The more Electric Cars people drive the greater the Stress on the Electric Grid

Posted by PITHOCRATES - April 16th, 2014

Week in Review

Have you ever noticed your lights dim when your air conditioner starts?  They do because when an electric motor starts there is a momentary short circuit across the windings.  Causing a great inrush of current as they start rotating.  Once they are rotating that inrush of current drops.  During that surge in current the voltage drops.  Because there is no resistance in a short circuit.  So there is no voltage across a short circuit.  And because everything in your house goes back to your electrical panel that momentary voltage drop affects everything in your house.  Including your lights.  The lower voltage reduces the lighting output.  Momentarily.  Once the air conditioning motor begins to rotate the short circuit goes away and the voltage returns to normal.

Air conditioners draw a lot of power.  And during hot summer days when everyone gets home from work they cause the occasional brownout.  As everybody turns on their air conditioners in the evening.  Stressing the electric grid.  Which is why our power bills rise in the summer months.  For this great rise in demand causes a corresponding rise in supply.  Costing the power companies more to meet that demand.  Which they pass on to us (see Electricity Price Surged to All-Time Record for March by Terence P. Jeffrey posted 4/16/2014 on cnsnews).

The average price for a kilowatthour (KWH) of electricity hit a March record of 13.5 cents, according data released yesterday by the Bureau of Labor Statistics. That was up about 5.5 percent from 12.8 cents per KWH in March 2013.

The price of electricity in the United States tends to rise in spring, peak in summer, and decline in fall. Last year, after the price of a KWH averaged 12.8 cents in March, it rose to an all-time high of 13.7 cents in June, July, August and September.

If the prevailing trend holds, the average price of a KWH would hit a new record this summer.

All-electric cars are more popular in California than in Minnesota.  Because there is little cold and snow in California.  And batteries don’t work so well in the cold.  AAA makes a lot of money jumping dead batteries during cold winter months.  So batteries don’t hold their charge as well in the winter.  Which is when an all-electric car requires more charge.  For the days are shorter.  Meaning that at least part of your daily commute will be in the dark and require headlights.  It is colder.  Requiring electric power for heating.  Windows fog and frost up.  Requiring electric power for defogging and defrosting.  It snows.  Requiring electric power to run windshield wipers.  Slippery roads slow traffic to a crawl.  Increasing the time spent with all of these things running during your commute.  So the all-electric car is more of a warm-weather car.  Where people who don’t live in sunny California may park their all-electric car during the worst of the winter months.  And use a gasoline-powered car instead.

As those on the left want everyone to drive all-electric cars they don’t say much about the stress that will add to the electric grid.  If everyone switched to an electric car in the summer it would be like adding a second air conditioner at every house.  Especially after work.  When everyone gets home and plugs in.  Causing an inrush of current for an hour or so as those discharged batters recharge.  A discharged battery is similar to an electric motor.  As it’s the current flow that recharges the battery cells.  There’s a high current at first.  Which falls as the battery charges.  So summer evenings will have a lot of brownouts during the summer months.  As the added electric load will greatly stress the electric grid during the evenings.  A demand that the power companies will have to supply.  At the same time they’re replacing coal-fired power plants with less reliable renewable forms of power generation.  Such as solar farms.  Which will be fast running out of sunshine as these cars plug in.

If people switch from gasoline to electric power in their cars en masse the average price for a kilowatt-hour will soar.  It’s simple economics.  Supply and demand.  The greater the demand the higher the price.  And there is little economies of scale in power production.  Because more power requires more fuel.  And the kicker is that even people who don’t drive will have to pay more on their electric bills when people switch from gasoline to electric cars.  And their gas bills if gas-fired turbines provide that peak power demand.  Raising the price of natural gas.  Making everyone pay more.  Whereas only drivers of gasoline-powered cars are impacted by the high cost of gasoline.

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Short Circuits, Ground Faults and Ground Fault Circuit Interrupter

Posted by PITHOCRATES - April 9th, 2014

Technology 101

AC Power uses Reciprocating Currents to produce Rotating Electromagnetic Fields

There is a police crime lab television show that can solve a crime from a single fiber.  Many crime lab shows, actually.  Where they use high-tech science and music montages to solve many a crime.  Which is great if you DVR’d the shows as you can fast forward through them.  And save some time.  In one of these shows the writers goofed, though.  Because they didn’t understand the science behind the technology.

Someone murdered a construction worker by sabotaging a power cord.  By cutting off the grounding (or third) prong.  The fake crime scene person said this disabled the ground fault circuit interrupter (GFCI) device in the GFCI receptacle.  Leaving the user of the cord unprotected from ground faults.  So when said worker gripped the drill motor’s metallic case while standing in water and squeezed the trigger he got electrocuted.  And when the investigator saw that someone had cut off the grounding prong of the cord he said there was no way for the GFCI to work.  Which is, of course, wrong.  For the grounding prong has little to do with tripping the GFCI mechanism in a receptacle.

If you look at an electrical outlet you will see three holes.  Two vertical slots and one sort of round one.  Inside of these holes are pieces of metal that connect to wiring that runs back to the electric panel in your house.  One of the slots is the ‘hot’ circuit.  The other slot is the ‘neutral’ circuit.  And the third slot is the ‘ground’ circuit.  Now alternating current (AC) goes back and forth in the wiring.  It will come out of the hot and go into the neutral.  Then it will reverse course and come out of the neutral and go into the hot.  Think of a reciprocating engine where pistons go up and down to produce rotary motion.  AC current does the same to produce rotating electromagnetic fields in an electric motor.

The Current in our Electric Panels wants to Run to Ground

If the current can come out of both the hot and the neutral why aren’t both of these slotted holes hots?  Or both neutrals?  Good question.  The secondary winding on the pole-mounted transformer feeding your house has three wires coming from it.  The secondary is a very long wire wrapped many times around a core.  If you measure the voltage at both ends of this coil of wire you will get 240 volts.  They also attach a third wire to this coil of wire.  Right in the center of the coil.  So if you measure the voltage from this ‘center tap’ to one of the other two wires you will be measuring the voltage across half of the windings.  And get half of the voltage.  120 volts.

