It called Black out in English that of a power failure. Since the lighting of emergency is also small, and will meet in a power outage the night in developing countries, you really will experience the "jet-black darkness." Scary thing.

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LEKULE TV EDITORIALS ARTICLES DC ROBOTICS DIGITAL SEMICONDUCTORS GENERATOR AC EXPERIMENTS MANUFACTURING-ENGINEERING REFERENCE FUNDAMENTAL OF ELECTRICITY ELECTRONICS ELECTRICAL ENGINEER MEASUREMENT TRANSDUCER & SENSOR VIDEO ARDUINO RENEWABLE ENERGY AUTOMOBILE TEARDOWN SYNCHRONOUS GENERATOR DIGITAL ELECTRONICS ELECTRICAL DISTRIBUTION CABLES AUTOMOTIVE MICROCONTROLLER SOLAR PROTECTION DIODE AND CIRCUITS BASIC ELECTRICAL ELECTRONICS MOTOR SWITCHES CIRCUIT BREAKERS CIRCUITS THEORY PANEL BUILDING ELECTRONICS DEVICES MIRACLES SWITCHGEAR ANALOG MOBILE DEVICES WEARABLES CAMERA TECHNOLOGY COMMUNICATION GENERATION BATTERIES FREE CIRCUITS INDUSTRIAL AUTOMATION SPECIAL MACHINES ELECTRICAL SAFETY ENERGY EFFIDIENCY-BUILDING DRONE CONTROL SYSTEM NUCLEAR ENERGY SMATRPHONE FILTER`S POWER BIOGAS BELT CONVEYOR MATERIAL HANDLING RELAY ELECTRICAL INSTRUMENTS ENERGY SOURCE PLC`S TRANSFORMER AC CIRCUITS CIRCUIT SCHEMATIC SYMBOLS DDISCRETE SEMICONDUCTOR CIRCUITS WIND POWER C.B DEVICES DC CIRCUITS DIODES AND RECTIFIERS FUSE SPECIAL TRANSFORMER THERMAL POWER PLANT CELL CHEMISTRY EARTHING SYSTEM ELECTRIC LAMP FUNDAMENTAL OF ELECTRICITY 2 BIPOLAR JUNCTION TRANSISTOR 555 TIMER CIRCUITS AUTOCAD BLUETOOTH C PROGRAMMING HOME AUTOMATION HYDRO POWER LOGIC GATES OPERATIONAL AMPLIFIER`S SOLID-STATE DEVICE THEORRY COMPUTER DEFECE & MILITARY FLUORESCENT LAMP INDUSTRIAL ROBOTICS ANDROID ELECTRICAL DRIVES GROUNDING SYSTEM CALCULUS REFERENCE DC METERING CIRCUITS DC NETWORK ANALYSIS ELECTRICAL SAFETY TIPS ELECTRICIAN SCHOOL ELECTRON TUBES FUNDAMENTAL OF ELECTRICITY 1 INDUCTION MACHINES INSULATIONS USB ALGEBRA REFERENCE HMI[Human Interface Machines] INDUCTION MOTOR KARNAUGH MAPPING USEUL EQUIATIONS AND CONVERSION FACTOR ANALOG INTEGRATED CIRCUITS BASIC CONCEPTS AND TEST EQUIPMENTS DIGITAL COMMUNICATION DIGITAL-ANALOG CONVERSION ELECTRICAL SOFTWARE GAS TURBINE ILLUMINATION OHM`S LAW POWER ELECTRONICS THYRISTOR BOOLEAN ALGEBRA DIGITAL INTEGRATED CIRCUITS FUNDAMENTAL OF ELECTRICITY 3 PHYSICS OF CONDUCTORS AND INSULATORS SPECIAL MOTOR STEAM POWER PLANTS TESTING TRANSMISION LINE C-BISCUIT CAPACITORS COMBINATION LOGIC FUNCTION COMPLEX NUMBERS CONTROL MOTION ELECTRICAL LAWS INVERTER LADDER DIAGRAM MULTIVIBRATORS RC AND L/R TIME CONSTANTS SCADA SERIES AND PARALLEL CIRCUITS USING THE SPICE CIRCUIT SIMULATION PROGRAM AMPLIFIERS AND ACTIVE DEVICES APPS & SOFTWARE BASIC CONCEPTS OF ELECTRICITY CONDUCTOR AND INSULATORS TABLES CONDUITS FITTING AND SUPPORTS ELECTRICAL INSTRUMENTATION SIGNALS ELECTRICAL TOOLS INDUCTORS LiDAR MAGNETISM AND ELECTROMAGNETISM PLYPHASE AC CIRCUITS RECLOSER SAFE LIVING WITH GAS AND LPG SAFETY CLOTHING STEPPER MOTOR SYNCHRONOUS MOTOR AC METRING CIRCUITS BECOME AN ELECTRICIAN BINARY ARITHMETIC BUSHING DIGITAL STORAGE MEMROY ELECTRICIAN JOBS HEAT ENGINES HOME THEATER INPECTIONS LIGHT SABER MOSFET NUMERATION SYSTEM POWER FACTORS REACTANCE AND IMPEDANCE INDUCTIVE RECTIFIER AND CONVERTERS RESONANCE SCIENTIFIC NOTATION AND METRIC PREFIXES SULFURIC ACID TROUBLESHOOTING TROUBLESHOOTING-THEORY & PRACTICE 12C BUS APPLE BATTERIES AND POWER SYSTEMS DC MOTOR DRIVES ELECTROMECHANICAL RELAYS ENERGY EFFICIENCY-LIGHT INDUSTRIAL SAFETY EQUIPMENTS MEGGER MXED-FREQUENCY AC SIGNALS PRINCIPLE OF DIGITAL COMPUTING QUESTIONS REACTANCE AND IMPEDANCE-CAPATIVE SEQUENTIAL CIRCUITS SERRIES-PARALLEL COMBINATION CIRCUITS SHIFT REGISTERS WIRELESS BUILDING SERVICES COMPRESSOR CRANES DIVIDER CIRCUIT AND KIRCHHOFF`S LAW ELECTRICAL DISTRIBUTION EQUIPMENTS 1 ELECTRICAL DISTRIBUTION EQUIPMENTS B ELECTRICAL TOOL KIT ELECTRICIAN JOB DESCRIPTION INDUSTRIAL DRIVES LAPTOP SCIENCE THERMOCOUPLE TRIGONOMENTRY REFERENCE UART oscilloscope BIOMASS CONTACTOR ELECTRIC ILLUMINATION ELECTRICAL SAFETY TRAINING ELECTROMECHANICAL FEATURED FILTER DESIGN HARDWARE JUNCTION FIELD-EFFECT TRANSISTORS NASA NUCLEAR POWER VALVE COLOR CODES ELECTRIC TRACTION FLEXIBLE ELECTRONICS FLUKE GEARMOTORS INTRODUCTION LASSER PID PUMP SEAL ELECTRICIAN CAREER ELECTRICITY SUPPLY AND DISTRIBUTION MUSIC NEUTRAL PERIODIC TABLES OF THE ELEMENTS POLYPHASE AC CIRCUITS PROJECTS REATORS SATELLITE STAR DELTA VIBRATION WATERPROOF