DC Power Supply

Posted by PITHOCRATES - February 13th, 2013

Technology 101

Every DC Power Supply has a Transformer, a Rectifier Circuit and a Voltage Regulation Circuit

Alternating current (AC) power is one of the greatest technological developments of mankind.  It gives us the modern world we live in.  We can transmit it over very long distances.  Allowing a few power plants to power large geographic areas.  Something Thomas Edison’s direct current (DC) power just couldn’t do.  Which is a big reason why he lost the War of Currents to George Westinghouse and Nikola Tesla.  AC power also allows the use of transformers.  Allowing us to take the one voltage produced by a power plant and convert it to any voltage we need.

AC power can power our home lighting.  Our air conditioning.  Our electric stove.  Our refrigerator.  Our doorbell.  Pretty much all of the non-fun things in our house.  Things with electric motors in them.  Heating elements.  Or solenoids.  But one thing AC power can’t do is power the fun things in our homes.  Televisions.  Our audio equipment.  Our cable/satellite boxes.  Pretty much anything that doesn’t have an electric motor, heating element or solenoid in it.  These things that process information or audio and video signals.  Or all of the above.  Things that have circuit boards.  With electronic components.  The kind of things that only work with DC power.

Of course all of these things in our homes plug into AC wall receptacles.  Even though they are DC devices.  So what gives?  How can we use AC power to operate DC devices?  With a little something we call a DC power supply.  And every one of those fun things has one.  Either one built-in.  Or an external power pack at the end of a cord.  Every DC power supply has three parts.  There is a transformer to step down the AC voltage.  A rectifier circuit.  And a voltage regulation circuit.

A Diode is a Semiconductor Device that allows a Current to pass through when there is a Forward Bias

The typical electrical receptacle in a house is 120 volt AC.  An AC power cord brings that into our electronic devices.  And the first thing it connects to is a transformer.  Such as a 120:24 volt transformer.  Which steps the 120 volts down to 24 volts AC.  Where the waveform looks like this.

DC Power Supply AC Input

The voltage of AC power rises and falls.  It starts at zero.  Rises to a maximum positive voltage.  Then falls through zero to a maximum negative voltage.  Then rises back to zero.  This represents one cycle.  It does this 60 times a second.  (In North America, at least.  In Europe it’s 50 times a second.)  As most electronic devices are made from semiconductors this is a problem.  For semiconductor devices use low DC voltages to cause current to flow through PN junctions.  A voltage that swings between positive and negative values would only make those semiconductor devices work half of the time.  Sort of like a fluorescent light flickering in the cold.  Only these circuits wouldn’t work that well.  No, to use these semiconductors we need to first get rid of those negative voltages.  By rectifying them to positive voltages.  When we do we get a waveform that looks like this.

DC Power Supply Rectified

A diode is a semiconductor device that allows a current to pass through when there is a forward bias.  And it blocks current from passing through when there is a reverse bias.  An alternating voltage across a diode alternates the bias back and forth between forward bias and reverse bias. Using one diode would produce a waveform like in the first graph above only without the negative parts.  If we use 4 diodes to make a bridge rectifier we can take those negative voltages and make them positive voltages.  Basically flipping the negative portion of the AC waveform to the positive side of the graph.  So it looks like the above waveform.

All Electronic Devices have a Section built Inside of them called a Power Supply

The rectified waveform is all positive.  There are no negative voltages.  But the voltage is more of a series of pulses than a constant voltage.  Varying between 0 and 24 volts.  But our electronic devices need a constant voltage.  So the next step is to smooth this waveform out a little.  And we can do this by adding a capacitor to the output of the bridge rectifier.  Which sort of acts like a reservoir.  It stores charge at higher voltages.   And releases charge at lower voltages.  As it does it smooths out the waveform of our rectified voltage.  Making it less of a series of pulses and more of a fluctuating voltage above and below our desired output voltage.  And looks sort of like this.

DC Power Supply Capacitor

This graph is exaggerated a little to show clearly the sinusoidal waveform.  In reality it may not fluctuate quite so much.  And the lowest voltage would not fall below the rated DC output of the DC power supply.  Please note that now we have a voltage that is always positive.  And never zero.  As well as fluctuating in a sinusoidal waveform at twice the frequency of the original voltage.  The last step in this process is voltage regulation.  Another semiconductor device.  Typically some transistors forming a linear amplifier.  Or an integrated circuit with three terminals.  An input, an output and a ground.  We apply the above waveform between the input and ground.  And these semiconductor devices will change voltage and current through the device to get the following output voltage (for a 12 volt DC power supply).

DC Power Supply DC Output

All electronic devices that plug into a wall outlet with a standard AC power cord have a section built inside of them called a power supply.  (Or there is an external power supply.  Small ones that plug into wall outlets.  Or bigger ones that are located in series with the power cord.)  And this is what happens inside the power supply.  It takes the 120 volt AC and converts it to 12 volts DC (or whatever DC voltage the device needs).  Wires from this power supply go to other circuit boards inside these electronic devices.  Giving the electronic components on these circuit boards the 12 volt DC power they need to operate.  Allowing us to watch television, listen to music or surf the web.

