AC vs DC @Ohm – Eclectic Electricty A Summary of Man’s Tricky Power at Its Best www.shishi.ng

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Ohm’s Law is V = IR, where V = voltage, I = current, and R = resistance.

 

At Home  in our Offices Schools Outdoors even ourr Bodies  Ohms Law is always at work

Every appliance that has battery as energy storage uses DC current for charging.

Usually, adapter has circuit that converts AC mains voltage into DC & that acts as input to your laptop’s battery.

So, adapter draws AC from supply, but battery charges on DC.

 

and make a note that every device which is using an battery is always charged through DC beacuse still there is no device or equipment which stores the AC current directly.

Hence, it is clear that first we have to convert that available AC current into DC current and then fed to the laptop’s battery.

Firstly I have never heard of DC Lightning Meaning God has a soft spot for AC but Electiricty is in our Bodies and thnkfully it is NOT DC

A power inverter, inverter or invertor is a power electronic device or circuitry that changes direct current to alternating current. The resulting AC frequency obtained depends on the particular device employed

 

 

 

 

AC Vs DC

*Amount of energy that can be carried:

AC-Safe to transfer over longer city distances and can provide more power.

DC-Voltage of DC cannot travel very far until it begins to lose energy.

*Cause of the direction of flow of electrons

AC-Rotating magnet along the wire.

DC-Steady magnetism along the wire.

*Frequency :

AC-The frequency of alternating current is 50Hz or 60Hz depending upon the country.

DC-The frequency of direct current is zero.

*Direction :

AC-It reverses its direction while flowing in a circuit.

DC-It flows in one direction in the circuit.

*Current :

AC-It is the current of magnitude varying with time

DC-It is the current of constant magnitude.

*Flow of Electrons :

AC-Electrons keep switching directions – forward and backward.

DC-Electrons move steadily in one direction or ‘forward’.

*Obtained from :

AC-A.C Generator and mains.

DC-Cell or Battery.

*Passive Parameters :

AC-Impedance.

DC-Resistance only

*Power Factor :

AC-Lies between 0 & 1.

DC-it is always 1.

*Types :

AC-Sinusoidal, Trapezoidal, Triangular, Square.

DC-Pure and pulsating.

 

Experiments in Killing Animals by the Alternating Current, as Conducted in the Edison Laboratory at Orange, N. J.

Nikola Tesla, the inventor of 3-phase AC current, ironically once worked for Edison. All the while, Tesla ached to tell Edison about his AC induction motor. Tesla knew that Edison didn’t think much of alternating current.

It was all nonsense, Edison said, an unproven and unreliable system favored by Europeans who didn’t know the first thing about electricity. But Tesla held out hope that Edison would see the beauty of the induction motor’s simple design and overcome his prejudice against alternatives to his DC system. Tesla finally worked up the nerve to approach Edison about the induction motor when the two men were at Coney Island in late 1884.

“The moment that I was waiting for was propitious,” Tesla recalled. “I was just about to speak when a horrible looking tramp took hold of Edison and drew him away, preventing me from carrying out my intention.”

The story is just odd enough to be true. Or perhaps Tesla never worked up the courage to approach Edison. Or if he did, Edison rejected the idea out of hand. After all, Tesla’s motor wasn’t an improvement to the DC system; in many ways it was a repudiation of it. The two electrical systems were completely incompatible; a motor could be built to run on AC or DC, but not both.

In any event, Tesla quit the Edison Works in spring 1885. Tesla simply didn’t fit. Tesla and Edison were far too different to strike up a working partnership.

Tesla Meets Westinghouse; DC Transmission Dies A Slow Death

Both men were geniuses in their own way, but Edison’s was 99 percent perspiration, Tesla’s 99 percent inspiration. The two men would rarely cross paths again, but their inventions would soon clash openly in the marketplace.

Tesla initially floundered after quitting Edison. He took a job as a ditch digger for a while, and would later recall this period with considerable embarrassment. Gradually, Tesla found his footing and began to shop his induction motor idea to potential investors.

