September 14, 2020 • 47 mins
It's time to talk about uninterruptible power supplies, surge protectors, circuit breakers and other systems designed to make sure the electricity we use is safe for us and our devices.
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Episode Transcript
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Speaker 1 (00:04):
Welcome to tech Stuff, a production from I Heart Radio.
Hey there, and welcome to tech Stuff. I'm your host
Jonathan Strickland, Diamond executive producer with I Heart Radio and
I love all things tech, and today's episode is inspired
by a listener suggestion. Nick Sandor asked on Twitter, remember
(00:28):
the handle for the show is tech Stuff. H s
w if I had done an episode on uninterruptible power
supplies a k a. UPS, but not the UPS that
delivers packages, and also asked if I had maybe covered
surge protectors. So today we're going to expand that request
a little bit and talk about those and some circuit
(00:50):
breakers and fuses and power strips in general, and vampire power.
You know, I vant the suck your vaults. Wow. Okay,
that that sounded way less wrong in my head, but
let's dive in. First, let's talk about electricity and circuits
in general, including topics like voltage and current, because I
(01:14):
find that these concepts can be pretty easy for people
to mix up if they're not working with them regularly
or studying physics. So we use voltage to describe the
electric potential between two different points. Uh, if the electric
potential zero, if there's no difference between them. There's no voltage,
there's no there to make an electric current flow between
(01:39):
the two points, So everyone's just kind of cool and
hanging out where there are. And we're gonna use water
as sort of an analogy to talk about electricity quite
a bit in this episode. So in this case, imagine
you've got two clear beakers of water, and these beakers
have a little spigot at their base, right, So though
(02:01):
the water level is above where the spigot is, and
you've got the exact same amount of water in each speaker,
they're on a level table, so they're on the exact
same elevation with each other. There's no tilt or anything,
and you've got a clear tube connecting the end of
one spigot to the other spigot. Well, now that we've
(02:22):
got these two beakers their level, they have the exact
same amount of water in them. If we open those
spigots up, we're not going to expect to see water
flow from one to the other. Right there, pretty much
gonna stay in equilibrium because the water levels are the same.
There's no pressure there to move the water around. Two
(02:43):
points with zero electric potential are pretty much the same
sort of thing as these two beakers. All right, but
let's say we close the spigots on each beaker. Now
water is still trapped in the tube as well, it
can't go anywhere. And then we lift beaker one and
we placed it on top of a small stack of books,
(03:04):
So now it's at a higher elevation compared to beaker
number two. Beaker number two is still on the surface
of the table. Now, if we open up the two spigots,
what happens, Well, water from beaker one will start to
flow to beaker two. We will reach an equilibrium. Again,
but that's not really important for our understanding of voltage.
(03:26):
The point is, at the moment we open the figots,
the water will flow from beaker one to beaker two.
With voltage, a difference in potential will cause a current
of electricity to flow from one point to the other. Now,
because Ben Franklin made a fifty fifty shot and got
it wrong, we describe current as moving from a positive
(03:48):
charge to a negative charge. That positive moves to negative,
and we frequently describe electricity as a flow of electrons.
That's being a little simplistic, but it serves our purposes.
But electrons are negatively charged particles, so the electron flow
(04:08):
goes from negative to positive. Because remember opposite charges attract
and like charges repel one another. So the electrons move
from a point of higher negative charge to a point
of higher positive charge. So while we describe current as
positive charge moving toward negative, the actual electron flow is
(04:29):
negative towards positive. Yes, it is confusing. No, that's not
going to be the end of where things are confusing
in this episode, but stick with me. It's all understandable.
So the greater the difference in that negative and positive charge,
the greater the voltage. And you can think of voltage
(04:52):
as water pressure. If we're talking about that system we
were mentioning before, if we were to pour a lot
more water into beaker one, filling it up all the
way before we open up the spigots, you know, beager
ones at that higher elevation as well, we would actually
also be increasing the water pressure of the system in general,
(05:12):
and so we would see more pressure pushing the water
through to beaker number two. We see the same sort
of thing with electrical systems, and we measure this pressure
or voltage in volts, so you know, that's easy, and
that pressure metaphor also tells us how much work a
(05:32):
circuit can do. You know what kind of load can
you put on that circuit. Higher voltages can do harder work,
and a typical double A alkaline battery can offer up
one point five volts, which is a relatively small amount
In the United States. A wall outlet pushes out one
(05:53):
twenty volts, which is why you can run heavy appliances
using power from the wall, but a single double A
battery just won't cut it. Current is different. Current is
the rate at which electric charge flows past a specific
point within a circuit. This is the rate of flow
(06:14):
of electric charge, as opposed to voltage, which we can
think of as the energy per unit of charge. So
current describes how much electricity is flowing, even though that's
a little misleading, and voltage describes how much omph that
electricity has. We measure current in apps. Current needs voltage
(06:36):
to flow. If you don't have voltage, you don't have pressure,
you don't have current. It would be like our two
beakers that are side by side with that same level
of water. There would be no flow there either. Materials
that allow current to flow more easily are called conductors,
whereas materials that have high resistance to current flowing through
them are insulators. Now, pretty much every thing has some
(07:01):
level of electrical resistance, even the best conductors, at least
in conditions that most of us are familiar with. Now,
if you habitually cool down conductors to near absolute zero,
then you might be used to working with stuff that
has no electrical resistance a k a. Super conductors. But
for practical purposes, it's something we have to deal with
(07:24):
electrical resistance, and I also have to define circuits. So
a circuit is essentially a closed loop pathway that electricity
can follow. If you open any of that path, if
you break the line of that pathway, the electricity can
no longer flow through. And it's kind of like if
you were driving along a track. Let's say it's a
(07:46):
circular track, you know, like NASCAR racing, but part of
that track is actually underwater and you can't go through
that part. Well, you would start your race and then
you would hit this part where the water was and
you would have to pop and you couldn't actually continue.
Electricity is kind of similar. It has to have that
unbroken path in order for it to flow. So if
(08:08):
you break that path, the circuit no longer allows electricity
to flow. This is the whole basis of switches, right.
If you have an open switch, it means that you
have a broken path and the electricity cannot flow through it.
When you close the switch, you have completed that path
and now electricity can flow freely. So electricity will only
(08:30):
flow through a complete circuit. But that also means that
if you come into contact with a conductor, your body
could serve the same as a switch in a circuit.
You could close a circuit when you come into contact
with a conductor, and electricity will always attempt to return
to its source, and it will always follow the path
(08:53):
of least resistance. In a circuit, however, it will take
all available paths. So if you have let's ay you've
got a pathway in your circuit, and you divided into
three different lines, and you have different amounts of resistance
on each line, most of the current is going to
pass through the pathway that has the least resistance. You'll
still get some current going through the other pathways, but
(09:15):
it will be significantly less. So, if you come into
contact with a conductor and your body represents an area
of lower resistance, you're gonna take the brunt of that electricity,
and that's a that's not a good thing. I'll get
back into why that's not a good thing just in
a little bit. But components in a circuit can be
(09:36):
connected either in series, which means you have one right
after the other in a sort of single pathway, or
they can be connected in parallel, which means they be
in side by side individual pathways. When they're connected in series,
the same amount of current will flow through each component,
but the voltage drops from one component to the next.
(09:58):
In parallel, the voltage across each component will remain the same,
but the total current is divided between each pathway. So
it's it's an opposite situation from the series approach. Now,
when it comes to electrical shocks, amperage a gave the
current is really what we need to worry about, not
(10:20):
the voltages. You know, something we can ignore. But you
know you don't want to come into contact with a
high voltage line. Definitely don't do that. You should never
go near high voltage lines. Take it from electric six
danger danger high voltage. But it doesn't take a very
strong current to do serious damage. At around ten to
(10:44):
twenty milla amps, and a mill amp is one of
an amp. You would feel a zap of a shock.