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Electric Power, Alternating Current, Transformers, Magnetic Flux, Turns Ratio, Electric Panel and Circuit Breakers

Posted by PITHOCRATES - February 6th, 2013

Technology 101

AC Power is Superior to DC Power because it can Travel Farther and it Works with Transformers

Thanks to Nikola Tesla and his alternating current electric power we live in the world we have today.  The first electric power was direct current.  The stuff that Thomas Edison gave us.  But it had some serious drawbacks.  You needed a generator for each voltage you used.  The low-voltage of telephone systems would need a generator.  The voltage we used in our homes would need another generator.  And the higher voltages we used in our factories and businesses would need another generator.  Requiring a lot of power cables to hang from power poles along our streets.  Almost enough to block out the sun.

Another drawback is that direct currents travel a long way.  And spend a lot of time moving through wires.  Generating heat.  And dropping some power along the way due to the resistance in the wires.  Greatly minimizing the area a power plant can provide power to.  Requiring many power plants in our cities and suburbs.  Just imagine having three coal-fired power plants around your neighborhood.  The logistics and costs were just prohibitive for a modern electric world.  Which is why Thomas Edison lost the War of Currents to Nikola Tesla.

So why is alternating current (AC) superior to direct current (DC) for electric power?  AC is more like a reciprocating motion in an internal combustion engine or a steam locomotive.  Where short up & down and back & forth motion is converted into rotation motion.  Alternating current travels short distances back and forth in the power cables.  Because they travel shorter distances in the wires they lose less power in power transmission.  In fact, AC power lines can travel great distances.  Allowing power plants tucked away in the middle of nowhere power large geographic areas.  But there is another thing that makes AC power superior to DC power.  Transformers.

The Voltage induced onto the Secondary Windings is the Primary Voltage multiplied by the Turns Ratio

When an alternating current flows through a coiled wire it produces an alternating magnetic flux.  Magnetic flux is a measure of the strength and concentration of the magnetic field created by that current.  When this flux passes through another coiled wire it induces a voltage on that coil.  This is a transformer.  A primary and secondary winding where an alternating current applied on the primary winding induces a voltage on the secondary winding.  Allowing you to step up or step down a voltage.  Allowing one generator to produce one voltage.  While transformers throughout the power distribution network can produce the many voltages needed for doorbells, electrical outlets in our homes and the equipment in our factories and businesses.  And any other voltage for any other need.

We accomplish this remarkable feat by varying the number of turns in the windings.  If the number of turns is equal in the primary and the secondary windings then so is the voltage.  If the number of turns in the primary windings is greater than the number of turns in the secondary windings the transformer steps down the voltage.  If the number of turns in the secondary windings is greater than the number of turns in the primary windings the transformer steps up the voltage.  To determine the voltage induced onto the secondary windings we divide the secondary turns by the primary turns.  Giving us the turns ratio.  Multiplying the turns ratio by the voltage applied to the primary windings gives us the voltage on the secondary windings.  (Approximately.  There are some losses.  But for the sake of discussion assume ideal conditions.)

If the turns ratio is 20:1 it means the number of turns on the primary windings is twenty times the turns on the secondary windings.  Which means the voltage on the primary windings will be twenty times the voltage on the secondary windings.  Making this a step-down transformer.  So if you connected 4800 volts to the primary windings the voltage across the secondary windings will be 240 volts (4800/20).  If you attached a wire to the center of the secondary coil you can get both a 20:1 turns ratio and a 40:1 turns ratio.  If you measure a voltage across the entire secondary windings you will get 240 volts.  If you measure from the center of the secondary and either end of the secondary windings you will get 120 volts.

The Power Lines running to your House are Two Insulated Phase Conductors and a Bare Neutral Conductor

This is a common transformer you’ll see atop a pole in your backyard.  Where it is common to have 4800-volt power lines running at the top of poles running between houses.  On some of these poles you will see a transformer mounted below these 4800-volt lines.  The primary windings of these transformers connect to the 4800-volt lines.  And three wires from the secondary windings connect to wires running across these poles below the transformers.  Two of these wires (phase conductors) connect to either end of the secondary windings.  Providing 240 volts.  The third wire attaches to the center of the secondary windings (the neutral conductor).  We get 120 volts between a phase conductor and the neutral conductor.

The power lines running to your house are three conductors twisted together in a triplex cable.  Two insulated phase conductors.  And a bare neutral conductor.  These enter your house and terminate in an electric panel.  The two phase conductors connect to two bus bars inside the panel.  The neutral conductor connects to a neutral bus inside the panel.  Each bus feeds circuit breaker positions on both sides of the panel.  The circuit breaker positions going down the left side of the panel alternate between the two buss bars.  Ditto for the circuit breaker positions on the right side.

