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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , ,

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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Binary Numbers and Computer Speed

Posted by PITHOCRATES - April 2nd, 2014

Technology 101

Computers are Good at Arithmetic thanks to Binary Numbers

Let’s do a fun little experiment.  Get a piece of paper and a pen or a pencil.  And then using long division divide 4,851 by 34.  Time yourself.  See how long it takes to complete this.  If the result is not a whole number take it to at least three places past the decimal point.  Okay?  Ready……..start.

Chances are the older you are the faster you did this.  Because once upon a time you had to do long division in school.  In that ancient era before calculators.  Younger people may have struggled with this.  Because the result is not a whole number.  Few probably could do this in their head.  Most probably had a lot of scribbling on that piece of paper before they could get 3 places past the decimal point.  The answer to three places past the decimal point, by the way, is 142.676.  Did you get it right?  And, if so, how long did it take?

Probably tens of seconds.  Or minutes.  A computer, on the other hand, could crunch that out faster than you could punch the buttons on a calculator.  Because one thing computers are good at is arithmetic.  Thanks to binary numbers.  The language of all computers.  1s and 0s to most of us.  But two different states to a computer.  That make information the computer can understand and process.  Fast.

A Computer can look at Long Streams of 1s and 0s and make Perfect Sense out of Them

The numbers we use in everyday life are from the decimal numeral system.  Or base ten.  For example, the number ‘4851’ contains four digits.  Where each digit can be one of 10 values (0, 1, 2, 3…9).   And then the ‘base’ part comes in.  We say base ten because each digit is a multiple of 10 to the power of n.  Where n=0, 1, 2, 3….  So 4851 is the sum of (4 X 103) + (8 X 102) + (5 X 101) + (1 X 100).  Or (4 X 1000) + (8 X 100) + (5 X 10) + (1 X 1).  Or 4000 + 800 + 50 + 1.  Which adds up to 4851.

But the decimal numeral system isn’t the only numeral system.  You can do this with any base number.  Such as 16.  What we call hexadecimal.  Which uses 16 distinct values (0, 1, 2, 3…9, A, B, C, D, E, and F).  So 4851 is the sum of (1 X 163) + (2 X 162) + (15 X 161) + (3 X 160).  Or (1 X 4096) + (2 X 256) + (15 X 16) + (3 X 1).  Or 4096 + 512 + 240 + 3.  Which adds up to 4851.  Or 12F3 in hexadecimal.  Where F=15.  So ‘4851’ requires four positions in decimal.  And four positions in hexadecimal.  Interesting.  But not very useful.  As 12F3 isn’t a number we can do much with in long division.  Or even on a calculator.

Let’s do this one more time.  And use 2 for the base.  What we call binary.  Which uses 2 distinct values (0 and 1).  So 4851 is the sum of (1 X 212) + (0 X 211) + (0 X 210) + (1 X 29) + (0 X 28) + (1 X 27) + (1 X 26) + (1 X 25) + (1 X 24) + (0 X 23) + (0 X 22) + (1 X 21) + (1 X 20).  Or (1 X 4096) + (0 X 2048) + (0 X 1024) + (1 X 512) + (0 X 256) + (1 X 128) + (1 X 64) + (1 X 32) + (1 X 16) + (0 X 8) + (0 X 4) + (1 X 2) + (1 X 1).  Or 4096 + 0 + 0 + 512 + 0 + 128 + 64 + 32 + 16 + 0 + 0 + 2 + 1.  Which adds up to 4851.  Or 1001011110011 in binary.  Which is gibberish to most humans.  And a little too cumbersome for long division.  Unless you’re a computer.  They love binary numbers.  And can look at long streams of these 1s and 0s and make perfect sense out of them.

A Computer can divide two Numbers in a few One-Billionths of a Second

A computer doesn’t see 1s and 0s.  They see two different states.  A high voltage and a low voltage.  An open switch and a closed switch.  An on and off.  Because of this machines that use binary numbers can be extremely simple.  Computers process bits of information.  Where each bit can be only one of two things (1 or 0, high or low, open or closed, on or off, etc.).  Greatly simplifying the electronic hardware that holds these bits.  If computers processed decimal numbers, however, just imagine the complexity that would require.