At between twenty million amps, the current is strong enough
to deliver a powerful, painful shock and you lose control
of your muscles. You know, our bodies communicate and operate
(11:06):
on electrochemical signals, so electricity causes that to really go
hey wire. So at this level, if you were to
grab a wire that has between twenty and seventi five
milliamps a current running through it, you wouldn't be able
to let go. Your hand would seize around that wire. Now,
at around seventy five milliamps, your heart ventricles are affected
(11:30):
by this. They start to twitch uncontrollably, and I mean
that's seriously bad stuff. At one two d milliamps, it's
incredibly dangerous and a shock is often fatal at that
amperage above two hundred bill amps. Interestingly, your body's response
would be to clamp down so hard that you might
(11:51):
actually survive that shock because your heart is unable to
fibrillate to have these uncontrollable vibrations because your chest muscle
squeeze so hard it prevents your heart from fit relating. However,
you would also suffer really terrible burns and possibly damage
to your internal organs. So while you could survive that
(12:13):
kind of a shock, it would really hurt you. You
would be more likely to survive at that level, however,
than if you were to encounter a current of between
one two hundred milli apps that would be more likely
to be fatal. And when we talk about electricity, we
often talk about direct current versus alternating current. Direct current
(12:36):
is the easiest for us to understand. It's very easy
to draw and understand how this works. Electricity flows in
one direction only with direct current. It's like a one
way street. Batteries work this way. So a battery has
a negative terminal and a positive terminal, and electricity will
always flow from negative to positive, whereas the current is
(12:58):
going from positives and i aative, but we've covered that
with alternating current. However, it's like you're switching which terminal
is negative and which one is positive, and you're doing
that many times per second. The voltage actually kind of
moves in a sort of wave. It hits the peak
on one side. When terminal one is the most negative
(13:19):
it can be. In terminal two is the most positive,
it can be then it moves the other way as
the two terminals switch. So remember when I said that
the typical US household gets one volts delivered to outlets.
That is an alternating current. So in the US the
current alternates direction sixty times per second, So every sixty
(13:41):
seconds it goes one volts with the current flowing in
one direction and flips to one volts going in the
other direction sixty times a second. Now I say all this, However,
in reality, there is some variation in the amount of
voltage coming to various outlets in a home, and it
can vary to all sorts of stuff, like the gauge
(14:02):
of wire that was used to wire the house, the
temperature that the wires are at, the installation on the wires,
the distance of the house from the transformer on the street.
But you get the general idea. And moreover, electronics manufacturers
design products that can tolerate a small deviation from the standard,
whatever that standard might be in that particular country, and
(14:23):
different countries do have different standards. I'll be working with
the U S standard in this episode because I live
in the US. So the electricity goes over the power
grid and ultimately gets directed into your house or apartment
or whatever, which represents a new circuit, which in turn
is made up of smaller circuits, kind of wheels within wheels,
as it were. One other thing I should mention our
(14:47):
what's what's are a unit of power. And if you
take an electrical circuit and you multiply the voltage across
that circuit by the amps that are passing through the circuit,
you get watts. Watts equals volts times amps. Most of
our stuff actually runs on direct current, not alternating current.
(15:07):
So these devices that we plug into our walls typically
have what is called a rectifier. Uh. And if you
have devices that have a power brick, the power break
is your rectifier. Typically this converts the alternating current to
direct current. Usually have a much lower voltage as well.
You might wonder why we are even using alternating current anyway,
(15:29):
since most of our stuff is running on d C power,
wouldn't it make sense to just supply DC power instead
of having to convert it? Well, it all comes down
to transmitting electricity over great distances. More than a century ago,
there was a big debate about which approach was the
one to use. Thomas Edison wanted to go with direct current,
(15:51):
which would have required building out lots of power plants
to be close to the load. That is, you would
have to add power plants close to the places that
were actually using the electricity coming from those power plants.
Because it was really hard to send direct current of
sufficient voltage longer distances. You would have to have incredibly
thick cables and you would lose a lot of energy
(16:12):
in the form of heat waste. If you were really
pushing the voltage super hard, then the cables would heat
up to the point where they would just break under
the stress. So alternating current, which was championed by George Westinghouse,
could make use of electrical transformers, and with transformers you
can step up the voltage for long distance transmission, which
(16:35):
is much more efficient, and then you would have other
transformers at the other end to step down the voltage
once it got to wherever you were sending it. A
C power was more practical at the time and one out,
but it did mean having to use rectifiers to change
the A C T D C in order to make
practical use of it. With most appliances. If you're familiar
(16:56):
with the basics of circuits, you know about resistors, These
are elements that have a specific electrical resistance, you know,
a resistance to the flow of current, and they're used
to do all sorts of stuff. For example, the filament
in a light bulb is essentially a resistor which resists
the flow of current, and as current pushes its way
(17:17):
through anyway due to having a sufficient amount of voltage,
some of the electrical energy converts into heat, which heats
up the filament and ultimately causes it to glow. Well. Essentially,
all things you plug into a power outlet are acting
as a type of resistor in the circuit that is
your home's wiring. The appliance represents a constant resistance. Your
(17:41):
home is supplied with a constant voltage, so that means
the current is kept constant as well. Because all of
these things relate to one another. Now that's a good thing,
as good old Tom Harris wrote in a house stuff
works dot com article about circuit breakers. Quote, too much
charge flowing through a circuit at a particular time would
heat the appliances, wires, and the building's wiring two unsafe levels,
(18:05):
possibly causing a fire. End quote. So let's go ahead
and define a power strip. Now that we've got these
basics out of the way. A power strip is a
bunch of outlets that are mounted into a frame of
some sort. Now, while it might appear that these outlets
are in a series, like if you have a long,
thin powder strip, it looks like you've got a series
(18:27):
of outlets, they're actually wired in parallel. If you were
to take one of these apart and don't do that,
but if you were, you would see they're wired and parallel,
not in series. And if you remember, that means the
voltage is going to remain the same for every component
that gets plugged into that strip. That's important because otherwise
you would have a voltage drop if they were in series.
(18:50):
As you plugged more components into the strip, the voltage
would drop further down the series. And if you've got
a few components that require a hefty amount of voltage,
you could find yourself out of luck. The devices wouldn't
receive enough pressure to work. Now, while the voltage will
remain constant across the components plugged into a power strip,
and the resistance remains constant per component, adding more components
(19:14):
means increasing the load of current moving through the power strip.
So as you plug more stuff into a power strip,
the power strip has to supply more amperage. If the
power requirements of the components are super hefty, it could
mean overloading that specific circuit, which could lead to some
of those really bad outcomes like an electrical fire. And
(19:35):
that's where circuit breakers come in. I'll explain them more
in just a second, but first let's take a quick break. Okay,
so without circuit breakers or fuses, there would be no
fail safe to prevent someone from overloading a home electrical
(19:59):
circuit and causing wires to heat up enough to melt
or cause a fire. So thankfully we do have these
elements to help keep us safe as we use electricity.
Let's start with fuses, because they are pretty simple to understand.
A fuse has a thin wire inside that's kind of
like a filament to a light bulb. Fuses are designed
(20:20):
to handle a certain amount of current within a circuit.
If the fuse receives more than that allotted amount of
current based on the type of fuse you're using, then
the electrical energy that's running through that thin wire will
cause it to heat up rapidly and it begins to disintegrate.
It burns through that cuts off the electrical circuit. We
(20:42):
have now cut off that pathway broken it. But the
bummer of the sort of approach is that when that
does happen, you have to replace the fuse. They are
a one use item. Uh so they do protect your
home in the case of a increase in current, which
could be a real problem, but it means also that
(21:03):
once that does happen, you have to go out and
replace the fuse and the fuse box. I used to
live in a house that still had a fuse box
and occasionally we'd have a fuse go out and that
was a real hassle. I mean, just finding the right
fuse to go in the right section was was something
of a challenge at times. Circuit breakers are way easier
from an end user standpoint, and it typically involves opening
(21:26):
up a panel and flicking a switch that has been
turned off to on. So when you flip the switch
to on, it completes a circuit. It allows electricity to
flow through, but if the current running through that circuit
exceeds a certain amount, it trips the switch, so it
turns off. And there's actually a couple of different ways
this can be done, but one of them is using
(21:49):
an electro magnet. The current causes the electro magnet to
generate a magnetic field, and if the current peaks, if
it gets too strong, that magnetic field comes strong enough
to pull a metal lever and mechanically move it to
a different position, which actually causes the switch to flip off.
(22:10):
It's the power of magnetism that pulls the switch into
the off position. It's incredibly clever because that only happens
if the electrical current is strong enough to create that
magnetic field in the electro magnet. So very ingenious design.
Now that's a very high level look at circuit breakers.
It's also not the only way that circuit breakers can work.
(22:33):
But I want to segue over to surge protectors because
that was the actual area of interest that I was
asked about. So circuit breakers are all about cutting off
a circuit once the current becomes too strong. Surge protectors
are about protecting against a quick increase in voltage. So
this is about finding a way to deal with a
(22:54):
sudden increase in electrical pressure. If you like surges, don't
have to laugh very long before they are a problem.
If you get a super fast jump and voltage that
only lasts for a nanosecond or two, we call that
a spike, But if it lasts three nanoseconds or more,
(23:14):
it's a surge. But a nanosecond is one billionth of
a second. So yeah, surges can be quick, far faster
than we can perceive, though we definitely can perceive the
consequences of a surge. Now, if you have something plugged
into an outlet and the outlet experiences a surge, it's
(23:34):
kind of like if you were to have a water
hose connected to a spigot and suddenly that spigott forces
way more water through the hose than it can handle.