A single-pole circuit breaker attaches to one of the bus bars.  Then a wire from the circuit breaker and a wire from the neutral bus leave the panel and terminate at an electrical load.  Providing 120 volts to things like wall receptacles where you plug things into.  And your lighting.  A 2-pole circuit breaker attaches to both bus bars.  Then two wires from the circuit breaker leave the panel and attach to an electrical load.  Providing 240 volts to things like an electric stove or an air conditioner.  Then a reciprocating (push-pull) alternating current runs through these electric loads.  Driven by the push-pull between the two bus bars.  And between a bus bar and the neutral bus.  Which is driven by the push-pull between the conductors of the triplex cable.  Driven by the push pull of secondary windings in the transformer.  Driven by the push-pull of the primary windings.  Driven by the push-pull in the primary cables connected to the primary windings.  And all the way back to the push-pull of the electric generator.  All made possible thanks to Nikola Tesla.  And his alternating current electric power.

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The Horse, Waterwheel, Steam Engine, Electricity, DC and AC Power, Power Transmission and Electric Motors

Posted by PITHOCRATES - December 26th, 2012

Technology 101

(Original published December 21st, 2011)

A Waterwheel, Shaft, Pulleys and Belts made Power Transmission Complex

The history of man is the story of man controlling and shaping our environment.  Prehistoric man did little to change his environment.  But he started the process.  By making tools for the first time.  Over time we made better tools.  Taking us into the Bronze Age.  Where we did greater things.  The Sumerians and the Egyptians led their civilization in mass farming.  Created some of the first food surpluses in history.  In time came the Iron Age.  Better tools.  And better plows.  Fewer people could do more.  Especially when we attached an iron plow to one horsepower.  Or better yet, when horses were teamed together to produce 2 horsepower.  3 horsepower.  Even 4 horsepower.  The more power man harnessed the more work he was able to do.

This was the key to controlling and shaping our environment.  Converting energy into power.  A horse’s physiology can produce energy.  By feeding, watering and resting a horse we can convert that energy into power.  And with that power we can do greater work than we can do with our own physiology.  Working with horse-power has been the standard for millennia.  Especially for motive power.  Moving things.  Like dragging a plow.  But man has harnessed other energy.  Such as moving water.  Using a waterwheel.  Go into an old working cider mill in the fall and you’ll see how man made power from water by turning a wheel and a series of belts and pulleys.  The waterwheel turned a main shaft that ran the length of the work area.  On the shaft were pulleys.  Around these pulleys were belts that could be engaged to transfer power to a work station.  Where it would turn another pulley attached to a shaft.  Depending on the nature of the work task the rotational motion of the main shaft could be increased or decreased with gears.  We could change it from rotational to reciprocating motion.  We could even change the axis of rotation with another type of gearing.

This was a great step forward in advancing civilization.  But the waterwheel, shaft, pulleys and belts made power transmission complex.  And somewhat limited by the energy available in the moving water.  A great step forward was the steam engine.  A large external combustion engine.  Where an external firebox heated water to steam.  And then that steam pushed a piston in a cylinder.  The energy in expanding steam was far greater than in moving water.  It produced far more power.  And could do far more work.  We could do so much work with the steam engine that it kicked off the Industrial Revolution.

Nikola Tesla created an Electrical Revolution using AC Power

The steam engine also gave us more freedom.  We could now build a factory anywhere we wanted to.  And did.  We could do something else with it, too.  We could put it on tracks.  And use it to pull heavy loads across the country.  The steam locomotive interconnected the factories to the raw materials they consumed.  And to the cities that bought their finished goods.  At a rate no amount of teamed horses could equal.  Yes, the iron horse ended man’s special relationship with the horse.  Even on the farm.  Where steam engines powered our first tractors.  Giving man the ability to do more work than ever.  And grow more food than ever.  Creating greater food surpluses than the Sumerians and Egyptians could ever grow.  No matter how much of their fertile river banks they cultivated.  Or how much land they irrigated.

Steam engines were incredibly powerful.  But they were big.  And very complex.  They were ideal for the farm and the factory.  The steam locomotive and the steamship.  But one thing they were not good at was transmitting power over distances.  A limitation the waterwheel shared.  To transmit power from a steam engine required a complicated series of belts and pulleys.  Or multiple steam engines.  A great advance in technology changed all that.  Something Benjamin Franklin experimented with.  Something Thomas Edison did, too.  Even gave us one of the greatest inventions of all time that used this new technology.  The light bulb.  Powered by, of course, electricity.

Electricity.  That thing we can’t see, touch or smell.  And it moves mysteriously through wires and does work.  Edison did much to advance this technology.  Created electrical generators.  And lit our cities with his electric light bulb.  Electrical power lines crisscrossed our early cities.  And there were a lot of them.  Far more than we see today.  Why?  Because Edison’s power was direct current.  DC.  Which had some serious drawbacks when it came to power transmission.  For one it didn’t travel very far before losing much of its power. So electrical loads couldn’t be far from a generator.  And you needed a generator for each voltage you used.  That adds up to a lot of generators.  Great if you’re in the business of selling electrical generators.  Which Edison was.  But it made DC power costly.  And complex.  Which explained that maze of power lines crisscrossing our cities.  A set of wires for each voltage.  Something you didn’t need with alternating current.  AC.  And a young engineer working for George Westinghouse was about to give Thomas Edison a run for his money.  By creating an electrical revolution using that AC power.  And that’s just what Nikola Tesla did.