These are the three wires they bring into your house and terminate to your electric panel.  The center tap and the two wires coming off the ends of the secondary winding.  They attach each of the two ‘end wires’ to a hot bus bar in the panel.  And attach the center tap to the neutral bus.  They also connect the ground bus to the neutral bus.  A 1-pole circuit breaker attaches to one of the two hot bus bars.  Current travels along a wire attached to the breaker, runs through the house wiring, goes through the electrical load and back to the panel to the neutral bus.  So this back and forth current comes from the 120 voltage produced over half of the secondary coil of wire in the transformer.  Where as a 2-pole breaker attaches to both hot bus bars.  Current travels along a wire attached to one pole of the breaker, runs through the house wiring, through the electric load and back to the panel.  But instead of going to the neutral bus bar it goes to the other pole of the 2-pole breaker and to the other hot bus bar.  So this back and forth current comes from the 240 voltage produced across the whole secondary coil in the transformer.

Current wants to run to ground.  It’s why lightning hits trees.  Because trees are grounded.  The current in our electric panels wants to run to ground, too.  Which we only let it do after it does some work for us.  When we plug a cord into an electric outlet we are bringing the hot and neutral closer together.  Like when we plug in our refrigerator.   When the temperature falls a switch closes completing the circuit between hot and neutral through the compressor in the refrigerator.  So the current can run to ground.  Which is actually a back and forth motion through the conductors to create a rotating electromagnetic field in the compressor.  Which runs back and forth between one of the hot bus bars and the neutral bus bar in the panel.

Ground Faults don’t trip Circuit Breakers when finding an Alternate Path to Ground

When we stand on the ground we are grounded.  We are physically in contact with the ground.  We can lie on the ground and not get an electric shock.  Despite all current wanting to run to ground.  So if all current is running to ground why don’t we get a shock when we contact the ground?  Because we are at the same potential as the ground.  And no current flows between objects at the same potential (i.e., voltage).  This is the reason why we have a ground prong on our cords.  And why we install a bonding jumper between the neutral bus and the ground bus in our panels.  So that everything but the hot bus bars is at the same potential.  So no current flows through anything UNLESS that something is also connected to a wire running back to a hot bus in the panel.

Of course, if there is lightning outside we don’t want to be the tallest object out there.  For that lightning will find us to complete its path to ground.  Just as electricity will inside our house.  This is the purpose of the grounding prong on cords.  And why we ground all metallic components of things we plug into an electric outlet.  So if a hot wire comes loose inside of that thing and comes into contact with the metal case it will create a short circuit to ground for that current.  The current will be so great as it flows with no resistance that it will exceed the trip rating of the circuit breaker.  And open the breaker.  De-energizing everything in contact with that loose hot wire.  Eliminating an electric shock hazard.  For example, you could have a fluorescent light with a metal reflector in your basement.  It could have a loose hot wire that energizes the full metallic exterior of that light.  If you were working in the ceiling and had one hand on a cold water pipe when you came into contract with that light you would get a nasty electric shock.  But if it was grounded properly the breaker would trip before anyone could suffer an electric shock.

Ground faults are a different danger.  Because they don’t trip the circuit breaker in the panel.  Why?  Because it’s not a short circuit to ground.  But current taking a different path to ground.  That doesn’t end inside the electric panel.  For example, if you’re using a hair dryer in the bathroom you may come into contact with water and cold water piping.  Things that can conduct electricity to ground.  And if you are in contact with these alternate paths to ground some of that current in the hot wire will not equal the current in the neutral wire.  Because that back and forth current will be going in and out of the hot bus.  And in and out of a combination of the neutral bus and that alternate path to ground through you.  Electrocuting you.  But because of your body’s resistance the current flow through you will not exceed the breaker rating.  Allowing the current to keep flowing through you.  Perhaps even killing you.  This is why we have GFCI receptacles in our bathrooms, kitchens and anywhere else there may be an alternate path to ground.

So how does a GFCI work?  When current flows through a wire it creates an electromagnetic field around the wire.  If you’re looking into the wire as it runs away from you the field will be clockwise when the current is going away from you.  And counter clockwise when coming towards you.  In an AC circuit there are two conductors with current flow.  And at all times the currents are equal and run in opposite directions.  Cancelling those electromagnetic fields.  Unless there is a ground fault.  And if there is one the current in the neutral will decrease by the amount running to ground.  And the electromagnetic field in the neutral conductor will not cancel out the electromagnetic field in the hot conductor.  The GFCI will sense this and open the circuit.  Stopping all current flow.  Even if the ground prong was cut off.

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FT205: “Liberals reconcile conflicting positions with imaginary logic.” —Old Pithy

Posted by PITHOCRATES - January 17th, 2014

Fundamental Truth

We have Complex Numbers because there is no such thing as a Square-Root of a Negative Number

If we graph AC voltage and AC current we would see two sine waves.  Graphs that rise from zero, reach a peak, fall back through zero, reach a nadir and then rise back up to zero.  Which repeats over and over.  And when we have voltage and current we get power.  If we pick a point in time on our AC voltage and current graphs we can multiply the value for the current by the value of the voltage to arrive at a value for power.  If these two sine waves are on top of each other we will get the highest value for power.  If one graph moves ahead or behind the other (so we can see two sine waves instead of one) we will have a value less than the highest power.

Picture two capital ‘S’s lying on their side.  So they look like one period of a sine wave.  And one is on top of the other so we only see one.  If we draw a vertical line through the highest point on these ‘sine waves’ both ‘S’s will have the same highest value.  Let’s call that value ‘3’.  Giving us a power of 9 (3 X 3).  Now let’s move one ‘sine wave’ to the right.  And look at that same vertical line.  With the one ‘sine wave’ moved they won’t have the same value at that point.  One will be less than the other.  Because the maximum value for that ‘sine wave’ occurs to the right of the maximum value of the other.  Let’s say the value for the moved ‘sine wave’ at that point is now 2.  Giving us a power of 6 (2 X 3).