That’s how he met George Westinghouse.

George Westinghouse was a Pittsburgh-based inventor and industrialist famous for devising the railroad air brake, a safety device that saved countless lives. Westinghouse was a bear of a man, a large-framed figure with a walrus mustache, genial manner, and the sort of stoutly reliable face you’d see on a box of cough drops.

Born in 1846, a year before Edison, Westinghouse was raised in an atmosphere of invention. His father had a bustling farm machinery shop and was awarded seven patents for threshing and sawing machines. Young George learned to read blueprints at an early age and began to sketch his own designs.

At seventeen, Westinghouse ran off to join the Union Army in the Civil War. He eventually transferred to the Navy and worked as an engineer on two steam-powered battleships. After the war, Westinghouse turned to invention full time and was awarded his first patent in 1865 for a rotary steam engine. He had just turned nineteen.

Three years later, Westinghouse came up with what would be his most famous invention, the railroad air brake. It was built on the idea of applying braking to all wheels of railroad cars by means of compressed air driven by a steam pump. Westinghouse’s air brake system transformed the railroad industry, significantly reducing accidents.

Westinghouse eventually became a world-class inventor in his own right, credited with nearly four hundred patents.

In the early 1880s, Westinghouse began to turn his attention to electricity. Westinghouse had been one of thousands of spectators at Edison’s Menlo Park lab when the Wizard first demonstrated his incandescent lamp. Electricity had always been technically interesting to Westinghouse; with the success of the Edison system, it now seemed potentially profitable. In December 1885, Westinghouse joined with his brother and a handful of other backers to form the Westinghouse Electric Company, with capital stock of $1 million. The main assets of the company were twenty-seven patents relating to electricity that Westinghouse had bought up.

Most of the patents purchased by Westinghouse were for direct current lighting and power systems. The designs were similar to the Edison system but just different enough to avoid obvious patent infringement.

The DC market was tough to crack, though. The Edison companies dominated the industry; customers knew and trusted the Edison name. Edison controlled all the best patents on DC lamps, dynamos, and motors, and his company became increasingly aggressive about filing lawsuits against suspected patent infringers.

With Edison’s near-monopoly of the DC market, Westinghouse turned his sights to the new technology emerging in Europe: alternating current. AC transmission was largely unproven, but it had some interesting qualities that allowed it to outperform DC in certain situations.

One of DC’s biggest shortcomings was that it couldn’t be transmitted much more than a mile from the central station without significantly losing power. Edison’s Pearl Street station barely served half a square mile of New York; dozens of stations would have to be built to serve the entire city, and real estate was expensive in New York. Sparsely populated areas might never be electrified, since no company was going to build a DC power plant to serve a handful of people.

Alternating current, on the other hand, could be made to travel farther, thanks in part to the transformer. With the transformer, alternating current could be easily increased or “stepped up” to a higher voltage, which could travel through wire more easily. Consequently, high-voltage AC could be transmitted longer distances along thinner, cheaper copper wire, with the voltage then “stepped down” for use in homes and offices.

There was no practical way to increase and decrease DC voltages. Direct current was best produced and transmitted at a low, constant current, 110–220 volts, and thus didn’t have AC’s built-in flexibility.

Westinghouse was intrigued by AC’s potential but was unsure whether it was reliable or cheap enough to rival DC. Articles in the electrical trade journals were regularly hostile to AC, dismissing it as an unnecessary and unworkable alternative, a laboratory trick best kept in the laboratory.

Persuaded that AC was worth a gamble, Westinghouse went out and bought the best AC patents he could find, the Gaulard-Gibbs system from Europe. It wasn’t a full alternating current system, but Gaulard-Gibbs had an essential piece: the transformer that stepped up and stepped down the line voltage, the key to AC’s cheap long-distance transmission. A version of the transformer was brought to Pittsburgh, and Westinghouse and his team of engineers set out to improve the design.