If working with decimal numbers a computer would need to work with, say, 10 different voltage levels.  Requiring the ability to produce 10 discrete voltage levels.  And the ability to detect 10 different voltage levels.  Greatly increasing the circuitry for each digit.  Requiring far more power consumption.  And producing far more damaging heat that requires more cooling capacity.  As well as adding more circuitry that can break down.  So keeping computers simple makes them cost less and more reliable.  And if each bit requires less circuitry you can add a lot more bits when using binary numbers than you can when using decimal numbers.  Allowing bigger and more powerful number crunching ability.

Computers load and process data in bytes.  Where a byte has 8 bits.  Which makes hexadecimal so useful.  If you have 2 bytes of data you can break it down into 4 groups of 4 bits.  Or nibbles.  Each nibble is a 4-bit binary number that can be easily converted into a single hexadecimal number.  In our example the binary number 0001 0010 1111 0011 easily converts to 12F3 where the first nibble (0001) converts to hexadecimal 1.  The second nibble (0010) converts to hexadecimal 2.  The third nibble (1111) converts to hexadecimal F.  And the fourth nibble (0011) converts to hexadecimal 3.  Making the man-machine interface a lot simpler.  And making our number crunching easier.

The simplest binary arithmetic operation is addition.  And it happens virtually instantaneously at the bit level.  We call the electronics that make this happen logical gates.  A typical logical gate has two inputs.  Each input can be one of two states (high voltage or low voltage, etc.).  Each possible combination of inputs produces a unique output (high voltage or low voltage, etc.).  If you change one of the inputs the output changes.  Computers have vast arrays of these logical gates that can process many bytes of data at a time.  All you need is a ‘pulsing’ clock to sequentially apply these inputs.  With the outputs providing an input for the next logical operation on the next pulse of the clock.

The faster the clock speed the faster the computer can crunch numbers.  We once measured clock speeds in megahertz (1 megahertz is one million pulses per second).  Now the faster CPUs are in gigahertz (1 gigahertz is 1 billion pulses per second).  Because of this incredible speed a computer can divide two numbers to many places past the decimal point in a few one-billionths of a second.  And be correct.  While it takes us tens of seconds.  Or even minutes.  And our answer could very well be wrong.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

Uninterruptible Power Supply

Posted by PITHOCRATES - February 12th, 2014

Technology 101

The Battery in a Laptop is basically an Uninterruptible Power Supply (UPS)

When working on a personal computer (PC) you’ve probably learned to save your work.  Often.  So if something happens you won’t lose your data.  For there is nothing more frustrating than writing a report off the top of your head without notes only to suffer a power interruption.  And if you didn’t save your work often everything you typed after the last time you did save your work will be lost.  Forever.

Of course if you were working on a laptop you wouldn’t have to worry about losing your work.  Even if you didn’t save it.  Why?  Because of the battery.  Laptops are portable.  We use them often times where there are no power outlets.  Running them, instead, on the internal battery.  Some models even let you change a battery with a low charge to a freshly charged battery without shutting down your laptop.  Which extends the time you can work without being plugged in.

The battery in a laptop is basically an uninterruptible power supply (UPS).  You can work on a laptop while plugged into an AC outlet.  But if someone trips over the cord and pulls it out of the outlet the laptop will switch over to the battery.  And the only way you would know there was a power interruption is if it was yanked off your lap when the person tripped on the cord.  Because thanks to that battery the computer itself never knew there was a power interruption.

The Main Components of an Offline/Standby UPS are a Charger, a Battery and an Inverter

A PC doesn’t come with a built in battery like the laptop.  But we can add one externally.  Which a lot of people have done.  Not only to prevent the loss of data.  But to protect the electronics inside their PC and other sensitive electronic equipment.  Like a monitor.  A cable modem.  A router.  Even a big screen television.  As sensitive electronic equipment can only operate safely in a narrow band of voltages.  And really don’t like things like surges and spikes coming in on the electrical utility line from a lightning strike.  Or under-voltages on hot summer days when everyone in the neighborhood is running their air conditioners.