When the power and current are 100% in phase we get our maximum power.  When they move out of phase we get a value of power less than the maximum.  Even though the voltage and current waves are unchanged.  The degree they are out of phase is called the phase angle.  And it’s a problem for power companies.  Because the typical electric meter only measures part of the power a customer uses.  The real or active power.  Not the reactive power.  And it’s a combination of the active and reactive power that gives us apparent power.  What the power companies produce.  In the ideal world (where the voltage and current sine waves are on top of each other perfectly in phase) reactive power is zero and apparent power equals active power.  Mathematically we express this with complex numbers.  Where there is a real part (the active part).  And an imaginary part (the reactive part).  Where i2 = -1.  Something that can’t happen in the realm of real numbers.  As there is no such thing as a square-root of a negative number.  But it is this use of imaginary numbers that let’s engineers build the world around us.

Criminalizing Cigarette Smoking plus Decriminalizing Marijuana Smoking Equals more Democrat Votes

Complicated, yes?  Few of us understand this.  But that’s okay.  We don’t have to.  Engineers are very smart people that can do remarkable things mathematically to model and build our world.  And when they do that world is a better place.  Which is all most of us care about.  So imaginary numbers may be a foreign concept to most.  But they provide a very ordered and sensical world.  Unlike other imaginary things.  Like unicorns.  Fairies.  And imaginary logic.

Liberals are high practitioners of imaginary logic.  On its face it seems like gibberish.  Illogical.  And nonsensical.  But like complex numbers it’s the combination of these nonsensical parts that serve to advance an agenda.  For example, in their ideal world everyone would abort an unplanned and/or unwanted child.  While also saying that same-sex couples should be able to adopt and raise children.  But how can a same-sex couple adopt a child if no unplanned or unwanted child is given up for adoption?  Having both of these positions is like the square-root of a negative number.  It’s just impossible.  Unless you enter the world of imaginary logic.  Where unfettered abortion plus same-sex adoption equals more Democrat votes.

Liberals have banned cigarette smoking wherever they could.  First there were no smoking sections in restaurants.  Then they banned smoking entirely from restaurants.  Once upon a time people could smoke in the workplace.  Then they forced them into smoking lounges.  Then outside of the building.  And finally a minimum distance away from the doorway.  Because smoking will kill you.  The people around you breathing in second-hand smoke.  And the people breathing in the stink you leave behind after smoking (third-hand smoke).  Smoke in the lungs is the number one killer in America. It is so horrible that no one should be able to smoke.  No one should be able to advertise smoking.  Even the cigarette packages shouldn’t be pretty as that may entice kids to start smoking.  But liberals have no problem with people smoking unfiltered marijuana cigarettes.  With marijuana they take the exact opposite position than they do with cigarettes.  Go ahead and smoke.  You aren’t hurting anyone.  Having both of these positions is like the square-root of a negative number.  It’s just impossible.  Unless you enter the world of imaginary logic.  Where criminalizing cigarette smoking plus decriminalizing marijuana smoking equals more Democrat votes.

Hollywood Liberals hate Cigarettes and Guns but love them in their Movies

Hollywood movie producer Harvey Weinstein recently said on the Howard Stern radio show that he hates the National Rifle Association (NRA).  And is going to make a movie to destroy them.  For he thinks guns in America are a horrible thing.  He hates them.  And hates people having them.  But he loves them when they are in his movies.  And has become quite wealthy glorifying horrific gun violence.  If you are unfamiliar with some of the movies he produced you can look them up on IMDB.  Here are just a few that are filled with over the top and very graphic gun violence (as well as sword violence, knife violence, blunt force violence, etc.).  Django Unchained (2012).  Grindhouse (2007).  Kill Bill: Vol. 1 (2003).  Gangs of New York (2002).  Pulp Fiction (1994).  True Romance (1993).  To name a few.  This is how the View content advisory under Violence and Gore begins for Django Unchained: “Note that most of the violence in this film are [sic] over the top and very graphic.”

Harvey Weinstein is a liberal Democrat.  Who believes the only reason why people are using guns to shoot a lot of people is because those guns are for sale.  Cigarette ads and pretty packaging will entice kids to start smoking.  But showing wholesale violence like in his movies would never encourage a kid to pick up a gun?  For that matter, the next time you see one of these movies note how many people smoke in them (or see Alcohol/Drugs/ Smoking under View content advisory on IMDB).  Having Joe Camel on a cigarette package is going to get a kid to start smoking but seeing his or her favorite movie star smoking—and making smoking look so cool—isn’t?   Of course it is.  Far more than any cigarette ad is.  Just as the vicious gun violence in these movies is desensitizing some kids to gun violence.  And is the reason why young kids are having pretend gun fights at school.  Not because they are card-carrying members of the NRA.  But because they saw it in a movie.

Liberals believe cigarettes and guns are horrible things.  And no one should touch them.  But liberal movie producers fill their movies with cigarettes and guns.  Because they are so cool and fun to watch.  Having both of these positions is like the square-root of a negative number.  It’s just impossible.  Unless you enter the world of imaginary logic.  Where criminalizing cigarette smoking and gun ownership plus glorifying cigarette smoking and vicious gun violence (and sex and drugs) in the movies equals more Democrat votes.  Which is what imaginary logic is all about.  Democrat votes.  Which is why liberals can have conflicting positions on the same subject.  Because they don’t really care about the subject.  Or the people they harm.  They just want the power that comes with getting people to vote Democrat.

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Man arrested for Stealing Electricity for his Electric Car

Posted by PITHOCRATES - December 7th, 2013

Week in Review

A bankruptcy judge just ruled Detroit can file bankruptcy.  Dealing a blow to the union workers and pensioners who will see their benefits cut.  A lot.  But in so doing Detroit may be able to do something it hasn’t been able to afford in a long time.  Turning the streetlights back on.