The market for alternating current, however, still faced a roadblock. Westinghouse was missing a crucial piece of a complete electrical system: a reliable motor that would run on AC. Nearly all the commercial motors made at the time ran on Edison’s DC system; it would have been foolish for manufacturers to make anything else.

The few alternating current motors available were markedly inferior; they couldn’t start by themselves and were prone to vibrate wildly once they were running.

Nikola Tesla, induction motor in hand, came along at just the right time for Westinghouse. Tesla had been shopping his induction motor for two years after leaving Edison, with no success. On May 1, 1888, he was awarded a series of patents, among them U.S. patent number 381,968 for an “Electro magnetic motor,” and patent number 382,280 for “Electrical Transmission of Power.” The latter patent detailed how alternating current could be used to drive the motor, what would become known as the “Tesla polyphase system.”

Around the same time, Tesla accepted a last-minute invitation to give a lecture on his work before the American Institute of Electrical Engineers at Columbia University. The lecture, titled “A New System of Alternating Current Motors and Transformers,” turned out to be a sensation. Tesla demonstrated two small induction motors and many of the academics in attendance reacted with astonishment and even a touch of chagrin. The induction motor was simplicity itself, rotating without any moving electrical contacts. It made DC motors look clunky by comparison. The lecture and demonstration established Tesla’s name in the scientific community practically overnight.

George Westinghouse contacted Tesla just days after his breakthrough lecture. Westinghouse knew that if the AC induction motor was everything Tesla said it was, it could be the reliable motor he had been looking for, the missing piece in his commercial AC system. After some negotiation, Westinghouse bought the rights to Tesla’s patents for $70,000 plus a royalty of $2.50 per horsepower for each Tesla motor. Once the deal was signed, Tesla moved to Pittsburgh and worked beside Westinghouse for nearly a year, adapting the Tesla motor to the Westinghouse system.

Edison viewed the Tesla-Westinghouse collaboration with mounting suspicion. The inventor had nothing against Tesla for selling his induction motor to Westinghouse. The AC motor, along with the entire alternating current system, Edison believed, was doomed to failure.

Edison went public with his opinion in a pamphlet published in 1886. “A WARNING FROM THE EDISON ELECTRIC LIGHT COMPANY,” the cover declared in blood-red lettering. The use of AC meant “greatly enhanced risks to life and property,” the pamphlet declared, cautioning that the cost of such damages would have to be borne by those who purchased a Westinghouse AC power plant. The brochure included several graphic newspaper accounts of accidental deaths at the hands of alternating current. In one, an electrical lineman was found grotesquely hanging by his neck in a nest of electrical wires sixty feet off the ground after having been dealt a fatal shock by a Westinghouse line. In another, a theater manager was struck dead on the stage in the middle of a Saturday matinee when he received a fatal shock of AC from a poorly insulated wire.

No such horrors occurred with DC systems, the Edison pamphlet assured consumers. In contrast to the “deadly” AC system, “we have the glorious record of the Edison low tension system, from which there has never been a single instance of loss of life from the current employed.” The brochure confidently predicted that the AC system “is not destined to assume any permanent position. It would be legislated out of existence in a very brief period even if it did not previously die a natural death.”

The shrillness of the attack revealed more than Edison intended—the challenge from AC had him spooked. Since the early days of Pearl Street, Edison had enjoyed a comfortable monopoly on electrical generation and distribution, and had seen small rivals come and go. But AC was different. It didn’t seek to improve upon Edison’s DC system; it aimed to usurp it. The Old Man never walked away from a fight, and this was shaping up to be a bareknuckle brawl.

Edison’s DC system still had more power plants, but the Westinghouse AC system was adding new plants at a faster rate. Edison was also being squeezed by a French syndicate that was cornering the market on copper, sending the already high price of copper soaring. The fact that high-voltage AC could be transmitted using thinner, cheaper wire made it even more attractive when copper prices spiked. Edison had fought off scores of competitors in his day, but the AC forces were proving to be formidable opponents.