Transformers Stepped-up Voltages for Power Transmission and Stepped-down Voltages for Electrical Motors

An alternating current went back and forth through a wire.  It did not have to return to the electrical generator after leaving it.  Unlike a direct current ultimately had to.  Think of a reciprocating engine.  Like on a steam locomotive.  This back and forth motion doesn’t do anything but go back and forth.  Not very useful on a train.  But when we convert it to rotational motion, why, that’s a whole other story.  Because rotational motion on a train is very useful.  Just as AC current in transmission lines turned out to be very useful.

There are two electrical formulas that explain a lot of these developments.  First, electrical power (P) is equal to the voltage (V) multiplied by the current (I).  Expressed mathematically, P = V x I.  Second, current (I) is equal to the voltage (V) divided by the electrical resistance (R).  Mathematically, I = V/R.  That’s the math.  Here it is in words.  The greater the voltage and current the greater the power.  And the more work you can do.  However, we transmit current on copper wires.  And copper is expensive.  So to increase current we need to lower the resistance of that expensive copper wire.  But there’s only one way to do that.  By using very thick and expensive wires.  See where we’re going here?  Increasing current is a costly way to increase power.  Because of all that copper.  It’s just not economical.  So what about increasing voltage instead?  Turns out that’s very economical.  Because you can transmit great power with small currents if you step up the voltage.  And Nikola Tesla’s AC power allowed just that.  By using transformers.  Which, unfortunately for Edison, don’t work with DC power.

This is why Nikola Tesla’s AC power put Thomas Edison’s DC power out of business.  By stepping up voltages a power plant could send power long distances.  And then that high voltage could be stepped down to a variety of voltages and connected to factories (and homes).  Electric power could do one more very important thing.  It could power new electric motors.  And convert this AC power into rotational motion.  These electric motors came in all different sizes and voltages to suit the task at hand.  So instead of a waterwheel or a steam engine driving a main shaft through a factory we simply connected factories to the electric grid.  Then they used step-down transformers within the factory where needed for the various work tasks.  Connecting to electric motors on a variety of machines.  Where a worker could turn them on or off with the flick of a switch.  Without endangering him or herself by engaging or disengaging belts from a main drive shaft.  Instead the worker could spend all of his or her time on the task at hand.  Increasing productivity like never before.

Free Market Capitalism gave us Electric Power, the Electric Motor and the Roaring Twenties

What electric power and the electric motor did was reduce the size and complexity of energy conversion to useable power.  Steam engines were massive, complex and dangerous.  Exploding boilers killed many a worker.  And innocent bystander.  Electric power was simpler and safer to use.  And it was more efficient.  Horses were stronger than man.  But increasing horsepower required a lot of big horses that we also had to feed and care for.  Electric motors are smaller and don’t need to be fed.  Or be cleaned up after, for that matter.

Today a 40 pound electric motor can do the work of one 1,500 pound draft horse.  Electric power and the electric motor allow us to do work no amount of teamed horses can do.  And it’s safer and simpler than using a steam engine.  Which is why the Roaring Twenties roared.  It was in the 1920s that this technology began to power American industry.  Giving us the power to control and shape our environment like never before.  Vaulting America to the number one economic power of the world.  Thanks to free market capitalism.  And a few great minds along the way.

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Silicon, Semiconductor, LED, Photon, Photovoltaic Effect, Photocell, Solar Panel, Converter, Battery and Solar Power Plant

Posted by PITHOCRATES - July 4th, 2012

Technology 101

A Photocell basically works like a Light Emitting Diode (LED) in Reverse

Solar power is based on the same technology that that gave us the electronic world.  Silicon.  That special material in the periodic table that has four electrons in its valence (i.e., outer most) shell.  And four holes that can accept an electron.  Allowing it to form a perfect silicon crystal.  When these silicon atoms come together their four valence electrons form covalent bonds with the holes in neighboring silicon atoms.  These silicon atoms share their valence electrons so that each silicon atom now has a full valence shell of eight electrons (with four of their own electrons and four shared electrons).  Making that perfect crystal structure.  Which is pretty much useless in the world of semiconductors.  Because you need free electrons to conduct electricity.

When we add impurities (called ‘doping’) to silicon is where the magic starts.  If we add a little bit of an element with five electrons in its valence shell we introduce free electrons into the silicon crystal.  Giving it a negative charge.  If we instead add a little bit of an element with 3 electrons in its valence shell we introduce extra holes looking for an electron to fill it.  Giving it a positive charge.  When we bring the positive (P) and the negative (N) materials together they from a P-N junction.  The free electrons cross the junction to fill the nearby holes.  Creating a neutrally charged depletion zone between the P and the N material.  This is a diode.  If we apply a forward biased voltage (positive battery terminal to the P side and the negative battery terminal to the N side) across this junction current will flow.  Like charges repel each other.  The negative charge pushes the free electrons on the N side of the junction towards the junction.  And the positive charge pushes the holes on the P side of the junction towards the junction.  Where they meet.  With free electrons filling available holes causing current to flow.  A reverse bias does the reverse.  Pulls the holes and electrons away from the junction so they can’t combine and cause current to flow.