The hose itself can burst if there's too much water
pressure inside of it. So voltage surges can cause wires
to melt or make devices work way harder than they
(23:54):
are supposed to. You know, devices are meant to work
at a certain voltage. There you can in add more voltage.
You could create more voltage and thus make the device
work harder than it was intended, but that's not a
great idea. So, for example, the device you've got plugged
into a wall has a motor in it, then the
motor may suddenly operate at a speed much higher than
(24:17):
it was meant to and this might not result in
immediate failure, but it definitely adds to the wear and
tear on a device. It can also be a safety issue,
so you want to avoid surges. A surge protector deals
with a rapid increase in voltage by directing excess current
into the wall outlets. Grounding wire and a grounding wire
(24:40):
is kind of what it sounds like. It's a safety
wire in the outlet that ultimately connects to earth. So
under normal circumstances, this wire does not carry any electricity.
It's it doesn't hold a current. Under normal operating conditions,
it has very low resistance, but current does not flow
(25:01):
through it. The grounding wire is there to serve as
an alternate pathway for current to flow in the event
that something has gone wrong. By the way, there's also
a grounded neutral conductor sometimes called a ground wire or
grounded wire. So you have a grounding wire and a
grounded wire, and yeah, that makes stuff gets super confusing
(25:24):
because it's very easy to mix up grounding wire and
grounded wire. So let's step back for a second, and honestly,
we can get around this confusion if we just call
it the neutral wire in the first place. So at
bare minimum, if you want a circuit, you need two wires.
And let's just imagine a very simple circuit with a
(25:45):
battery and a light bulb and a pair of wires.
So you've got a wire that connects the negative terminal
of the battery where the electrons are coming out to
the bulb, and this is the hot wire. It is
carrying electrons to the circuit load. The load being the
component that requires electricity to work, and this example it's
(26:05):
the bulb. The wire that connects the bulb to the
batteries positive terminal is called the neutral wire. This is
how the electrons returned to the battery and complete the circuit.
So if you don't have that neutral wire connecting back
to the battery, you don't have a circuit. No electricity
is flowing, the lamp is going to stay off. It's
only when you complete the circuit by adding this neutral
(26:28):
wire that you are going to have any light on
that that bulb. So with an outlet, the hot wire
carries electricity to the load and the neutral wire carries
the quote unquote used electricity back. So the neutral or
grounded wire is actually carrying an electric current under normal
operating conditions, unlike the grounding wire, which is a safety precaution. Now,
(26:52):
this actually gets more complicated because in the US you
actually have two hot wires coming in circuits and one
neutral wire coming in, and then you have the grounding
wires all part of the outlets that you're using. But
really that merits its own podcasts, so I'm not gonna
go into it too much. It's all has to do
(27:12):
with the fact that we're relying on alternating current, but
it doesn't really matter for the rest of this episode.
So the important thing to remember is that the grounding
wire terminates ultimately in the ground itself, in the earth,
and it allows the circuit to discharge excess electricity in
special circumstances. So, for example, if the hot wire in
(27:33):
a circuit, the one that's carrying electricity to a load,
were to make contact with something other than the intended load,
like say the casing around a light socket, the ground
wire would represent a low resistance pathway for electricity to
flow back out rather than for things to start heating
up and becoming a real problem, because otherwise the casing
(27:56):
is going to act like a resistor. So in a
surge protector, you've got an element that connects the hot
wire to the grounding wire. But you have to be
careful about this, right. You don't want to have just
a simple connection from hot wire to groundwire because then
the electricity is just gonna flow straight to the ground wire.
It's not gonna do any work. So one example of
(28:18):
this is a thing called a metal oxide verista. This
is made up of a piece of metal oxide that
sandwiched between two semiconductors, and the semiconductors have special properties
that determine how they perform within a circuit. Semiconductors typically
can act as either a conductor or an insulator depending
on specific circumstances. In the case of this metal oxide verista,
(28:43):
we would look at the voltage. So at low voltage,
the semiconductors have a very high electrical resistance, and because
electricity wants to follow the path of least resistance, that
electricity is just gonna keep on going past the verista.
It's gonna be like not interested. But at higher the
normal voltage, the semiconductor's resistance drops dramatically. Now electricity can
(29:07):
flow through that pathway easily because there's very low resistance,
so it means current is going to pass through the
hot wire, through the verista and to the grounding wire,
which ultimately terminates in the ground itself, and that discharges
the extract current and returns the voltage in the hot
wire to normal, And so the semiconductors, once the voltage
is normal, will return to their normal resistance and electricity
(29:31):
will follow the usual pathway. What this means for your
electronics is that if there's a surge in voltage, the
extra pressure gets relieved through this grounding wire and doesn't
make it to the devices that you're plugged into the
surge protector itself. It's kind of like a pressure relief
valve in a water pressure system. Now, the metal oxide
(29:53):
verista is just one type of surge protector. There are
lots of others, such as gas discharge arrest rs. I
love the names for these. These have a gas tube
that are that's filled within the inert gas and this
gas can conduct electricity, but its conductivity is variable, so
at low voltages it's not a very good conductor. It's
(30:15):
akin to having a high resistance. At higher voltages, however,
the gas inside the tube begins to ionize, it begins
to release some electrons, so you have some free flowing
electrons in the gas that allows current to flow through
the gas more readily, and so again it acts kind
of like a pressure release. Both the Varista and the
(30:37):
arrestor are based off parallel circuit designs, but you can
also have surge protectors that use series circuit designs. And
if you remember, components that are connected through series have
a lower voltage as you add more loads more components.
These protectors don't bypass surges the way the parallel ones do.
(30:59):
They suppress surges. Oh and and for the parallel based designs,
there's another important thing to keep in mind. These protectors
work by sending that excess electricity to the homes ground wire.
So home needs a grounding wire, like there needs to
be a wire that actually extends down into the ground.
Without that grounding wire, a surge protector wouldn't be any
(31:20):
help because there would be no pathway to serve as
that pressure release system. The US outlets that have three slots.
When you see a three slot outlet in the wall,
those are supposed to be grounded outlets. The D shaped
rounded slot, the the hole in the bottom or sometimes
the top, depending on how the outlet has been installed.
(31:41):
That's the one that connects to the home or buildings
ground wire, or at least it's it's supposed to. Now
let's talk about them buyers, or rather vampire power. So
a lot of our devices don't really turn off when
we turn them off, at least they don't shut down completely. So,
(32:02):
for example, I have a computer mouse that is connected
to a second computer at my desk, and that second
computer is currently turned off, Yet my computer mouse has
led lights that are still lit. Now there's no battery
inside my computer mouse. Clearly my computer mouse must still
be drawing power from the computer, but the computers off,
(32:23):
So what gives Well, my computer, like a lot of electronics,
is actually still drawing some power even when it is
turned off. Televisions tend to be the same way, printers
to Really, a lot of stuff has a type of
standby power mode, so that even when you shut them off,
they're only what you know, Miracle Max would call mostly off,
(32:47):
there's still slightly on. And there are a few reasons
for this, but the big one is that it's very convenient.
It means the devices have a shorter startup time when
we power them on. So when you grab they're clicker
and turn on the old picture box, you don't want
to wait for them hamsters inside to get up to
run speed. I'm sorry I allowed an old prospector to
(33:10):
write that last bit. What I meant to say is
we don't really like a delay between when we turn
something on and when it's actually usable. So standby power
is a kind of cheap mode to cut down on
the weight times we have. So if you power something
on and you're waiting for it to warm up, that's
really frustrating. Standby power helps cut down in that weight time.
(33:32):
Smart power strips are meant to detect when the device
is off but attempting to draw a standby power, and
these power strips cut off the source of that standby power,
thus ensuring that the device is well and truly off.
It's not sipping electricity, and that means using less juice
during the month, which also means a lower power bill.
(33:53):
Is it significant Well? Estimates vary, but analysts say that
stand by power consumption can make up but wween five
and ten percent of a household's energy consumption, so it's
definitely enough to be noticeable. It might be around a
hundred bucks a year in savings, so it's it's you know,
it's not nothing. Smart power strips have some extra circuitry
(34:15):
in them compared to your run of the mill normal
power strip. They still represent a group of outlets that
are mounted in parallel because you still want to make
sure you're not causing a voltage drop from one device
to the next as you plug them in. But they
also contain circuits that monitor a drop in power consumption,
which would indicate a transition into standby power mode, and
(34:35):
at that point, the power strip would break the circuit
to the device, cutting off power. There are different ways
to do this. One common one is to have a
master outlet that then determines whether or not power gets
supplied to some control outlets. This is easier to understand
if I actually use an example. So let's say I've
got a home entertainment system and that consists of my television.