A lot of these streetlights have burnt out lamps.  Some are damaged.  While others have been shut off to cut costs.  Because the electric power to light these is a large cost item.  Even in Britain some cities are turning their streetlights off during parts of the night because they just can’t afford to keep them on all night long.  Which puts a silly incident like this into a new light (see Why Did This Man Get Arrested for Charging His Electric Car? by Tyler Lopez posted 12/5/2013 on Slate).

Early last month, a police officer approached Kaveh Kamooneh outside of Chamblee Middle School in Georgia. While his 11-year-old son played tennis, Kamooneh was charging his Nissan Leaf using an outdoor outlet. When the officer arrived, he opened the unlocked vehicle, took out a piece of mail to read the address, and let a puzzled Kamooneh know that he would be arrested for theft. Kamooneh brushed the entire incident off. Eleven days later, two deputies handcuffed and arrested him at his home. The charge? Theft of electrical power. According to a statement from the school, a “local citizen” had called the police to report the unauthorized power-up session.

The total cost of the 20 minutes of electricity Kamooneh reportedly used is about 5 cents…

Are political attitudes toward environmentally friendly electric vehicles to blame..?

Contrary to popular belief the ‘fuel’ for electric cars is not free.  It takes fuel (typically coal, natural gas, nuclear, etc.) to generate electric power.  Which is why we all have electric meters at our homes.  So we can pay for the cost of generating that electric power.  Therefore, this guy was stealing electric power.  Even if he lived in the city he stole from.  Because current taxes don’t pay for electric power.  People pay an electric bill based on their electric usage.  As shown on an electric meter.

This illustrates a great problem we will have if large numbers of people switch to electric cars.  This will place a huge burden on our electric generating capacity.  Have you ever placed your car battery (in a standard gasoline-powered car) on a charger when you had a dead battery?  If so you may have noticed the voltage meter on the charger barely move.  Because a dead battery places a ‘short-circuit’ across the charger.  Causing a surge of current to flow through the battery.  Recharging the plates.  As the charge builds up the current starts falling.  And the voltage starts rising.  Imagine great numbers of people plugging in their depleted batteries at the same time.  It will do to the electric grid what air conditioners do to it in the summer.  As a bunch of them turn on the lights dim because of that current surge going to the air conditioners.  Leaving less power available to power the lights (and other electric loads).

Air conditioning was such a problem that utilities placed a separate ‘interruptible’ meter at homes.  So that during the summer when the air conditioner load grew too great the utility could shut off some air conditioners.  To reduce the demand on the generating systems.  People lost their air conditioning for periods of time.  But they got a reduced electric rate because of it.

As more people add an electric car to the electric grid it will strain generating capacity.  And raise electric rates.  To get people to use less electric power.  If demand far exceeds supply electric rates will soar.  Perhaps causing a lot of people to look for a free ‘plug-in’ to escape the high cost of electric power.  Transferring that cost to others.  Like cash-strapped cities who can’t afford to leave the street lights on all night.

Few have thought this out well.  Getting more people to use electricity instead of gasoline at the same time we’re trying to replace reliable coal-fired power plants with intermittent wind and solar farms is a recipe for disaster.  In the form of higher electric bills and rolling blackouts.

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Poling, Paddling, Oarlock, Oar, the Galley, Sail, Square-Rig, Lateen-Rig and the Carrack

Posted by PITHOCRATES - August 14th, 2013

Technology 101

(Originally published January 11th, 2012)

The Modern Container Ship is Powered by Diesel Engines making Ocean Crossings Safe, Reliable and Efficient

Trade required a way to move heavy things in large quantities.  Railroads do a pretty good job of this.  Ever get stopped by a mile long train with double-stack containers?  These are the hot-shot freights.  They get the right-of-way.  Other trains pull aside for them.  And they get the best go-power.  They lash up the newest locomotives to these long freights.  Carrying containers full of expensive treasures like plasma televisions, smartphones, computers, clothing, perfume, cameras, etc.  Unloaded from great container ships days earlier.  And hustled out of these great container seaports to cities across the U.S.

These goods came into the country the way goods have for millennium.  On a ship.  Because when it comes to transporting large cargoes there is no more cost efficient way than by ship.  It’s slow.  Unlike a train.  But it can carry a lot.  Which really reduces the cost of shipping per unit shipped.  Keeping sale prices low.  And profits high.

Diesel engines power the modern container ship.  That either turn a propeller directly.  Or by turning an electric generator.  Which in turn powers an electric motor that turns a propeller.  Makes crossing the oceans pretty much a sure thing these days.  And timely.  Day or night.  Wind or no wind.  With the current.  Or against the current.  But travel on water was not always this safe.  Reliable.  Or efficient.

Galleys were Fast and Maneuverable but Decks full of Rowers left Little Room for Cargo

Earliest means of marine propulsion was a man using a pole.  Standing in a boat with his cargo, he would stick the pole through the water and into the riverbed.  And push.  The riverbed wouldn’t move.  So he would.  And the boat he was standing in.  A man kneeling in a canoe could propel the canoe forward with a paddle.  By reaching forward, dipping the paddle into the water and pulling.  By these strokes he would propel himself forward.  And the canoe he was kneeling in.  We transfer the force of both poling and paddling to the vessel via the man-vessel connection.  The feet.  The knees.  Or, if sitting, the butt.  A useful means of propulsion.  But limited by the strength of the man poling/paddling.