It takes energy to move an electron out of its ‘hole’.  And when an electron combines with a hole it emits energy.  Typically this energy is not in a visible wavelength so we see nothing.  However, with the proper use of materials we can shift this wave length into the visible spectrum.  So we can see light.  Or photons.  This is the principle behind the light emitting diode.  Or LED.  An electric current through a P-N junction causes electrons to leave their holes and then recombine with holes.  And when they recombine they give off a photon in the visible spectrum of light.  Which is what we see.  A photocell basically works the other way.  Instead of using voltage and current to create photons we use photons from the sun to create voltage and current.

A Solar Array that could Produce 12,000 Watts under Ideal Conditions may only Produce 2,400 Watts in Reality

When we use the sun to bump electrons free from their shells we call this the photovoltaic (PV) effect.  This produces a small direct current (DC) at a low voltage.  A PV cell (or solar cell) then is basically a battery when hit with sunlight.  Electric power is the product of voltage and current.  So a small DC current and a low voltage won’t power much.  So like batteries in a flashlight we have to connect solar cells together to increase the available power.  So we connect solar cells into modules and modules into arrays.  Or what we commonly call solar panels.  Small panels can power small loads.  Like emergency telephones along the highway that are rarely used.  To channel buoys that can charge a battery during the day to power a light at night.  And, of course, the electronics on our spacecraft.  Where PV cells are very useful as there are no utility lines that run into space.

These work well for small loads.  Especially DC loads.  But it gets a little complicated for AC loads.  The kind we have in our homes.  A typical 1,000 square foot home may have a 100 amp electric service at 240 volts.  Let’s assume that at any given time there could be as much as half of that service (50 amps) in use at any one time.  That’s 12,000 watts.  Assuming a solar panel array generates about 10 watts per square foot that means this house would need approximately 1,200 square feet of solar panels (such as a 60 foot by 20 foot array or a 40 foot by 30 foot array).  But it’s not quite that simple.

The sun doesn’t shine all of the time.  The capacity factor (the percentage of actual power produced divided by the total possible it could produce under the ideal conditions) is only about 15-20%.  Meaning that a 1,200 square foot solar array that could produce 12,000 watts under ideal conditions may only produce 2,400 watts (at a 20% capacity factor).  Dividing this by 120 volts gives you 20 amps.  Or approximately the size of a single circuit in your electrical panel.  Which won’t power a lot.  And it sure won’t turn on your air conditioner.  Which means you’re probably not going to be able to disconnect from the electric grid by adding solar panels to your house.  You may reduce the amount of electric power you buy from your utility but it will come at a pretty steep cost.

Solar Power Plants can be Costly to Build and Maintain even if the Fuel is Free 

Everything in your house that uses electricity either plugs into a standard 120V electrical outlet, a special purpose 240V outlet (such as an electric stove) or is hard-wired to a 240V circuit (such as your central air conditioner).  All of these circuits go back to your electrical panel.  Which is wired to a 240V AC electrical service.  A lot of electronic devices actually operate on DC power but even these still plug into an AC outlet.  Inside these devices there is a power supply that converts the AC power into DC power.  So you’ll need to convert all that DC power generated by solar panels into useable AC power with a converter.  Which is costly.  And reduces the efficiency of the solar panels.  Because when you convert energy you always end up with less than you started with.  The electronics in the converters will heat up and dissipate some of that generated electric power as heat.  If you want to use any of this power when the sun isn’t shining you’ll need a battery to store that energy.  Another costly device.  Another place to lose some of that generated electric power.  And something else to fail.

We typically build large scale solar power plants in the middle of nowhere so there is nothing to shade these solar panel arrays.  From sun up to sun down they are in the sunlight.  They even turn and track the sun as it rises overhead, travels across the sky and sets.  To maximize the amount of sunlight hitting these panels.  Of course the larger the installation the larger the maintenance.  And the panels have to be clean.  That means washing these arrays to keep them dirt and bird poop free.  Some of the biggest plants in service today have about 200 MW of installed solar arrays.  One of the largest is in India.  Charanka Solar Park.  When completed it will have 500 MW of PV arrays on approximately 7.7 square miles of land.  With a generous capacity factor of 30% that comes to 150 MW.  Or about 19 MW/square mile.  The coal-fired Robert W. Scherer Electric Generating Plant in Georgia, on the other hand, generates 3,520 MW on approximately 18.75 square miles.  At a capacity factor of about 90% for coal that comes to about 3,168 MW.  Or about 169 MW/square mile.  About 9 times more power generated per square mile of land used.