(34:59):
I've got a surround sound system, I've got a video
game console, I've got a Blu ray Player, and I've
got a cable box. Now, let's say I always want
to have the cable box running. Let's say it's also
my DVR and stuff, so I plug that into an
outlet on my smart power strip that is always hot,
meaning it's always going to have power supplied to it
(35:21):
no matter what that outlet is, just like if I
had plugged it straight into the wall. But the surround
sound system, the video game console, and the Blu ray
player are really only useful to me if the television
is also on, So I plugged those three devices into
the control outlets in my smart power strip. The control
(35:43):
outlets take a queue from the master outlet that's where
I plug in my TV, So TV goes into the
master outlet, Blu ray players, surround sound system, video game
consoles into the control outlets. The circuits in the smart
power strip will detect when the TV is on because
they detect an increase in power consumption, So when that happens,
(36:03):
the power strip also allows power to flow to the
devices that are plugged into the control outlets. But if
I turn off my television, the drop in power consumption
tells the power strip that it no longer needs to
supply electricity to those control outlets. So in that case,
the Blu ray player, of the surround sound system, the
video game console, all go dark, they can't sip any
(36:25):
phantom power. That makes sense, right, I mean I can't
use those devices unless the television is on. Anyway, when
we come back, will transition over to uninterruptible power supplies.
But first let's take another quick break. Sometimes the stuff
(36:49):
we count on just asn't dependable. Like electricity, there are
times when the power goes out. Maybe a transformer is
over did which can be pretty darned spectacular, not to
mention loud and dangerous. Maybe something has broken a power
line leading to your home. Whatever the root cause, the
(37:11):
effect is the power goes out in your house, and
that can potentially damage certain electronic devices if they happen
to be plugged in and active at that moment, like computers,
And that's where an uninterruptible power supply or UPS comes in.
These are systems that are intended to supply electronic loads
with sufficient power to continue operations at least for a
(37:33):
short while in the event of a power outage. For
the type that the average person like you or me
might be dealing with. It may just be something that
lasts long enough for us to you know, save whatever
we were doing on the computer and then shutting it
down in a controlled power off cycle. It's not something
that can supply power forever, but rather work as a
(37:56):
type of stop gap while you wait for your electricity
service to come back on. There are a couple of
versions of these uh. In fact, there's really three main types,
but I'm really only going to cover two of them.
A standby UPS is sort of UPS is just waiting
in the wings, so in the event of a power outage,
(38:18):
then it kicks on, using a rechargeable battery as the
power source. These types of UPS systems typically have some
sort of switch to handle the change from supplying power
from the outlet to the devices to switching over to
supplying power from the onboard UPS battery. With continuous UPS devices,
(38:39):
the stuff you plug into the UPS is always drawing
power from the battery, but in turn, the battery is
in a constant state of recharging, drawing power from the
wall outlet. So if the power from the outlet goes out,
the computer or you know, whatever you have plugged into
the up US just keeps drawing power as it always
(39:03):
had because it's always taking power from the battery. It's
only when the UPS battery itself runs out of charge
that you have a problem. But again, the typical operating
procedure here is to use the time that you have
to take care of saving stuff and shutting down your
electronics safely. Um. Granted, it's a different story if you're
talking about industrial uses. In either case, the UPS has
(39:26):
to do something really interesting and it also can seem
a little backward. Okay, remember when I said most of
our devices run on direct current d C, so they
have to have what's called a rectifier to convert the
incoming alternating current from the wall sockets into d C
power that the device can use. Well, batteries if you
(39:50):
recall supply direct current d C power, not alternating current. However,
our devices still need to accept alternating rant even though
they ultimately run on direct current. So this means the
direct current from the battery in the UPS has to
convert into alternating current so it can be sent onto
(40:13):
the devices, which then use rectifiers to convert the alternating
current back into direct current. What a way to run
a railroad. So a rectifier takes a C turns it
into d C. We call devices that do the opposite,
that take DC and turn it into a C. Inverters.
So the UPS has an inverter to take the d
(40:35):
C power out of the battery converted to a C
which goes to the devices rectifier to get converted back
into d C. And to make this even more complicated,
rechargeable batteries need a direct current to recharge, so that
means the UPS actually has its own rectifier. So the
UPS has a rectifier. It takes a C coming from
(40:56):
the wall right, the a C goes to the directive
fire gets converted into d C. That DC power charges
the battery on the UPS. Then from the battery there's
the inverter to convert the d C into a C.
And at this point I really wish Thomas Edison could
have cracked the problem of long range power transmission using
(41:18):
direct current because it really would have simplified things a
ton on the user end. Now, I like to think
of rectifiers and inverters as something Luke Skywalker would really
be interested in. After all, he was really looking forward
to going to Tusky Station and picking up some power converters.
And if you don't get that reference, you need to
watch Star Wars a New Hope. If you're shopping for
(41:41):
UPS systems, chances are you're going to be looking at
stand by UPS devices. They tend to be much less
expensive than continuous UPS devices, and they work pretty well
for most of us. If you oversee something that's really
mission critical, like a server room or something that's a
different story. In those cases, the need for a stable
source of power is enough to justify the higher cost.
(42:02):
Your typical UPS will have some sort of way to
signal that the power has switched over to the battery.
Usually it's a beeping noise, and that gives you the
opportunity to get stuff you know powered down in a
controlled way, and they may also require you to reset
a UPS once power has been restored to the home
or building. I have often worked in offices where you
(42:25):
could hear a beeping going off and realize that someone's
UPS had tripped, and you need to find which one
it was and reset it, and it's a fun game
of hide and seek or lose your sanity. Now, normally
I would have jumped right into history at the beginning
of an episode, but I figured it would make more
(42:46):
sense to kind of tack it on at the end
of this one, to be kind of a little bit
of just bonus tidbit information sort of a pub trivia
kind of bit of info. So, way back in nineteen
thirty two, a guy named John J. Hanley filed for
a patent titled Apparatus for Maintaining an unfailing and uninterrupted
(43:09):
Supply of Electrical Energy. Now, I cannot say for certain
he was the first person to come up with this idea.
In fact, I think it's safe to say that the
idea was one that was forming in a lot of
places around the same time. Because we were becoming more
dependent upon electricity, people saw the need for there to
be some way to have a dependable source of electricity
(43:32):
in case our primary source, the power grid, were to
become unreliable for some reason. But I can say that
most sources point at Handley as being the first person
to patent and approach toward creating an uninterruptible power supply.
An early paragraph in the patent states quote, A specific
object of the invention is to provide apparatus for automatically
(43:56):
changing from a condition where a given source of electrical
energy is supplying an external circuit to a condition where
another source of electrical energy supplies the external circuit with
no interruption of electron flow in the external circuit end quote,
and I think it really drives home how bizarre the
(44:16):
language of patents can be. Now, the intended goal of
patent language is to provide a precise explanation of whatever
the proposed invention is intended to do. But it can
come across as very unnatural to me, kind of like
a robot wrote the whole ding ding durned thing. Now
you can read that patent if you like. It does
(44:38):
describe in rather obtuse terms, the general approach Hanley was proposing.
I've talked about Hanley's described invention would switch automatically from
a primary power source to a reserve power source in
the event of a loss of power. The patent number,
in case you are curious, is US one nine five
(44:58):
three six zero to A and that patent expired way
back in nineteen one. Patent expiration is important stuff, Like
when you patent an idea, you have protection for that idea.
Really it's it's more of an invention. You have protection
for that particular design of the invention and for the
(45:20):
life of the patent. You have intellectual property ownership rights
to that particular design, and if anyone wants to use
your design, they have to get your permission. Typically they
do that by licensing it, and then once the patent expires,
anyone is free to build a device that uses that
(45:42):
particular design or improve upon that design. It's fair game.
You don't have to pay licensing fees or anything once
that expires. So and it's an important component toward innovation. Well, Nick,
I hope you enjoyed that episode. It was kind of
fun to dive into all things electricity once more. And
(46:03):
like I said, there's still a whole lot I didn't cover.
I really didn't want to go too deeply into the
way home circuits work and those two hot wires that
come into us homes. Uh, it is a little bit
more complicated, It requires a lot more discussion, and I
figured that that was probably a little much for an
episode about, you know, surge protectors and uninterruptible power supplies.
(46:26):
But if you are interested in learning more about that,
let me know. Or if there's some other topic that
you would like to know more about in the tech world,
whether it's a company, a specific technology, a trend in tech,
away that technology is affecting our lives, anything like that,
let me know. You can reach out via Twitter. The
(46:47):
handle is tech Stuff H. S W and I'll talk
to you again really soon. Tech Stuff is an I
heart Radio product auction. For more podcasts from I heart Radio,
visit the i heart Radio app, Apple Podcasts, or wherever
you listen to your favorite shows. H
Welcome to tech Stuff, a production from I Heart Radio.