The oarlock changed that.  By adding leverage.  Which was a way to amplify a man’s strength.  An oar differs from a paddle because we attach it to the boat.  In an oarlock.  A pivot point.  An oar is similar to a paddle but longer.  It attaches to the oarlock so that a short length of it extends into the boat while a longer length extends outside of the boat.  The rower then rows.  Facing backwards to the boat’s direction.  His short stroke inside the boat transfers into a longer stroke outside of the boat (the leverage).  And the attachment point allows the rower to use both hands, arms and legs.  He pulls with his arms and pushes with his legs.  The force is transferred through the oarlock and pushes the boat forward.  So a single stroke from an oar pulled a boat much harder than a single stroke of a paddle.  And allowed more rowers to be added.  We call these multiple-oared boats galleys.  Such as the Viking longship.  With up to 10 oars on a side.  Or the Phoenician bireme which had two decks of rowers.  Or the Greek trireme which had three decks of rowers.  Or the Carthaginian/Roman quinquereme which had five decks of rowers.

Of course, decks full of rowers left little room for cargo.  Which is why these ships tended to be warships.  Because they could maneuver fast.  Another means of propulsion was available, though.  Wind.  It had drawbacks.  It didn’t have the quick maneuverability as a galley.  And you couldn’t just go where you want.  The prevailing winds had a large say in where you were sailing to.  But without rowers you had a lot more room for cargo.  And that was the name of the game when it came to international trade.

The Carrack opened the Spice Trade to the European Powers and Kicked Off the Age of Discovery

Our first civilizations used sailing ships.  The Sumerians.  And the Egyptians.  The Egyptians used a combination of sail and oars on the Nile.  Where the winds and current were pretty much constant.  They used wind-power to sail upstream.  And oared downstream.  Both the Egyptians and Sumerians used sail to reach India.  The Phoenicians, Greeks and Romans used sail to ply the Mediterranean.  Typically a single square sail on a single mast perpendicular to the keel.  Then later the triangular lateen parallel to the keel.  A square-rig square sail worked well when the wind was behind you.  While the lateen-rig could sail across the wind. And closer into the wind.

The wind blew a square-rig forward.  Whereas the wind pushed and pulled a lateen-rig forward by redirecting the wind.  The lateen sail split the airstream.  The sail redirects the wind towards the stern, pushing the boat forward.  The wind going over the outside of the sail curved around the surface of the sail.  Creating lift.  Like an airplane wing.  Pulling the boat forward.

It was about this time that Europeans were venturing farther out into the oceans.  And they did this by building ships that combined these sails.  The square rigging allowed them to catch the prevailing winds of the oceans.  And lateen rigging allowed them to sail across the wind.  One of the first ships to combine these types of sails was the carrack.  The Portuguese first put the carrack to sea.  The Spanish soon followed.  Christopher Columbus discovered The Bahamas in a carrack.  Vasco da Gama sailed around Africa and on to India in a carrack.  And Ferdinand Magellan first sailed around the world in a carrack (though Magellan and his other four ships didn’t survive the journey).  It was the carrack that opened the spice trade to the European powers.  Beginning the age of discovery.  And European colonialism.

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Rotational Motion, Windmill, Waterwheel, Steam Engine, Compressed Air and Electric Power

Posted by PITHOCRATES - July 24th, 2013

Technology 101

The Combination of Force and Current of Moving Water on a Waterwheel produced Rotational Motion

Through most of history man has used animals for their source of power.  To do the heavy work in our advancing civilizations.  And they worked very well for linear work.  Going long distances in a straight line.  Such as pulling a carriage.  Or a plow.  Things done outdoors.  A long place typically from where people ate and slept.  So animal urine and feces wasn’t a great problem.  But the closer we brought them to our civilized parts of society it became a problem.  For it brought the smell, the flies and the disease closer to our civilized part of life.

Animals were good for linear work.  But as civilization advanced rotational work became more important.  For as machines advanced they needed to spin.  The more advanced machines needed to spin at a fairly high revolutions per minute (rpm).  We have used animals to produce rotational motion.  By having them walk in a small circle.  To slowly turn a mill stone.  Or some other rotational machine.  But it was inefficient.  As animals can’t work continuously.  Especially when walking in a circle.  They have to rest.  Eat.  And they have to urinate and defecate.  Making it unclean.  And unhealthy.

The first great industrial advance was water power.  Using a waterwheel.  Spun by a current of water.  Either a large force of water moving slow and steady.  Like in a river.  Or a small force of water moving fast and furiously.  Like in a small waterfall.  This combination of force and current produced rotational movement.  And useable power.  The waterwheel produced a rotational motion.  This rotational motion drove a main drive shaft through a factory.  Gear trains could speed up the rpm produced by a slow river current.  Or reduce the rpm produced by a fast waterfall current.  To produce a constant rotational speed.  That was strong enough to drive numerous loads attached to the main drive shaft via belts and pulleys.

Compressed Air Systems allowed us to produce Rotational Motion at our Workstations

Water power was a great advancement over animal power.  But it had one major drawback.  You needed a moving current of water.  Which meant we had to build our factories on the banks of rivers.  Or under a waterfall.  One of the reasons why our first industrial cities were on rivers.  The steam engine changed that.  With a steam engine providing our rotational motion we could put a factory pretty much anywhere.  And the power of steam could do a lot more work than a moving current of water.  So factories grew larger.  But they still relied on a rotating main drive shaft.  Then we started doing something else with our steam engines.  We began compressing air with them.

A current of air can fill masts of sails and push ships across oceans.  Air has mass.  So moving air has energy.  We’ve used windmills to turn millstones to crush our wheat.  Where a large force of a slow moving wind current filled a sail.  And pushed.  But these small currents of air required large sails.  If we compressed that volume of air down and pushed it through a very small air hose we could get a force at the end of that hose similar to what we got with a sail catching a large volume of air.  This allowed us to create rotational motion at a workstation.  Without the need of a rotating main drive shaft.  We could connect an air hose to a handheld drill.  And the compressed air in the air hose could direct a jet of high pressure air onto an ‘air-wheel’ inside the handheld drill.  Which spun the ‘air-wheel’ at a very high rpm.  Spinning the drill bit at a very high rpm.