 So you can see the reason why we use so much coal to generate our electric power.  Because coal is a highly concentrated source of fuel.  The energy it releases creates a lot of reliable electricity.  Day or night.  Summer or winter.  A large coal-fired electric generating facility needs a lot of real estate but the plants themselves don’t.  Unlike a solar plant.  Where the only way to generate more power is to cover more land with PV solar panels.  To generate, convert and store as much electric power as possible.  All with electronic equipment full of semiconductors that don’t operate well in extreme temperatures (which is why our electronics have vents, heat sinks and cooling fans).  So the ideal conditions to produce electricity are not the ideal conditions for the semiconductors making it all work.  Causing performance and maintenance issues.  Which makes these plants very costly.  Even if the fuel is free. 

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Thomas Edison, Patents, Intellectual Property Rights, Nikola Tesla, George Westinghouse, DC, AC and the War of Currents

Posted by PITHOCRATES - March 27th, 2012

History 101

Thomas Edison protected his Intellectual Property Rights with over 1,000 Patents

Thomas Edison was a great inventor.  A great entrepreneur.  But he wasn’t a great scientist or engineer.  He was home-schooled by his mom.  And didn’t go to college.  But he read a lot.  And loved to tinker.  He grew up in Port Huron, Michigan.  At one end of the train line that ran between Port Huron and Detroit.  Where he sold newspapers and other things to commuters during the Civil War.  Then he saved the life of some kid.  Pulled him out of the way of a runaway boxcar.  The kid’s dad ran the train station.  Out of gratitude for saving his son’s life he taught the young Edison Morse Code.  And trained him to be a telegraph operator.  He mastered it so well that Edison invented a better telegraph machine.  The Quadruplex telegraph.  Because he liked to tinker.

What made him a great entrepreneur and not a great scientist or engineer is that his inventions had a commercial purpose.  He didn’t invent to solve life’s great mysteries.  He invented to make money.  By creating things so great that people would want them.  And pay money for them.  He also had an eye on production costs.  So he could build these things the people wanted at affordable prices.  For if they were too expensive the people couldn’t buy them.  And make him rich.  So his inventions used technology to keep production costs down while keeping consumer interest high.  Because of the profit incentive.  But the POSSIBILITY of profits wasn’t enough to push Edison to set up his invention lab.  Where he employed a team of inventors to work full time inventing things.  And figuring out how to mass-produce inventions that made everyone’s life better.  He needed something else.  Something that GUARANTEED Edison could profit from his inventions.  The patent.  That gave the patent holder exclusive rights to profit from their invention.

Inventors and entrepreneurs spend a lot of money inventing things.  They do this because they know that they can file a patent when they invent something that people will buy.  Protecting their intellectual property rights.  So they alone can profit from the fruit of all their labors.  And Edison was one of these inventors.  One of the most prolific inventors of all time.  Filing over 1,000 patents.  Including one on the incandescent light bulb.  Which was going to replace gas lamps and candles.  And provided a need for another new invention.  Electric power distribution.  Something else he spent a lot of time tinkering with.  Producing electrical generators.  And an electric power distribution system.  Which was going to make him an even richer man.  As he held the patents for a lot of the technology involved.  However, he was not to become as rich as he had hoped on his electric power distribution system.  Not for any patent infringements.  But because of a mistreated former employee who had a better idea.

Thomas Edison and George Westinghouse battled each other in the War of Currents

Nikola Tesla was a brilliant electrical engineer.  But not a great entrepreneur.  So he worked for someone who was.  Thomas Edison.  Until Edison broke a promise.  He offered a substantial bonus to Tesla if he could improve Edison’s electric power generating plants.  He did.  And when he asked for his bonus Edison reneged on his promise.  Telling the immigrant Tesla that he didn’t understand American humor.  Angry, Tesla resigned and eventually began working for George Westinghouse.  An Edison competitor.  Who appreciated the genius of Tesla.  And his work.  Especially his work on polyphase electrical systems.  Using an alternating current (AC).  Unlike Edison’s direct current (DC).  Bringing Edison and Tesla back together again.  In war.

Direct current had some limitations.  The chief being that DC didn’t work with transformers.  While AC did.  With transformers you could change the voltage of AC systems.  You could step the voltage up.  And step it back down.  This gave AC a huge advantage over DC.  Because power equals current multiplied by voltage (P=I*E).  To distribute large amounts of power you needed to generate a high current.  Or a high voltage.  Something both DC and AC power can do.  However, there is an advantage to using high voltages instead of high currents.  Because high currents need thicker wires.  And we make wires out of copper or aluminum.  Which are expensive.  And the DC wires have to get thicker the farther away they get from the generator plant.  Meaning that a DC generating plant could only serve a small area.  Requiring numerous DC power plants to meet the power requirements of a single city.  Whereas AC power could travel across states.  Making AC the current of choice for anyone paying the bill to install an electric distribution system.