Hey there, and welcome to tech Stuff. I'm your host
Jonathan Strickland, Diamond executive producer with I Heart Radio and
I love all things tech, and today's episode is inspired
by a listener suggestion. Nick Sandor asked on Twitter, remember
(00:28):
the handle for the show is tech Stuff. H s
w if I had done an episode on uninterruptible power
supplies a k a. UPS, but not the UPS that
delivers packages, and also asked if I had maybe covered
surge protectors. So today we're going to expand that request
a little bit and talk about those and some circuit
(00:50):
breakers and fuses and power strips in general, and vampire power.
You know, I vant the suck your vaults. Wow. Okay,
that that sounded way less wrong in my head, but
let's dive in. First, let's talk about electricity and circuits
in general, including topics like voltage and current, because I
(01:14):
find that these concepts can be pretty easy for people
to mix up if they're not working with them regularly
or studying physics. So we use voltage to describe the
electric potential between two different points. Uh, if the electric
potential zero, if there's no difference between them. There's no voltage,
there's no there to make an electric current flow between
(01:39):
the two points, So everyone's just kind of cool and
hanging out where there are. And we're gonna use water
as sort of an analogy to talk about electricity quite
a bit in this episode. So in this case, imagine
you've got two clear beakers of water, and these beakers
have a little spigot at their base, right, So though
(02:01):
the water level is above where the spigot is, and
you've got the exact same amount of water in each speaker,
they're on a level table, so they're on the exact
same elevation with each other. There's no tilt or anything,
and you've got a clear tube connecting the end of
one spigot to the other spigot. Well, now that we've
(02:22):
got these two beakers their level, they have the exact
same amount of water in them. If we open those
spigots up, we're not going to expect to see water
flow from one to the other. Right there, pretty much
gonna stay in equilibrium because the water levels are the same.
There's no pressure there to move the water around. Two
(02:43):
points with zero electric potential are pretty much the same
sort of thing as these two beakers. All right, but
let's say we close the spigots on each beaker. Now
water is still trapped in the tube as well, it
can't go anywhere. And then we lift beaker one and
we placed it on top of a small stack of books,
(03:04):
So now it's at a higher elevation compared to beaker
number two. Beaker number two is still on the surface
of the table. Now, if we open up the two spigots,
what happens, Well, water from beaker one will start to
flow to beaker two. We will reach an equilibrium. Again,
but that's not really important for our understanding of voltage.
(03:26):
The point is, at the moment we open the figots,
the water will flow from beaker one to beaker two.
With voltage, a difference in potential will cause a current
of electricity to flow from one point to the other. Now,
because Ben Franklin made a fifty fifty shot and got
it wrong, we describe current as moving from a positive
(03:48):
charge to a negative charge. That positive moves to negative,
and we frequently describe electricity as a flow of electrons.
That's being a little simplistic, but it serves our purposes.
But electrons are negatively charged particles, so the electron flow
(04:08):
goes from negative to positive. Because remember opposite charges attract
and like charges repel one another. So the electrons move
from a point of higher negative charge to a point
of higher positive charge. So while we describe current as
positive charge moving toward negative, the actual electron flow is
(04:29):
negative towards positive. Yes, it is confusing. No, that's not
going to be the end of where things are confusing
in this episode, but stick with me. It's all understandable.
So the greater the difference in that negative and positive charge,
the greater the voltage. And you can think of voltage
(04:52):
as water pressure. If we're talking about that system we
were mentioning before, if we were to pour a lot
more water into beaker one, filling it up all the
way before we open up the spigots, you know, beager
ones at that higher elevation as well, we would actually
also be increasing the water pressure of the system in general,
(05:12):
and so we would see more pressure pushing the water
through to beaker number two. We see the same sort
of thing with electrical systems, and we measure this pressure
or voltage in volts, so you know, that's easy, and
that pressure metaphor also tells us how much work a
(05:32):
circuit can do. You know what kind of load can
you put on that circuit. Higher voltages can do harder work,
and a typical double A alkaline battery can offer up
one point five volts, which is a relatively small amount
In the United States. A wall outlet pushes out one
(05:53):
twenty volts, which is why you can run heavy appliances
using power from the wall, but a single double A
battery just won't cut it. Current is different. Current is
the rate at which electric charge flows past a specific
point within a circuit. This is the rate of flow
(06:14):
of electric charge, as opposed to voltage, which we can
think of as the energy per unit of charge. So
current describes how much electricity is flowing, even though that's
a little misleading, and voltage describes how much omph that
electricity has. We measure current in apps. Current needs voltage
(06:36):
to flow. If you don't have voltage, you don't have pressure,
you don't have current. It would be like our two
beakers that are side by side with that same level
of water. There would be no flow there either. Materials
that allow current to flow more easily are called conductors,
whereas materials that have high resistance to current flowing through
them are insulators. Now, pretty much every thing has some
(07:01):
level of electrical resistance, even the best conductors, at least
in conditions that most of us are familiar with. Now,
if you habitually cool down conductors to near absolute zero,
then you might be used to working with stuff that
has no electrical resistance a k a. Super conductors. But
for practical purposes, it's something we have to deal with
(07:24):
electrical resistance, and I also have to define circuits. So
a circuit is essentially a closed loop pathway that electricity
can follow. If you open any of that path, if
you break the line of that pathway, the electricity can
no longer flow through. And it's kind of like if
you were driving along a track. Let's say it's a
(07:46):
circular track, you know, like NASCAR racing, but part of
that track is actually underwater and you can't go through
that part. Well, you would start your race and then
you would hit this part where the water was and
you would have to pop and you couldn't actually continue.
Electricity is kind of similar. It has to have that
unbroken path in order for it to flow. So if
(08:08):
you break that path, the circuit no longer allows electricity
to flow. This is the whole basis of switches, right.
If you have an open switch, it means that you
have a broken path and the electricity cannot flow through it.
When you close the switch, you have completed that path
and now electricity can flow freely. So electricity will only
(08:30):
flow through a complete circuit. But that also means that
if you come into contact with a conductor, your body
could serve the same as a switch in a circuit.
You could close a circuit when you come into contact
with a conductor, and electricity will always attempt to return
to its source, and it will always follow the path
(08:53):
of least resistance. In a circuit, however, it will take
all available paths. So if you have let's ay you've
got a pathway in your circuit, and you divided into
three different lines, and you have different amounts of resistance
on each line, most of the current is going to
pass through the pathway that has the least resistance. You'll
still get some current going through the other pathways, but
(09:15):
it will be significantly less. So, if you come into
contact with a conductor and your body represents an area
of lower resistance, you're gonna take the brunt of that electricity,
and that's a that's not a good thing. I'll get
back into why that's not a good thing just in
a little bit. But components in a circuit can be
(09:36):
connected either in series, which means you have one right
after the other in a sort of single pathway, or
they can be connected in parallel, which means they be
in side by side individual pathways. When they're connected in series,
the same amount of current will flow through each component,
but the voltage drops from one component to the next.
(09:58):
In parallel, the voltage across each component will remain the same,
but the total current is divided between each pathway. So
it's it's an opposite situation from the series approach. Now,
when it comes to electrical shocks, amperage a gave the
current is really what we need to worry about, not
(10:20):
the voltages. You know, something we can ignore. But you
know you don't want to come into contact with a
high voltage line. Definitely don't do that. You should never
go near high voltage lines. Take it from electric six
danger danger high voltage. But it doesn't take a very
strong current to do serious damage. At around ten to
(10:44):
twenty milla amps, and a mill amp is one of
an amp. You would feel a zap of a shock.
At between twenty million amps, the current is strong enough
to deliver a powerful, painful shock and you lose control
of your muscles. You know, our bodies communicate and operate
(11:06):
on electrochemical signals, so electricity causes that to really go
hey wire. So at this level, if you were to
grab a wire that has between twenty and seventi five
milliamps a current running through it, you wouldn't be able
to let go. Your hand would seize around that wire. Now,
at around seventy five milliamps, your heart ventricles are affected
(11:30):
by this. They start to twitch uncontrollably, and I mean
that's seriously bad stuff. At one two d milliamps, it's
incredibly dangerous and a shock is often fatal at that
amperage above two hundred bill amps. Interestingly, your body's response
would be to clamp down so hard that you might
(11:51):
actually survive that shock because your heart is unable to
fibrillate to have these uncontrollable vibrations because your chest muscle
squeeze so hard it prevents your heart from fit relating. However,
you would also suffer really terrible burns and possibly damage
to your internal organs. So while you could survive that
(12:13):
kind of a shock, it would really hurt you. You
would be more likely to survive at that level, however,
than if you were to encounter a current of between
one two hundred milli apps that would be more likely
to be fatal. And when we talk about electricity, we
often talk about direct current versus alternating current. Direct current
(12:36):
is the easiest for us to understand. It's very easy
to draw and understand how this works. Electricity flows in
one direction only with direct current. It's like a one
way street. Batteries work this way. So a battery has
a negative terminal and a positive terminal, and electricity will
always flow from negative to positive, whereas the current is
(12:58):
going from positives and i aative, but we've covered that
with alternating current. However, it's like you're switching which terminal
is negative and which one is positive, and you're doing
that many times per second. The voltage actually kind of
moves in a sort of wave. It hits the peak
on one side. When terminal one is the most negative
(13:19):
it can be. In terminal two is the most positive,
it can be then it moves the other way as
the two terminals switch. So remember when I said that
the typical US household gets one volts delivered to outlets.