Compressed air was a great advancement over a rotating main drive shaft.  Instead of belts and pulleys connecting to the main shaft you just had to plug in your pneumatic tool to an air line.  The steam engine’s rotational motion would drive an air compressor.  Typically turning a crankshaft with two pistons attached to it.  When a piston moves down the cylinder it draws air into the cylinder.  When the piston moves up it compresses the air in the cylinder.  The compressed air exits the cylinder and enters a large air tank.  From this air tank they run a network of pipes throughout the factory.  From these pipes hang air hoses with fittings that prevent the air from leaking out.  Keeping the whole system charged under pressure.  Then a worker takes his pneumatic tool.  Plugs it into the fitting on a hanging air hose.  As they snapped together you’ll hear a rush of air blow out.  But once they snap together the joined fittings became airtight.  When the worker presses the trigger on the pneumatic tool the compressed air blows out at a very high current.  Spinning an ‘air-wheel’ that provides useful rotational
motion.

Electric Power generated Rotational Motion eliminated the need of Steam Engines and Compressed Air Systems

As good as this was there were some drawbacks.  It takes time to produce steam when you first start up a steam engine.  Once you have built up steam pressure then you can start producing rotational motion so the air compressor can start compressing air.  This takes time, too.  Then you need a lot of piping to push that air through.  A piping system than can leak.  It was a great system.  But there was room for improvement.  And this last improvement we made was so good that we haven’t made another in over 100 years.  A new way to provide rotational motion at a workstation.  Without requiring a steam boiler.  And air compressor.  Or a vast piping system charged with air pressure.  Something that allows us to plug in and go right to work.  Without waiting for steam or air pressure to build.  And that last advancement was, of course, electric power.

When voltage (force) pushes an electrical current through a wire we get useable power.  Generators at a distant power plant produce voltages that push current through wires.  And these wires can run anywhere.  In the air.  Or underground.  They can travel great distances at dangerous high voltages and low currents.  And we can use transformers to change them to a safer low voltage and a higher current in our factories.  And our homes.  Where we can use that force and current to produce useful rotational motion.  Using electric and magnetic fields inside an electrical motor.

Animals were a poor source of rotational power.  The windmill and the waterwheel were better.  The windmill could go anywhere but the rotational motion was only available when the wind blew.  Waterwheels provided continuous rotational motion but they only worked where there was moving water.  Keeping our early factories on the rivers.  The steam engine let us build factories where there was no moving water.  While an air compressor driven by a steam engine made it much easier to transfer power form the power source to the workstation.  While electric power made that transfer easier still.  It also eliminated the need of the steam engine and the pneumatic piping system.  Allowing us to create rotational motion right at the point of work.  With the ease of plugging in.  And pressing a trigger.  Allowing machines to enter our homes to make our lives easier.  Like the vacuum cleaner.  The clothes washer.  And the air conditioner.  None of which your average homeowner could operate if we depended on a main drive shaft in our house.  Or a steam engine driving a pneumatic system.

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Manual Hand Brake, Dynamic Braking and George Westinghouse’s Failsafe Railway Air Brake

Posted by PITHOCRATES - July 17th, 2013

Technology 101

Getting a Long and Heavy Train Moving was no good unless you could Stop It

Trains shrank countries.  Allowing people to travel greater distances faster than ever before.  And move more freight than ever before.  Freight so heavy that no horse could have ever pulled it.  The only limitation was the power of the locomotive.  Well, that.  And one other thing.  The ability to stop a long and heavy train.  For getting one moving was pretty easy.  Tracks were typically level.  And steel wheels on steel rails offered little resistance.  So once a train got moving it didn’t take much to keep it moving.  Especially when there was the slightest of inclines to roll down.

Getting a long and heavy train moving was no good unless you could stop it.  And stopping one was easier said than done.  As trains grew longer it proved impossible for the locomotive to stop it alone.  So each car in the consist (the rolling stock the locomotive pulls behind it) had a manual brake.  Operated by hand.  By brakemen.  Running along the tops of cars while the train was moving.  Turning wheels that applied the brakes on each car.  Not the safest of jobs.  One that couldn’t exist today.  Because of the number of brakemen that died on the job.  Due to the inherent danger of running along the top of a moving train.  Luckily, today, all brakemen have lost their jobs.  As we have safer ways to stop trains.

Of course, we don’t need to just stop trains.  A lot of the time we just need to slow them down a little.  Such as when approaching a curve.  Going through a reduced speed zone (bad track, wooden bridge, going through a city, etc.).  Or going down a slight incline.  In fact slowing down on an incline is crucial.  For if gravity is allowed to accelerate a train down an incline it can lead to a runaway.  That’s when a train gathers speed with no way of stopping it.  It can derail in a curve.  It can run into another train.  Or crash into a terminal building full of people.   All things that have happened.  The most recent disaster being the Montreal, Maine & Atlantic Railway disaster in Lac-Megantic, Quebec.  Where a parked oil train rolled away down an incline, derailed and exploded.  Killing some 38 people.  While many more are still missing and feared dead.

Dynamic Breaking can Slow a Train but to Stop a Train you need to Engage the Air Brakes

Trains basically have two braking systems today.  Air brakes.  And dynamic braking.  Dynamic braking involves changing the traction motors into generators.  The traction motors are underneath the locomotive.  The big diesel engine in the locomotive turns a generator making electric power.  This power creates powerful magnetic fields in the traction motors that rotate the axles.  The heavier the train the more power it takes to rotate these axles.  It takes a little skill to get a long and heavy train rolling.  Too much power and the steel wheels may slip on the steel rails.  Or the motors may require more power than the generator can provide.  As the torque required to move the train may be greater than traction motors can provide.  Thus ‘stalling’ the motor.  As it approaches stall torque it slows the rotation of the motor to zero while increasing the current from the generator to maximum.  As it struggles to rotate an axle it is not strong enough to rotate.  If this continues the maximum flow of current will cause excessive heat buildup in the motor windings.  Causing great damage.