So the ability to change voltages is very beneficial.  And that’s something DC power just couldn’t do.  What the generator generated is what you got.  Not the case with AC power.  You can step it up to a higher voltage for distribution.  Then you can step it down for use inside your house.  Which meant a big problem for Edison.  For anyone basing their decision on price alone would choose AC.  So he declared war on AC power.  Saying that it was too dangerous to bring inside anyone’s house.  And he proved it by electrocuting animals.  Including an elephant.  And to show just how lethal it was Edison pushed for its use to replace the hangman’s noose.  Saying that anything as deadly as what states used to put prisoners to death was just too deadly to bring into anyone’s house.  But not even the electric chair could save Edison’s DC power.  And he lost the War of Currents.  For Tesla’s AC power was just too superior to Edison’s DC power not to use. 

Nikola Tesla was a Brilliant Engineer who Preferred Unraveling the Mysteries of the Universe over Business

George Westinghouse would get rich on electrical distribution.  Thanks to Nikola Tesla.  And the patents for the inventions he could have created for Thomas Edison.  If he only recognized his genius.  Which he lamented near death as his greatest mistake.  Not appreciating Tesla.  Or his work.  But Edison did well.  As did Westinghouse.  They both died rich.  Unlike Tesla.

Westinghouse could have made Tesla a very rich man.  But his work in high voltage, high frequency, wireless power led him away from Westinghouse.  For he wanted to provide the world with free electric power.  By creating power transmitters.  That could transmit power wirelessly.  Where an electric device would have an antenna to receive this wireless power.  He demonstrated it to some potential investors.  He impressed them.  But lost their funding when they asked one question.  Where does the electric meter go?  Free electric power was a noble idea.  But nothing is truly free.  Even free power.  Because someone had to generate that power.  And if you didn’t charge those using that power how were you going to pay those generating that power?

Edison and Westinghouse were great entrepreneurs.  Whereas Tesla was a brilliant engineer.  He preferred unraveling the mysteries of the universe over business.  Tesla probably suffered from obsessive-compulsive disorder.  Think of the character Sheldon Cooper on The Big Bang Theory television sitcom.  He was a lot like that character.  Brilliant.  Odd.  And interested in little else but his work.  He lived alone.  And died alone.  A bachelor.  Living in a two-room hotel room in the last decade of his life.  Despite his inventions that changed the world.  And the fortunes he made for others.  Sadly, Tesla did not die a rich man.  Like Edison and Westinghouse.  But he did live a long life.  And few men or women changed the world like he did.  A brilliant mind that comes around but once in a millennium.

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The Horse, Waterwheel, Steam Engine, Electricity, DC and AC Power, Power Transmission and Electric Motors

Posted by PITHOCRATES - December 21st, 2011

Technology 101

A Waterwheel, Shaft, Pulleys and Belts made Power Transmission Complex

The history of man is the story of man controlling and shaping our environment.  Prehistoric man did little to change his environment.  But he started the process.  By making tools for the first time.  Over time we made better tools.  Taking us into the Bronze Age.  Where we did greater things.  The Sumerians and the Egyptians led their civilization in mass farming.  Created some of the first food surpluses in history.  In time came the Iron Age.  Better tools.  And better plows.  Fewer people could do more.  Especially when we attached an iron plow to one horsepower.  Or better yet, when horses were teamed together to produce 2 horsepower.  3 horsepower.  Even 4 horsepower.  The more power man harnessed the more work he was able to do.

This was the key to controlling and shaping our environment.  Converting energy into power.  A horse’s physiology can produce energy.  By feeding, watering and resting a horse we can convert that energy into power.  And with that power we can do greater work than we can do with our own physiology.  Working with horse-power has been the standard for millennia.  Especially for motive power.  Moving things.  Like dragging a plow.  But man has harnessed other energy.  Such as moving water.  Using a waterwheel.  Go into an old working cider mill in the fall and you’ll see how man made power from water by turning a wheel and a series of belts and pulleys.  The waterwheel turned a main shaft that ran the length of the work area.  On the shaft were pulleys.  Around these pulleys were belts that could be engaged to transfer power to a work station.  Where it would turn another pulley attached to a shaft.  Depending on the nature of the work task the rotational motion of the main shaft could be increased or decreased with gears.  We could change it from rotational to reciprocating motion.  We could even change the axis of rotation with another type of gearing.

This was a great step forward in advancing civilization.  But the waterwheel, shaft, pulleys and belts made power transmission complex.  And somewhat limited by the energy available in the moving water.  A great step forward was the steam engine.  A large external combustion engine.  Where an external firebox heated water to steam.  And then that steam pushed a piston in a cylinder.  The energy in expanding steam was far greater than in moving water.  It produced far more power.  And could do far more work.  We could do so much work with the steam engine that it kicked off the Industrial Revolution.

Nikola Tesla created an Electrical Revolution using AC Power

The steam engine also gave us more freedom.  We could now build a factory anywhere we wanted to.  And did.  We could do something else with it, too.  We could put it on tracks.  And use it to pull heavy loads across the country.  The steam locomotive interconnected the factories to the raw materials they consumed.  And to the cities that bought their finished goods.  At a rate no amount of teamed horses could equal.  Yes, the iron horse ended man’s special relationship with the horse.  Even on the farm.  Where steam engines powered our first tractors.  Giving man the ability to do more work than ever.  And grow more food than ever.  Creating greater food surpluses than the Sumerians and Egyptians could ever grow.  No matter how much of their fertile river banks they cultivated.  Or how much land they irrigated.