That is an alternating current. So in the US the
current alternates direction sixty times per second, So every sixty
(13:41):
seconds it goes one volts with the current flowing in
one direction and flips to one volts going in the
other direction sixty times a second. Now I say all this, However,
in reality, there is some variation in the amount of
voltage coming to various outlets in a home, and it
can vary to all sorts of stuff, like the gauge
(14:02):
of wire that was used to wire the house, the
temperature that the wires are at, the installation on the wires,
the distance of the house from the transformer on the street.
But you get the general idea. And moreover, electronics manufacturers
design products that can tolerate a small deviation from the standard,
whatever that standard might be in that particular country, and
(14:23):
different countries do have different standards. I'll be working with
the U S standard in this episode because I live
in the US. So the electricity goes over the power
grid and ultimately gets directed into your house or apartment
or whatever, which represents a new circuit, which in turn
is made up of smaller circuits, kind of wheels within wheels,
as it were. One other thing I should mention our
(14:47):
what's what's are a unit of power. And if you
take an electrical circuit and you multiply the voltage across
that circuit by the amps that are passing through the circuit,
you get watts. Watts equals volts times amps. Most of
our stuff actually runs on direct current, not alternating current.
(15:07):
So these devices that we plug into our walls typically
have what is called a rectifier. Uh. And if you
have devices that have a power brick, the power break
is your rectifier. Typically this converts the alternating current to
direct current. Usually have a much lower voltage as well.
You might wonder why we are even using alternating current anyway,
(15:29):
since most of our stuff is running on d C power,
wouldn't it make sense to just supply DC power instead
of having to convert it? Well, it all comes down
to transmitting electricity over great distances. More than a century ago,
there was a big debate about which approach was the
one to use. Thomas Edison wanted to go with direct current,
(15:51):
which would have required building out lots of power plants
to be close to the load. That is, you would
have to add power plants close to the places that
were actually using the electricity coming from those power plants.
Because it was really hard to send direct current of
sufficient voltage longer distances. You would have to have incredibly
thick cables and you would lose a lot of energy
(16:12):
in the form of heat waste. If you were really
pushing the voltage super hard, then the cables would heat
up to the point where they would just break under
the stress. So alternating current, which was championed by George Westinghouse,
could make use of electrical transformers, and with transformers you
can step up the voltage for long distance transmission, which
(16:35):
is much more efficient, and then you would have other
transformers at the other end to step down the voltage
once it got to wherever you were sending it. A
C power was more practical at the time and one out,
but it did mean having to use rectifiers to change
the A C T D C in order to make
practical use of it. With most appliances. If you're familiar
(16:56):
with the basics of circuits, you know about resistors, These
are elements that have a specific electrical resistance, you know,
a resistance to the flow of current, and they're used
to do all sorts of stuff. For example, the filament
in a light bulb is essentially a resistor which resists
the flow of current, and as current pushes its way
(17:17):
through anyway due to having a sufficient amount of voltage,
some of the electrical energy converts into heat, which heats
up the filament and ultimately causes it to glow. Well. Essentially,
all things you plug into a power outlet are acting
as a type of resistor in the circuit that is
your home's wiring. The appliance represents a constant resistance. Your
(17:41):
home is supplied with a constant voltage, so that means
the current is kept constant as well. Because all of
these things relate to one another. Now that's a good thing,
as good old Tom Harris wrote in a house stuff
works dot com article about circuit breakers. Quote, too much
charge flowing through a circuit at a particular time would
heat the appliances, wires, and the building's wiring two unsafe levels,
(18:05):
possibly causing a fire. End quote. So let's go ahead
and define a power strip. Now that we've got these
basics out of the way. A power strip is a
bunch of outlets that are mounted into a frame of
some sort. Now, while it might appear that these outlets
are in a series, like if you have a long,
thin powder strip, it looks like you've got a series
(18:27):
of outlets, they're actually wired in parallel. If you were
to take one of these apart and don't do that,
but if you were, you would see they're wired and parallel,
not in series. And if you remember, that means the
voltage is going to remain the same for every component
that gets plugged into that strip. That's important because otherwise
you would have a voltage drop if they were in series.
(18:50):
As you plugged more components into the strip, the voltage
would drop further down the series. And if you've got
a few components that require a hefty amount of voltage,
you could find yourself out of luck. The devices wouldn't
receive enough pressure to work. Now, while the voltage will
remain constant across the components plugged into a power strip,
and the resistance remains constant per component, adding more components
(19:14):
means increasing the load of current moving through the power strip.
So as you plug more stuff into a power strip,
the power strip has to supply more amperage. If the
power requirements of the components are super hefty, it could
mean overloading that specific circuit, which could lead to some
of those really bad outcomes like an electrical fire. And
(19:35):
that's where circuit breakers come in. I'll explain them more
in just a second, but first let's take a quick break. Okay,
so without circuit breakers or fuses, there would be no
fail safe to prevent someone from overloading a home electrical
(19:59):
circuit and causing wires to heat up enough to melt
or cause a fire. So thankfully we do have these
elements to help keep us safe as we use electricity.
Let's start with fuses, because they are pretty simple to understand.
A fuse has a thin wire inside that's kind of
like a filament to a light bulb. Fuses are designed
(20:20):
to handle a certain amount of current within a circuit.
If the fuse receives more than that allotted amount of
current based on the type of fuse you're using, then
the electrical energy that's running through that thin wire will
cause it to heat up rapidly and it begins to disintegrate.
It burns through that cuts off the electrical circuit. We
(20:42):
have now cut off that pathway broken it. But the
bummer of the sort of approach is that when that
does happen, you have to replace the fuse. They are
a one use item. Uh so they do protect your
home in the case of a increase in current, which
could be a real problem, but it means also that
(21:03):
once that does happen, you have to go out and
replace the fuse and the fuse box. I used to
live in a house that still had a fuse box
and occasionally we'd have a fuse go out and that
was a real hassle. I mean, just finding the right
fuse to go in the right section was was something
of a challenge at times. Circuit breakers are way easier
from an end user standpoint, and it typically involves opening
(21:26):
up a panel and flicking a switch that has been
turned off to on. So when you flip the switch
to on, it completes a circuit. It allows electricity to
flow through, but if the current running through that circuit
exceeds a certain amount, it trips the switch, so it
turns off. And there's actually a couple of different ways
this can be done, but one of them is using
(21:49):
an electro magnet. The current causes the electro magnet to
generate a magnetic field, and if the current peaks, if
it gets too strong, that magnetic field comes strong enough
to pull a metal lever and mechanically move it to
a different position, which actually causes the switch to flip off.
(22:10):
It's the power of magnetism that pulls the switch into
the off position. It's incredibly clever because that only happens
if the electrical current is strong enough to create that
magnetic field in the electro magnet. So very ingenious design.
Now that's a very high level look at circuit breakers.
It's also not the only way that circuit breakers can work.
(22:33):
But I want to segue over to surge protectors because
that was the actual area of interest that I was
asked about. So circuit breakers are all about cutting off
a circuit once the current becomes too strong. Surge protectors
are about protecting against a quick increase in voltage. So
this is about finding a way to deal with a
(22:54):
sudden increase in electrical pressure. If you like surges, don't
have to laugh very long before they are a problem.
If you get a super fast jump and voltage that
only lasts for a nanosecond or two, we call that
a spike, But if it lasts three nanoseconds or more,
(23:14):
it's a surge. But a nanosecond is one billionth of
a second. So yeah, surges can be quick, far faster
than we can perceive, though we definitely can perceive the
consequences of a surge. Now, if you have something plugged
into an outlet and the outlet experiences a surge, it's
(23:34):
kind of like if you were to have a water
hose connected to a spigot and suddenly that spigott forces
way more water through the hose than it can handle.