Dynamic breaking reverses this process.  The traction motors become the generator.  Using the forward motion of the train to rotate the axles.  The electric power this produces feeds a resistive load that draws a heavy current form these traction motors.  Typically it’s the section of the locomotive directly behind the cab.  It draws more than the motors can provide.  Bringing them towards stall torque.  Thus slowing their rotation.  And slowing the train.  Converting the kinetic energy of the moving train into heat in the resistive load.  Which has a large cooling fan located above it to keep it from getting so hot that it starts melting.

Dynamic breaking can slow a train.  But it cannot stop it.  For as it slows the axles spin slower producing less electric power.  And as the electric current falls away it cannot ‘stall’ the generator (the traction motors operating as generators during dynamic braking).  Which is where the air brakes come in.  Which they can use in conjunction with dynamic braking on a steep incline.  To bring a train to a complete stop.  Or to a ‘quick’ stop (in a mile or so) in an emergency.  Either when the engineer activates the emergency brake.  Or something happens to break open the train line.  The air brake line that runs the length of the train.

When Parking a Train they Manually set the Hand Brakes BEFORE shutting down the Locomotive

The first air brake system used increasing air pressure to stop the train.  Think of the brake in a car.  When you press the brake pedal you force brake fluid to a cylinder at each wheel.  Forcing brake shoes or pads to come into contact with the rotating wheel.  The first train air brake worked similarly.  When the engineer wanted to stop the train he forced air to cylinders at each wheel.  Which moved linkages that forced brake shoes into contact with the rotating wheel.  It was a great improvement to having men run along the top of a moving train.  But it had one serious drawback.  If some cars separated from the train it would break open the train line.  So the air the engineer forced into it vented to the atmosphere without moving the brake linkages.  Which caused a runaway or two in its day.  George Westinghouse solved that problem.  By creating a failsafe railway air brake system.

The Westinghouse air brake system dates back to 1868.  And we still use his design today.  Which includes an air compressor at the engine.  Which provides air pressure to the train line.  Metal pipes below cars.  And rubber hoses between cars.  Running the full length of the train.  At each car is an air reservoir.  Or air tank.  And a triple valve.  Before a train moves it must charge the system (train line and reservoirs at each car) to, say, 90 pounds per square inch (PSI) of air pressure.  Once charged the train can move.  To apply the air brakes the engineer reduces the pressure by a few PSI in the train line.  The triple valve senses this and allows air to exit the air reservoir and enter the brake cylinder.  Pushing the linkages to bring the brake shoes into contact with the train wheels.  Providing a little resistance.  Slowing the train a little.  Once the pressure in the reservoir equals the pressure in the train line the triple valve stops the air from exiting the reservoir.  To slow the train more the engineer reduces the pressure by a few more PSI.  The triple valve senses this and lets more air out of the reservoir to again equalize the pressure in the reservoir and train line.  When the air leaves the reservoir it goes to the brake cylinder.  Moving the linkage more.  Increasing the pressure of the brake shoes on the wheels.  Further slowing the train.  The engineer continues this process until the train stops.  Or he is ready to increase speed (such as at the bottom of an incline).  To release the brakes the engineer increases the pressure in the train line.  Once the triple valve senses the pressure in the train line is greater than in the reservoir the air in the brake cylinders vents to the atmosphere.  Releasing the brakes.  While the train line brings the pressure in the reservoir back to 90 PSI.

This system is failsafe because the brakes apply with a loss of air pressure in the train line.  And if there is a rapid decline in air pressure the triple valve will sense that, too.  Say a coupler fails, separating two cars.  And the train line.  Causing the air pressure to fall from 90 PSI to zero very quickly.  When this happens the triple valve dumps the air in an emergency air reservoir along with the regular air reservoir into the brake cylinder.  Slamming the brake shoes onto the train wheels.  But as failsafe as the Westinghouse air brake system is it can still fail.  If an engineer applies the brakes and releases them a few times in a short period (something an experienced engineer wouldn’t do) the air pressure will slowly fall in both the train line and the reservoirs.  Because it takes time to recharge the air system (train line and reservoirs).  And if you don’t give it the time you will decrease your braking ability.  As there is less air in the reservoir available to go to the brake cylinder to move the linkages.  To the point the air pressure is so low that there isn’t enough pressure to push the brake shoes into the train wheels.  At this point you lose all braking.  With no ability to stop or slow the train.  Causing a runaway.

So, obviously, air pressure is key to a train’s air brake system.  Even if the train is just parked air will leak out of the train line.  If you’re standing near a locomotive (say at a passenger train station) and hear an air compressor start running it is most likely recharging the train line.  For it needs air pressure in the system to hold the brake shoes on the train wheels.  Which is why when they park a train they manually set the hand brakes (on a number of cars they determined will be sufficient to prevent the train from rolling) BEFORE shutting down the locomotive.  Once the ‘parking brake’ is set then and only then will they shut down the locomotive.  Letting the air bleed out of the air brake system.  Which appears to be what happened in Lac-Megantic, Quebec.  Preliminary reports suggest that the engineer may not have set enough hand brakes to prevent the train from rolling on the incline it was on when he parked the train for the night.  On a main line.  Because another train was on a siding.  And leaving the lead locomotive in a five locomotive lashup unmanned and running to maintain the air pressure.  Later that night there was a fire in that locomotive.  Before fighting that fire the fire department shut it down.  Which shut down the air compressor that was keeping the train line charged.  Later that night as the air pressure bled away the air brakes released and the hand brakes didn’t hold the train on the incline.  Resulting in the runaway (that may have reached a speed of 63 mph).  Derailment at a sharp curve.  And the explosion of some of its tank cars filled with crude oil.  Showing just how dangerous long, heavy trains can be when you can’t stop them.  Or keep them stopped.

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Primary Services, Power Redundancy, Double-Ended Primary Switchgear and Backup Generators

Posted by PITHOCRATES - July 3rd, 2013

Technology 101

The Higher the Currents the Thicker the Conductors and the Greater the Costs of Electrical Distribution

If you live by a hospital you’ve probably noticed something.  They never lose their power.  You could lose your power in a bad storm.  Leaving you sitting in your house on a hot and humid night with no air conditioning.  No lights.  No television.  No nothing.   And across the way you see that hospital lit up like a Christmas tree.  As if no storm just blew through your neighborhood.  Seemingly immune from the power outage afflicting you.  Why?  Because God loves hospitals.