Steam engines were incredibly powerful.  But they were big.  And very complex.  They were ideal for the farm and the factory.  The steam locomotive and the steamship.  But one thing they were not good at was transmitting power over distances.  A limitation the waterwheel shared.  To transmit power from a steam engine required a complicated series of belts and pulleys.  Or multiple steam engines.  A great advance in technology changed all that.  Something Benjamin Franklin experimented with.  Something Thomas Edison did, too.  Even gave us one of the greatest inventions of all time that used this new technology.  The light bulb.  Powered by, of course, electricity.

Electricity.  That thing we can’t see, touch or smell.  And it moves mysteriously through wires and does work.  Edison did much to advance this technology.  Created electrical generators.  And lit our cities with his electric light bulb.  Electrical power lines crisscrossed our early cities.  And there were a lot of them.  Far more than we see today.  Why?  Because Edison’s power was direct current.  DC.  Which had some serious drawbacks when it came to power transmission.  For one it didn’t travel very far before losing much of its power. So electrical loads couldn’t be far from a generator.  And you needed a generator for each voltage you used.  That adds up to a lot of generators.  Great if you’re in the business of selling electrical generators.  Which Edison was.  But it made DC power costly.  And complex.  Which explained that maze of power lines crisscrossing our cities.  A set of wires for each voltage.  Something you didn’t need with alternating current.  AC.  And a young engineer working for George Westinghouse was about to give Thomas Edison a run for his money.  By creating an electrical revolution using that AC power.  And that’s just what Nikola Tesla did.

Transformers Stepped-up Voltages for Power Transmission and Stepped-down Voltages for Electrical Motors

An alternating current went back and forth through a wire.  It did not have to return to the electrical generator after leaving it.  Unlike a direct current ultimately had to.  Think of a reciprocating engine.  Like on a steam locomotive.  This back and forth motion doesn’t do anything but go back and forth.  Not very useful on a train.  But when we convert it to rotational motion, why, that’s a whole other story.  Because rotational motion on a train is very useful.  Just as AC current in transmission lines turned out to be very useful.

There are two electrical formulas that explain a lot of these developments.  First, electrical power (P) is equal to the voltage (V) multiplied by the current (I).  Expressed mathematically, P = V x I.  Second, current (I) is equal to the voltage (V) divided by the electrical resistance (R).  Mathematically, I = V/R.  That’s the math.  Here it is in words.  The greater the voltage and current the greater the power.  And the more work you can do.  However, we transmit current on copper wires.  And copper is expensive.  So to increase current we need to lower the resistance of that expensive copper wire.  But there’s only one way to do that.  By using very thick and expensive wires.  See where we’re going here?  Increasing current is a costly way to increase power.  Because of all that copper.  It’s just not economical.  So what about increasing voltage instead?  Turns out that’s very economical.  Because you can transmit great power with small currents if you step up the voltage.  And Nikola Tesla’s AC power allowed just that.  By using transformers.  Which, unfortunately for Edison, don’t work with DC power.

This is why Nikola Tesla’s AC power put Thomas Edison’s DC power out of business.  By stepping up voltages a power plant could send power long distances.  And then that high voltage could be stepped down to a variety of voltages and connected to factories (and homes).  Electric power could do one more very important thing.  It could power new electric motors.  And convert this AC power into rotational motion.  These electric motors came in all different sizes and voltages to suit the task at hand.  So instead of a waterwheel or a steam engine driving a main shaft through a factory we simply connected factories to the electric grid.  Then they used step-down transformers within the factory where needed for the various work tasks.  Connecting to electric motors on a variety of machines.  Where a worker could turn them on or off with the flick of a switch.  Without endangering him or herself by engaging or disengaging belts from a main drive shaft.  Instead the worker could spend all of his or her time on the task at hand.  Increasing productivity like never before.

Free Market Capitalism gave us Electric Power, the Electric Motor and the Roaring Twenties

What electric power and the electric motor did was reduce the size and complexity of energy conversion to useable power.  Steam engines were massive, complex and dangerous.  Exploding boilers killed many a worker.  And innocent bystander.  Electric power was simpler and safer to use.  And it was more efficient.  Horses were stronger than man.  But increasing horsepower required a lot of big horses that we also had to feed and care for.  Electric motors are smaller and don’t need to be fed.  Or be cleaned up after, for that matter.

Today a 40 pound electric motor can do the work of one 1,500 pound draft horse.  Electric power and the electric motor allow us to do work no amount of teamed horses can do.  And it’s safer and simpler than using a steam engine.  Which is why the Roaring Twenties roared.  It was in the 1920s that this technology began to power American industry.  Giving us the power to control and shape our environment like never before.  Vaulting America to the number one economic power of the world.  Thanks to free market capitalism.  And a few great minds along the way.

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