The hose itself can burst if there's too much water
pressure inside of it. So voltage surges can cause wires
to melt or make devices work way harder than they
(23:54):
are supposed to. You know, devices are meant to work
at a certain voltage. There you can in add more voltage.
You could create more voltage and thus make the device
work harder than it was intended, but that's not a
great idea. So, for example, the device you've got plugged
into a wall has a motor in it, then the
motor may suddenly operate at a speed much higher than
(24:17):
it was meant to and this might not result in
immediate failure, but it definitely adds to the wear and
tear on a device. It can also be a safety issue,
so you want to avoid surges. A surge protector deals
with a rapid increase in voltage by directing excess current
into the wall outlets. Grounding wire and a grounding wire
(24:40):
is kind of what it sounds like. It's a safety
wire in the outlet that ultimately connects to earth. So
under normal circumstances, this wire does not carry any electricity.
It's it doesn't hold a current. Under normal operating conditions,
it has very low resistance, but current does not flow
(25:01):
through it. The grounding wire is there to serve as
an alternate pathway for current to flow in the event
that something has gone wrong. By the way, there's also
a grounded neutral conductor sometimes called a ground wire or
grounded wire. So you have a grounding wire and a
grounded wire, and yeah, that makes stuff gets super confusing
(25:24):
because it's very easy to mix up grounding wire and
grounded wire. So let's step back for a second, and honestly,
we can get around this confusion if we just call
it the neutral wire in the first place. So at
bare minimum, if you want a circuit, you need two wires.
And let's just imagine a very simple circuit with a
(25:45):
battery and a light bulb and a pair of wires.
So you've got a wire that connects the negative terminal
of the battery where the electrons are coming out to
the bulb, and this is the hot wire. It is
carrying electrons to the circuit load. The load being the
component that requires electricity to work, and this example it's
(26:05):
the bulb. The wire that connects the bulb to the
batteries positive terminal is called the neutral wire. This is
how the electrons returned to the battery and complete the circuit.
So if you don't have that neutral wire connecting back
to the battery, you don't have a circuit. No electricity
is flowing, the lamp is going to stay off. It's
only when you complete the circuit by adding this neutral
(26:28):
wire that you are going to have any light on
that that bulb. So with an outlet, the hot wire
carries electricity to the load and the neutral wire carries
the quote unquote used electricity back. So the neutral or
grounded wire is actually carrying an electric current under normal
operating conditions, unlike the grounding wire, which is a safety precaution. Now,
(26:52):
this actually gets more complicated because in the US you
actually have two hot wires coming in circuits and one
neutral wire coming in, and then you have the grounding
wires all part of the outlets that you're using. But
really that merits its own podcasts, so I'm not gonna
go into it too much. It's all has to do
(27:12):
with the fact that we're relying on alternating current, but
it doesn't really matter for the rest of this episode.
So the important thing to remember is that the grounding
wire terminates ultimately in the ground itself, in the earth,
and it allows the circuit to discharge excess electricity in
special circumstances. So, for example, if the hot wire in
(27:33):
a circuit, the one that's carrying electricity to a load,
were to make contact with something other than the intended load,
like say the casing around a light socket, the ground
wire would represent a low resistance pathway for electricity to
flow back out rather than for things to start heating
up and becoming a real problem, because otherwise the casing
(27:56):
is going to act like a resistor. So in a
surge protector, you've got an element that connects the hot
wire to the grounding wire. But you have to be
careful about this, right. You don't want to have just
a simple connection from hot wire to groundwire because then
the electricity is just gonna flow straight to the ground wire.
It's not gonna do any work. So one example of
(28:18):
this is a thing called a metal oxide verista. This
is made up of a piece of metal oxide that
sandwiched between two semiconductors, and the semiconductors have special properties
that determine how they perform within a circuit. Semiconductors typically
can act as either a conductor or an insulator depending
on specific circumstances. In the case of this metal oxide verista,
(28:43):
we would look at the voltage. So at low voltage,
the semiconductors have a very high electrical resistance, and because
electricity wants to follow the path of least resistance, that
electricity is just gonna keep on going past the verista.
It's gonna be like not interested. But at higher the
normal voltage, the semiconductor's resistance drops dramatically. Now electricity can
(29:07):
flow through that pathway easily because there's very low resistance,
so it means current is going to pass through the
hot wire, through the verista and to the grounding wire,
which ultimately terminates in the ground itself, and that discharges
the extract current and returns the voltage in the hot
wire to normal, And so the semiconductors, once the voltage
is normal, will return to their normal resistance and electricity
(29:31):
will follow the usual pathway. What this means for your
electronics is that if there's a surge in voltage, the
extra pressure gets relieved through this grounding wire and doesn't
make it to the devices that you're plugged into the
surge protector itself. It's kind of like a pressure relief
valve in a water pressure system. Now, the metal oxide
(29:53):
verista is just one type of surge protector. There are
lots of others, such as gas discharge arrest rs. I
love the names for these. These have a gas tube
that are that's filled within the inert gas and this
gas can conduct electricity, but its conductivity is variable, so
at low voltages it's not a very good conductor. It's
(30:15):
akin to having a high resistance. At higher voltages, however,
the gas inside the tube begins to ionize, it begins
to release some electrons, so you have some free flowing
electrons in the gas that allows current to flow through
the gas more readily, and so again it acts kind
of like a pressure release. Both the Varista and the
(30:37):
arrestor are based off parallel circuit designs, but you can
also have surge protectors that use series circuit designs. And
if you remember, components that are connected through series have
a lower voltage as you add more loads more components.
These protectors don't bypass surges the way the parallel ones do.
(30:59):
They suppress surges. Oh and and for the parallel based designs,
there's another important thing to keep in mind. These protectors
work by sending that excess electricity to the homes ground wire.
So home needs a grounding wire, like there needs to
be a wire that actually extends down into the ground.
Without that grounding wire, a surge protector wouldn't be any
(31:20):
help because there would be no pathway to serve as
that pressure release system. The US outlets that have three slots.
When you see a three slot outlet in the wall,
those are supposed to be grounded outlets. The D shaped
rounded slot, the the hole in the bottom or sometimes
the top, depending on how the outlet has been installed.
(31:41):
That's the one that connects to the home or buildings
ground wire, or at least it's it's supposed to. Now
let's talk about them buyers, or rather vampire power. So
a lot of our devices don't really turn off when
we turn them off, at least they don't shut down completely. So,
(32:02):
for example, I have a computer mouse that is connected
to a second computer at my desk, and that second
computer is currently turned off, Yet my computer mouse has
led lights that are still lit. Now there's no battery
inside my computer mouse. Clearly my computer mouse must still
be drawing power from the computer, but the computers off,
(32:23):
So what gives Well, my computer, like a lot of electronics,
is actually still drawing some power even when it is
turned off. Televisions tend to be the same way, printers
to Really, a lot of stuff has a type of
standby power mode, so that even when you shut them off,
they're only what you know, Miracle Max would call mostly off,
(32:47):
there's still slightly on. And there are a few reasons
for this, but the big one is that it's very convenient.
It means the devices have a shorter startup time when
we power them on. So when you grab they're clicker
and turn on the old picture box, you don't want
to wait for them hamsters inside to get up to
run speed. I'm sorry I allowed an old prospector to
(33:10):
write that last bit. What I meant to say is
we don't really like a delay between when we turn
something on and when it's actually usable. So standby power
is a kind of cheap mode to cut down on
the weight times we have. So if you power something
on and you're waiting for it to warm up, that's
really frustrating. Standby power helps cut down in that weight time.
(33:32):
Smart power strips are meant to detect when the device
is off but attempting to draw a standby power, and
these power strips cut off the source of that standby power,
thus ensuring that the device is well and truly off.
It's not sipping electricity, and that means using less juice
during the month, which also means a lower power bill.
(33:53):
Is it significant Well? Estimates vary, but analysts say that
stand by power consumption can make up but wween five
and ten percent of a household's energy consumption, so it's
definitely enough to be noticeable. It might be around a
hundred bucks a year in savings, so it's it's you know,
it's not nothing. Smart power strips have some extra circuitry
(34:15):
in them compared to your run of the mill normal
power strip. They still represent a group of outlets that
are mounted in parallel because you still want to make
sure you're not causing a voltage drop from one device
to the next as you plug them in. But they
also contain circuits that monitor a drop in power consumption,
which would indicate a transition into standby power mode, and
(34:35):
at that point, the power strip would break the circuit
to the device, cutting off power. There are different ways
to do this. One common one is to have a
master outlet that then determines whether or not power gets
supplied to some control outlets. This is easier to understand
if I actually use an example. So let's say I've
got a home entertainment system and that consists of my television.
