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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Primary and General Elections

Posted by PITHOCRATES - December 15th, 2011

Politics 101

The Founding Fathers pledged to each other their Lives, their Fortunes and their Sacred Honor

People have protested and died fighting for the right to vote throughout history.  The American Revolutionary War was over taxation without representation.  Meaning that the American colonies wanted representation in British Parliament.  Something the British government did not allow.  Worse, they started taxing the Americans.  Who had no representation in Parliament.  And this did not go over well with the American colonists.  They had had enough.  They wanted a say in their government.

So the Founding Fathers committed treason.  They signed the Declaration of Independence.  And fought 8 years to have that say in their government.  It took awhile.  And a lot of the signers of the Declaration of Independence suffered for their treason.  They lost their property.  Their wealth.  And even their families.  Who suffered all sorts of brutality at the hands of the British.  These traitors.  Who defied their king.  But the cause persevered.  And the Americans won their independence.  As well as their right to self-government.

Back then people cared.  Enough to pledge to each other their lives, their fortunes and their sacred honor.  But today?  People have other priorities in life.  Where reality television is more important in their lives than having that say in their government.  For they have no idea what the Founding Fathers paid to give us this cushy life of plenty.  And just assume the good times will continue to roll.  Especially if they keep voting for whoever promises to give them more free stuff.

Candidates move to the Center after Winning their Party’s Nomination and become someone Completely Different

In the country that struggled for 8 years to get the right to vote.  In the country that inspired people all around the world to follow them in the pursuit of happiness.  In the very bastion of liberty and self-government.  In America.  Guess how many people vote today in a typical presidential election.  Little more than half of eligible voters.  And that’s in the general election.  It’s far worse in the primary election.  Where we see maybe half of that turnout.  Which is rather sad.  Considering that these are the people who actually pay attention to politics.  For this is where a political party chooses their candidate for the general election.  You see, each party has a platform.  A set of political ideas.  Their core philosophy.  And the people choose who they think will best advance their party platform in the primary election.

So during the primary election candidates try to be that candidate.  The one who will best advance the party platform.  Typically the conservative moves as far right as possible to show his or her conservative bona fides.  And the liberal moves as far left as possible to show his or her liberal bona fides.  Here they’re trying to appeal to the party base.  The hardcore.  Those who are as far away from the political center as is possible.  Those who don’t give a whit about compromise or bipartisanship.  They want a purebred candidate that will take the country where they feel it should be.  They don’t want someone who will reach across the aisle and compromise away their most cherished principles.

The population roughly breaks down to 40% conservative, 20% liberal and 40% moderate/independent.  Which is all fine and dandy during the primary election.  But it’s a bit of a problem during the general election.  For that 40% moderate/independent forms the political center.  That area the candidates run away from during the primary election.  So they must scramble back to it after winning their party’s nomination.  And hope that most of those in the center didn’t pay attention during the primary.  To make the lying easier.  To no longer be who they said they were during the primary.  But to be someone completely different.  Someone who can reach across the aisle.  Someone who can compromise away their base’s most cherished principles.  Someone who believes politics should be bipartisan.  Or, better still, nonpartisan.  In other words, the last person their base would want.

When the Choice is between two Moderates, Democrats will always Choose the Democrat Moderate

Liberals have to run to the center.  For their base only amounts to about 20% of the electorate.  But it’s not quite the same for conservatives.  At 40% of the electorate they don’t have to run the center.  They only need another 10% or so of the vote to win.  So running to the center actually hurts them.  Because a lot of that political center is Democrat.  And if the vote comes down to 2 moderates they’re going to vote for the Democrat moderate over the Republican moderate every time.  Because all things being equal, a Democrat will vote for a Democrat.

When the Republicans ran a moderate who campaigned as someone who would reach across the aisle and compromise away his base’s most cherished principles, John McCain didn’t get the moderate vote.  They voted for the Democrat.  Who lied during the general election and ran as a moderate.  Sometimes he even talked like a conservative.  Even though Barack Obama was as liberal as they came.  At least based on his voting record in public office.

When Republican Ronald Reagan won his party nomination he didn’t run to the center.  He remained a conservative.  And he won.  Because a lot of Democrats voted for him.  The Reagan Democrats.  Because there was a real difference between him and Jimmy Carter.  There was a conservative and a liberal.  And the Reagan Democrats decided to vote for the conservative because they liked the conservative message better than the liberal message.  But when the choice is between two moderates who promise to reach across the aisle more than the other there’s no real difference between the candidates.  And no reason to vote for the other guy when he or she is no different than the one from your own party.

Ignoring the Primary Elections ignores the Philosophical Debate and turns the General Election into a Populist Contest

It is a shame the level of voter apathy in the country that stands for self-government.  Almost half of the eligible voters ignore politics 3 years out of 4.  And only vote in the presidential general election.  It’s a shame because we have a 2-party system.  Like it or not.  There are only two core political philosophies to choose from.  For those in the middle don’t have a philosophy.  A party.  A party platform.  A primary election.  Or a political convention.  They only get involved once every 4 years at the general election.  And ultimately end up voting for a Democrat or a Republican.  Even though they refuse to identify themselves with either party.

But ignoring the primary elections ignores the party platforms.  The meat and potatoes of the philosophical debate.  And turns the general election into nothing but a populist contest.  True democracy.  Mob rule.  With the winner often being the one who promises the most to the least politically informed.

Politics has come a long way since the Founding Fathers pledged to each other their lives, their fortunes and their sacred honor.  It’s probably a good thing they’re not here to see what has become of their self-government.  They wouldn’t like what they would see.  Especially the voter apathy.

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