A UPS can provide a battery backup.  And it can protect your sensitive electronic equipment from surges, spikes and under-voltages.  Which can cause great harm.  Something those surge protected plug-strips can’t protect you from.  They may take a spike or two.  But they are passive devices.  And can do nothing to protect you from an under-voltage (i.e., a brownout).  Only a UPS can.  Of which there are three major types.  Offline/standby.  Line-interactive.  And Online/double-conversion.

An offline/standby UPS is the least expensive and simplest.  The main components inside the UPS are a charger, a battery and an inverter.  It plugs into an AC outlet.  And the devices you want to protect with it plug into the UPS.  If the input voltage (the voltage at the AC outlet) is within a safe range the AC outlet powers your devices.  Also, the UPS controls circuit will monitor the battery voltage.  If it is too low the controls will turn on the charger and it will charge the battery.  When the voltage on the battery is at the level it should be the controls disconnect the charger.  If the UPS controls detect an over-voltage, an under-voltage or a power loss an internal switch disconnects the AC outlet from your devices.  And connects them to the inverter.  A device that converts the DC voltage from the battery into an AC voltage for your equipment.  It will power your devices from a few minutes to up to a half hour (or more) depending on the power requirements of your devices and the battery size.  If the voltage at the AC outlet returns to normal the internal switch will disconnect the devices from the inverter.  And reconnect them to the AC outlet.  If there is a complete power loss you will have time to save your work and safely power down.

The Online/Double-Conversion provides the Best Power Protection for your most Sensitive Electronics

An offline/standby UPS is an efficient unit as it only consumes power when it charges or switches to the battery.  However, switching to the battery every time there is an over-voltage or under-voltage can shorten the battery life.  A problem the line-interactive UPS doesn’t have.  Because it doesn’t switch to the battery every time there is a power fluctuation in the input power.  The line-interactive UPS is basically an offline/standby UPS with an additional component.  An autotransformer.  Which is basically a transformer with a single winding and multiple secondary taps.  If the input power is within the safe range the voltage in equals the voltage out of the autotransformer.  If the input voltage is too high the controls will switch the output to a different secondary tap that will lower the voltage back to the safe range.  If there is an under-voltage the controls will switch the output to a tap that will raise the voltage back to a safe range.  So that these over and under voltages will be corrected by the autotransformer and not the battery.  Which will remain disconnect from the load devices during these autotransformer corrections.  Thus increasing battery life.

The offline/standby UPS is a little more costly but it will have a longer battery life.  And it will also be efficient as it will take minimum power for the controls to switch the taps on the autotransformer.  But if you want the best power protection for your most sensitive electronic equipment you will get that with the more costly and less efficient online/double-conversion UPS.  This UPS is different.  It takes the power from the AC outlet and converts it into DC voltage.  It then takes this DC voltage and produces a pure AC voltage from it.  Free from any voltage irregularities.  Completely isolating your sensitive electronic equipment from the dangers on the electric grid.  For the electrical loads are not normally connected directly to the AC outlet.  They are always connected to the AC output of the inverter.  Which makes this unit the least efficient of the three as it is always consuming power to power the connected loads.

The battery is always connected in the online/double-conversion UPS.  So in a blackout there is no switching required to transfer the loads to the battery. Making for a seamless transition to battery backup.  Of course, sometimes the electrical components inside the UPS malfunction or fail.  In that case the UPS can switch the loads directly to the AC outlet.  Should imperfect power be better than no power.  They will also have an isolation bypass switch.  So you can switch these units directly to the AC source to service the UPS components.  Which may be necessary due to one drawback of the online/double-conversion UPS.  Because the components are always consuming power they generate more heat than the other two types.  Requiring additional cooling to keep these units operating safely.  But they can overheat and breakdown.  Which makes an isolation bypass switch handy to service these while still powering the connected loads.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , ,

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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , ,

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.

www.PITHOCRATES..com

Share

Tags: , , , , , , , , , , , , , ,

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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , ,

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.”

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , ,

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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , ,

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.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , ,

« Previous Entries