Actually the reason why their lights never seem to go out has more to do with engineers than God.  And a little thing we call power redundancy.  Engineers know things happen.  And when things happen they often cause power outages.  Something we hate as we’ve become so accustomed to our electric-powered world.  But for us it is really more of an annoyance.  For a hospital, though, it’s not an annoyance.  It’s a life safety issue.  Because doctors and nurses need electric power to keep patients alive.  So engineers design ‘backup plans’ into a hospital’s design to handle interruptions in their electric service.  But first a brief word on power distribution.

Nikola Tesla created AC power transmission and put an end to Thomas Edison’s DC power dreams.  The key to AC power is that the alternating current (AC) allows the use of transformers.  Allowing us to step up and step down voltage.  This is very beneficial for the cost in electric power distribution is a factor of the size of the current carrying conductors.  The higher the currents the thicker the conductors and the greater the costs.  Because power is the product of voltage and current, though, we can reduce the size of the conductors by raising the voltage.  Power (P) equals voltage (E) times current (I).  Or P = I * E.  So for a given power you can have different voltages and currents.  And the higher the voltage the lower the current.  The smaller the conductors.  And the less costly the distribution system.

Neighborhoods typically get a Radial Feed so when we Lose our Power our Neighbors Lose their Power

Generators at power plants produce current at a relatively low voltage.  This power goes from the generators to a transformer.  Which steps this voltage up.  Way up.  To the highest voltages in our electric distribution system.  So relatively small conductors can distribute this power over great distances.  And then a series of substations filled with transformers steps the voltage down further and further until it arrives to our homes at 240 volts.  Delivered to us by the last transformer in the system.  Typically a pole-mounted transformer that steps it down from a 2,400 volt or a 4,800 volt set of cables on the other side of the transformer.  These cables go back to a substation.  Where they terminate to switchgear.  Which is terminated to the secondary side of a very large transformer.  Which steps down a higher voltage (say, 13,800 volt) to the lower 2,400 volt or a 4,800 volt.

We call the 240 volt service coming to our homes a secondary service.  Because it comes from the secondary side of those pole-mounted transformers.  And we can use the voltage coming from those transformers in our homes.  Once you get upstream from these last transformers we start getting into what we call primary services.  A much higher voltage that we can’t use in our homes until we step it down with a transformer.  Some large users of electric power have primary services because the size of conductors required at the lower voltages would be cost prohibited.  So they bring in these higher voltages on a less costly set of cables into what we call primary switchgear.  From that primary switchgear we distribute that primary power to unit substations located inside the building.  And these unit substations have built-in transformers to step down the voltage to a level we can use.

There are a few of these higher primary voltage substations in a geographic area.  They typically feed other substations in that geographic area that step it down further to the voltage on the wires on the poles we see in between our backyards.  That feed the transformers that feed our houses.  Which is why when we lose the power in our house all of our neighbors typically lose their power, too.  For if a storm blows down a tree and it takes down the wires at the top of the poles in between our back yards everyone getting their power from those wires will lose their power.  For neighborhoods typically get a ‘radial’ feed.  One set of feeder cables coming from a substation.  If that set of cables goes down, or if there is a fault on it anywhere in the grid it feeds (opening a breaker in the substation), everyone loses their power.  And they don’t get it back until they fix the fault (e.g., replace cables torn down by a fallen tree).

Hospitals typically have Redundant Primary Electrical Services coming from two Different Substations

Now this would be a problem for a hospital.  Which is why hospitals don’t get radial feeds.  They get redundant feeds.  Typically two primary services.  From two different substations.  You can see this if a hospital has an overhead service.  Look at the overhead wires that feed the hospital.  You will notice a gap between two poles.  There will be two poles where the wires end.  With no wires going between these two poles.  Why?  Because these two poles are the end of the line.  One pole has wires going back to one substation.  The other pole has wires going back to another substation.  These two different primary services feed the main primary switchgear that feeds all the electric loads inside the hospital.

This primary switchgear is double-ended.  Looking at it from left to right you will see a primary fusible switch (where a set of cables from one primary service terminates), a main primary circuit breaker, branch primary circuit breakers, a tie breaker, more branch primary circuit breakers, another main primary circuit breaker and another primary fusible switch (where a set of cables from the other primary service terminates).  The key to this switchgear is the two main breakers and the tie breaker.  During normal operation the two main breakers are closed and the tie breaker is open.  So you have one primary service (from one electrical substation) feeding one end (from the fusible switch up to the tie breaker).  And the other primary service (from the other electrical substation) feeding the other end (from the other fusible switch up to the tie breaker).  If one of the primary services is lost (because a storm blows through causing a tree to fall on and break the cables coming from one substation) the electric controls will sense that loss and open the main breaker on the end that lost its primary service and close the tie breaker.  Feeding the entire hospital off the one good remaining primary service.  This sensing and switching happens so fast that the hospital does not experience a power outage.

This is why a hospital doesn’t lose its power while you’re sitting in the dark suffering in heat and humidity.  Because you have a radial feed.  While the hospital has redundancy.  If they lose one primary service they have a backup primary service.  Unlike you.  And in the rare occasion where they lose BOTH primary services (such as the Northeast blackout of 2003) hospitals have further redundancy.  Backup generators.  That can feed all of their life safety loads until the utility company can restore at least one of their primary services.  These generators can run as long as they can get fuel deliveries to their big diesel storage tank.  That replenishes the ‘day tanks’ at the generators.  Allowing them to keep the lights on.  And their patients alive.  Even while you’re sitting in the dark across the street.  Sweating in the heat and humidity.  With no television to watch.  While people in the hospital say, “There was a power outage?  I did not notice that.”

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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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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.

www.PITHOCRATES.com

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