Edison had no scientific evidence that AC was inherently more dangerous than DC, despite his company’s claims to the contrary. The anecdotal evidence from dozens of accidental electrical deaths suggested that either current could kill under the right circumstances. Higher voltages certainly posed a greater threat to life and limb, but DC-powered arc light systems had been using 3,000 volts for years without a word of protest from Edison. The Westinghouse AC system used at most 2,000 volts, and that was confined to street lines. The alternating current going into homes and offices wasstepped down to as little as 50 volts, while Edison’s DC system ran a 110-volt DC line into the home. Edison’s dire warnings about the dangers of AC were built more on fear than facts.

Edison agreeing to team up with the unscrupulous Harold Brown, a charlatan who had only a rudimentary knowledge of electricity and no formal training as an engineer, is a measure of how worried the inventor had become over AC’s steady inroads into his electrical distribution empire.

In early July 1888, the word went out on the streets of Orange that the Edison lab would pay 25 cents for every stray dog delivered to its door. Neighborhood boys led the roundup, and the lab soon had more than enough subjects for Brown’s experiments.

The experiments at the Edison lab began at ten o’clock on the evening of July 10, under the soft glow of the incandescent lamps that Edison had invented nearly a decade before. Brown had set up a portable dynamo capable of generating 1,500 volts attached to a pair of wires that would be attached to each dog’s legs. Brown detailed the proceedings in a lab notebook, setting down in dispassionate prose the torture and execution of living creatures in the name of science.

First Experiment

….grisly stuff…..

Second Experiment

….more grisly stuff…..

Third Experiment

….some more grisly stuff…..

Fourth Experiment

….awful, man. Truly awful………

Edison also must have known that Brown’s dog experiments were hardly scientific. There were no control subjects. The weight of each dog, a crucial factor in a creature’s resistance to electricity, was merely estimated. The St. Bernard puppy was subjected to multiple shocks of varying voltages of both DC and AC, making it impossible to single out a fatal blow. Neither dog in the experiment was dissected, leaving Brown free to interpret the results as he wished—as proof of AC’s singular deadliness.

George Westinghouse viewed Brown’s sensational claims about AC with growing dismay. Westinghouse was appalled most of all by the growing savagery of the AC/DC battle. “The struggle for the control of the electric light and power business has never been exceeded in bitterness by any of the historical commercial controversies of a former day,” Westinghouse wrote. Nonetheless, Westinghouse wasn’t so highminded that he refrained from taking a shot at the competition when he got a chance. “I have witnessed the roasting of a large piece of fresh beef by a direct continuous current of less than one hundred volts within two minutes,” Westinghouse wrote in a magazine article, adding that anyone touching a live 100-volt DC wire would find it “painful beyond endurance.”

He argued that Brown’s dog experiments didn’t prove that AC was any more dangerous than DC, and noted that the voltage that entered a customer’s house in the Westinghouse system was less than half the voltage of the Edison system.

In 1886, the New York State legislature had authorized a commission to investigate a more humane alternative to hanging as a method of capital punishment. The commission recommended that hanging be replaced by an entirely new form of capital punishment: death by electricity (the term electrocution had yet to be coined). On June 4, 1888, the state legislature passed a law establishing death by electricity as the preferred method for future executions, and ordered a panel of experts to recommend how to implement the new law.

Brown’s dog experiments came at just the right time for the commission. There was scant scientific information about the effects of electricity on living creatures, and no data at all on what type of current and voltage was sufficient to kill a human being. The panel’s inquiries also came at a fortunate time for Brown and Edison. If the commission could be convinced that AC was so reliably deadly that it would make a splendid means of killing human beings, it would deal a devastating blow to the Westinghouse forces and the AC standard. Few families would want to welcome the executioner’s current into their homes.

Before he was finished, Brown experimented on forty-four dogs at the Edison lab, torturing them all and killing all but a handful. Brown showed no remorse over the suffering he inflicted, nor any scruples about interpreting the results.

More experiments with calves and horses followed….and the battle raged on.

AC won, of course, in the end.

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