(34:59):
I've got a surround sound system, I've got a video
game console, I've got a Blu ray Player, and I've
got a cable box. Now, let's say I always want
to have the cable box running. Let's say it's also
my DVR and stuff, so I plug that into an
outlet on my smart power strip that is always hot,
meaning it's always going to have power supplied to it
(35:21):
no matter what that outlet is, just like if I
had plugged it straight into the wall. But the surround
sound system, the video game console, and the Blu ray
player are really only useful to me if the television
is also on, So I plugged those three devices into
the control outlets in my smart power strip. The control
(35:43):
outlets take a queue from the master outlet that's where
I plug in my TV, So TV goes into the
master outlet, Blu ray players, surround sound system, video game
consoles into the control outlets. The circuits in the smart
power strip will detect when the TV is on because
they detect an increase in power consumption, So when that happens,
(36:03):
the power strip also allows power to flow to the
devices that are plugged into the control outlets. But if
I turn off my television, the drop in power consumption
tells the power strip that it no longer needs to
supply electricity to those control outlets. So in that case,
the Blu ray player, of the surround sound system, the
video game console, all go dark, they can't sip any
(36:25):
phantom power. That makes sense, right, I mean I can't
use those devices unless the television is on. Anyway, when
we come back, will transition over to uninterruptible power supplies.
But first let's take another quick break. Sometimes the stuff
(36:49):
we count on just asn't dependable. Like electricity, there are
times when the power goes out. Maybe a transformer is
over did which can be pretty darned spectacular, not to
mention loud and dangerous. Maybe something has broken a power
line leading to your home. Whatever the root cause, the
(37:11):
effect is the power goes out in your house, and
that can potentially damage certain electronic devices if they happen
to be plugged in and active at that moment, like computers,
And that's where an uninterruptible power supply or UPS comes in.
These are systems that are intended to supply electronic loads
with sufficient power to continue operations at least for a
(37:33):
short while in the event of a power outage. For
the type that the average person like you or me
might be dealing with. It may just be something that
lasts long enough for us to you know, save whatever
we were doing on the computer and then shutting it
down in a controlled power off cycle. It's not something
that can supply power forever, but rather work as a
(37:56):
type of stop gap while you wait for your electricity
service to come back on. There are a couple of
versions of these uh. In fact, there's really three main types,
but I'm really only going to cover two of them.
A standby UPS is sort of UPS is just waiting
in the wings, so in the event of a power outage,
(38:18):
then it kicks on, using a rechargeable battery as the
power source. These types of UPS systems typically have some
sort of switch to handle the change from supplying power
from the outlet to the devices to switching over to
supplying power from the onboard UPS battery. With continuous UPS devices,
(38:39):
the stuff you plug into the UPS is always drawing
power from the battery, but in turn, the battery is
in a constant state of recharging, drawing power from the
wall outlet. So if the power from the outlet goes out,
the computer or you know, whatever you have plugged into
the up US just keeps drawing power as it always
(39:03):
had because it's always taking power from the battery. It's
only when the UPS battery itself runs out of charge
that you have a problem. But again, the typical operating
procedure here is to use the time that you have
to take care of saving stuff and shutting down your
electronics safely. Um. Granted, it's a different story if you're
talking about industrial uses. In either case, the UPS has
(39:26):
to do something really interesting and it also can seem
a little backward. Okay, remember when I said most of
our devices run on direct current d C, so they
have to have what's called a rectifier to convert the
incoming alternating current from the wall sockets into d C
power that the device can use. Well, batteries if you
(39:50):
recall supply direct current d C power, not alternating current. However,
our devices still need to accept alternating rant even though
they ultimately run on direct current. So this means the
direct current from the battery in the UPS has to
convert into alternating current so it can be sent onto
(40:13):
the devices, which then use rectifiers to convert the alternating
current back into direct current. What a way to run
a railroad. So a rectifier takes a C turns it
into d C. We call devices that do the opposite,
that take DC and turn it into a C. Inverters.
So the UPS has an inverter to take the d
(40:35):
C power out of the battery converted to a C
which goes to the devices rectifier to get converted back
into d C. And to make this even more complicated,
rechargeable batteries need a direct current to recharge, so that
means the UPS actually has its own rectifier. So the
UPS has a rectifier. It takes a C coming from
(40:56):
the wall right, the a C goes to the directive
fire gets converted into d C. That DC power charges
the battery on the UPS. Then from the battery there's
the inverter to convert the d C into a C.
And at this point I really wish Thomas Edison could
have cracked the problem of long range power transmission using
(41:18):
direct current because it really would have simplified things a
ton on the user end. Now, I like to think
of rectifiers and inverters as something Luke Skywalker would really
be interested in. After all, he was really looking forward
to going to Tusky Station and picking up some power converters.
And if you don't get that reference, you need to
watch Star Wars a New Hope. If you're shopping for
(41:41):
UPS systems, chances are you're going to be looking at
stand by UPS devices. They tend to be much less
expensive than continuous UPS devices, and they work pretty well
for most of us. If you oversee something that's really
mission critical, like a server room or something that's a
different story. In those cases, the need for a stable
source of power is enough to justify the higher cost.
(42:02):
Your typical UPS will have some sort of way to
signal that the power has switched over to the battery.
Usually it's a beeping noise, and that gives you the
opportunity to get stuff you know powered down in a
controlled way, and they may also require you to reset
a UPS once power has been restored to the home
or building. I have often worked in offices where you
(42:25):
could hear a beeping going off and realize that someone's
UPS had tripped, and you need to find which one
it was and reset it, and it's a fun game
of hide and seek or lose your sanity. Now, normally
I would have jumped right into history at the beginning
of an episode, but I figured it would make more
(42:46):
sense to kind of tack it on at the end
of this one, to be kind of a little bit
of just bonus tidbit information sort of a pub trivia
kind of bit of info. So, way back in nineteen
thirty two, a guy named John J. Hanley filed for
a patent titled Apparatus for Maintaining an unfailing and uninterrupted
(43:09):
Supply of Electrical Energy. Now, I cannot say for certain
he was the first person to come up with this idea.
In fact, I think it's safe to say that the
idea was one that was forming in a lot of
places around the same time. Because we were becoming more
dependent upon electricity, people saw the need for there to
be some way to have a dependable source of electricity
(43:32):
in case our primary source, the power grid, were to
become unreliable for some reason. But I can say that
most sources point at Handley as being the first person
to patent and approach toward creating an uninterruptible power supply.
An early paragraph in the patent states quote, A specific
object of the invention is to provide apparatus for automatically
(43:56):
changing from a condition where a given source of electrical
energy is supplying an external circuit to a condition where
another source of electrical energy supplies the external circuit with
no interruption of electron flow in the external circuit end quote,
and I think it really drives home how bizarre the
(44:16):
language of patents can be. Now, the intended goal of
patent language is to provide a precise explanation of whatever
the proposed invention is intended to do. But it can
come across as very unnatural to me, kind of like
a robot wrote the whole ding ding durned thing. Now
you can read that patent if you like. It does
(44:38):
describe in rather obtuse terms, the general approach Hanley was proposing.
I've talked about Hanley's described invention would switch automatically from
a primary power source to a reserve power source in
the event of a loss of power. The patent number,
in case you are curious, is US one nine five
(44:58):
three six zero to A and that patent expired way
back in nineteen one. Patent expiration is important stuff, Like
when you patent an idea, you have protection for that idea.
Really it's it's more of an invention. You have protection
for that particular design of the invention and for the
(45:20):
life of the patent. You have intellectual property ownership rights
to that particular design, and if anyone wants to use
your design, they have to get your permission. Typically they
do that by licensing it, and then once the patent expires,
anyone is free to build a device that uses that
(45:42):
particular design or improve upon that design. It's fair game.
You don't have to pay licensing fees or anything once
that expires. So and it's an important component toward innovation. Well, Nick,
I hope you enjoyed that episode. It was kind of
fun to dive into all things electricity once more. And
(46:03):
like I said, there's still a whole lot I didn't cover.
I really didn't want to go too deeply into the
way home circuits work and those two hot wires that
come into us homes. Uh, it is a little bit
more complicated, It requires a lot more discussion, and I
figured that that was probably a little much for an
episode about, you know, surge protectors and uninterruptible power supplies.
(46:26):
But if you are interested in learning more about that,
let me know. Or if there's some other topic that
you would like to know more about in the tech world,
whether it's a company, a specific technology, a trend in tech,
away that technology is affecting our lives, anything like that,
let me know. You can reach out via Twitter. The
(46:47):
handle is tech Stuff H. S W and I'll talk
to you again really soon. Tech Stuff is an I
heart Radio product auction. For more podcasts from I heart Radio,
visit the i heart Radio app, Apple Podcasts, or wherever
you listen to your favorite shows. H
TechStuff News
Hosts And Creators
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Karah Preiss
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