Help with electricity

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Final Approach
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Ben
Could someone who is patient please explain as simply as possible the following? (My EE grandpa tried to several times, and I did get the concept, but not a real understanding).

Volts

Amps

Watts

How does the alternator work with the battery

How does a generator work with a battery

I know this is simplistic. And again, I could answer this myself; but I still don't understand fully how this all works.

Thanks in advance!
 
Could someone who is patient please explain as simply as possible the following? (My EE grandpa tried to several times, and I did get the concept, but not a real understanding).

Volts

Amps

Watts

How does the alternator work with the battery

How does a generator work with a battery

I know this is simplistic. And again, I could answer this myself; but I still don't understand fully how this all works.

Thanks in advance!

Think of electricity as water: Volts are pressure, Amps are volume and Watts are total quantity, the product of volume times pressure over a period of time.

The alternator and generator in relationship to the battery work the same, they provide electrons at a pressure slightly higher than that of the battery. The battery is the same as the city water tower. It holds the electrons ready to go using the tanks 'head pressure' of 13.2 volts when filled to the top. Same as with a water tower, it'll lose some pressure as the tank drains, but since the tank is so high, it will still have pressure when nearly empty; a battery at 11.5 volts is basically empty even though the pressure is still 80% of what it should be. The alternator and generator are pumps that refill the battery/tank with energy from the engine.
 
Man, Henning has as good a simple explanation as I can imagine.
 
No worries, I'm not that bright, I have to take things to basics.
 
:yeahthat:

Volts (voltage) (E) = Potential. Stored energy ready to be used.

Amps (amperage) (I)= Flow of electrons from one atom to another, (current).

Watts (wattage) (P) = The amount of power or rate of work being generated as a result of Potential and Flow. You need potential to get flow and you need them both to get power or watts.

P=ExI

Remember, in order to have current (flow) you need a conductor and that conductor will produce resistance to the flow measured in Ohms (R).

The conductor can be water, metal, gas, skin! :yikes:

It gets more complicated when you consider AC, inductive or capacitive loads, etc. But you wanted simplicity. :rofl:
 
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Henning covers Direct Current basics well with the water distribution analogy.

I've seen that one taken even further with conductors as "pipes" and it starts to fall apart at things like short-circuits where the "pipe" destroys itself... since real-world pipes are usually burst by pressure (volts) and that's not the single mechanism that's destroying an electrical conductor.

The concepts work to some extent for Alternating Current but not quite. New behaviors come into play.

That link to NEETS, that's their Module 1. There's 24 modules there. A little light bedtime reading.

E=IR !!! ;)
 
An electrical circuit requires a source of electricity, something to conduct it, and something upon which it can act (resistance).

Your source in the aircraft is the aircraft battery, and the alternator/generator. The battery is simple; it has a positive terminal and a negative terminal. Electricity flows from the negative terminal to the positive (contrary to popular belief). The difference in electrical potential between the two is voltage. Batteries are typically either 12 volt, or 24 volt. A volt is nothing more than a measure of the force trying to get from one terminal to the other, when the values of the two are compared.

As another poster noted, volts can be compared to pressure in a hose. Volts is the force pushing the water through the hose.

Amps or amperes, is a value which represents the current or flow of electricity. Think of it as the amount of water flowing through the hose, and think of it in terms of how it could hurt you or drive a motor. More current or more flow (more amps), the more it can hurt. High volts with few amps, not so bad, but high volts with lots of amps; that could hurt.

Watts could be thinking of what the electricity is doing or capable of doing. Think of a 60 watt lightbulb. More watts, more capability.

Batteries are rated in ampere/hours. A strong amp/hour battery is capable of sustaining more current for a longer period of time than a smaller amp/hour battery. Batteries are also rated in terms of cold cranking amps, which is what they can put out for a shorter period of time, and it has application with putting a heavy load on the battery, such as during the engine start.

All alternators and all generators put out alternating current. That means that electricity changes direction in a wire repeatedly. Generators use devices inside or outside the generator which filter the electricity to allow it to go just one way through a wire, just like the electricity that a battery puts out. When the electricity travels one direction through a wire, it's called "DC," or Direct Current. Sometimes you'll see electrical value written as "VDC," meaning volts of direct current.

Conversely, an alternator puts out AC current, which keeps switching direction in the wiring. In most light aircraft, this isn't useful for the simple electrical system, and small devices called diodes are used as electrical filters, allowing only DC to the aircraft sytem. Large aircraft use AC electricity (Alternating Current: same as you get out of the electrical outlet in your wall) for most components, with some parts of the system converted to DC electricity by "rectifying," which is a lot like straining the electricity to make it go just one way in the wire.

AC electricity is a little harder to control, especially when several sources of electricity are used at the same time (multiple alternators, for example). As long as DC electricity has the same voltage, it can all be sent to the same wire or same devices. DC is simpler to use, and is the most common in light airplanes. Aircraft systems are usually either 14 volt, or 28 volt. The batteries are 12 volt or 24 volt, and the slightly higher alternator/generator output is used to help charge the battery.

Think of the battery as an electrical piggy bank. It stores electricity. It also helps act as an electrical shock absorber. If a sudden change in electricity occurs in the airplane, the battery helps absorb that electrical spike, and creates more even flow through the aircraft system.

Ammeters show the draw on the battery; a positive value or close to neutral value shows that the alternator is doing it's job. A negative value shows that the battery is being discharged, and isn't being charged by the alternator.

Voltmeters tell you what the highest voltage is in the aircraft electrical system. A value lower than the nominal battery voltage tells you that the battery isn't fully charged, or is being drawn down. A voltage higher than battery voltage tells you that more electricity is available in the system than the battery puts out, which tells you that the electrical system is working, and implies that the battery is being charged.

Too high a charing rate isn't good; it tends to make batteries hot. This can be seen sometimes if a battery is really drawn down, such as if one really cranked on the starter, trying to get the engine to turn over. If the battery is depleted by the time the engine starts and the electrical system is engaged (alternator turned on), the sudden rush of electricity to the battery as it's recharged can make it hot. Some types of aircraft batteries, especially Nickel-Cadmium (NiCad) can experience a "thermal runaway" in which they keep getting hotter and hotter and have an internal breakdown which can melt the battery. In most light airplanes, these types of batteries are not usually used. Instead, the same type of battery that you find in your car, a lead acid battery, is used.

Your aircraft usually uses what's called a "negative ground" system. Because electricity flows through a conductor (wire, etc), with end connected to the negative terminal of the battery and one end connected through the positive terminal, aircraft use a simple method of flowing electricity. The frame, fuselage, or certain parts of the aircraft are connected to the negative terminal on the battery. This is called the "ground," or sometimes the "earth." The electrical components of the aircraft are hooked to the positive terminal through wires, switches, circuit breakers, etc. The other side of the electrical components is hooked to the frame. This reduces the wiring in some cases, and simplifies the way the electrical system is set up. Your car uses this method, too.

Electrical systems in the aircraft are hooked to metal bars that feed a number of wires. Each of these bars or groups of bars is called a "bus." Light aircraft often only have one or two busses, whereas large or complex aircraft may have dozens. These are basically like outlets in your house. Electricity goes to the bus, and then various components get their electricity off the bus. You'll see this term often used in aircraft flight manuals in the systems descriptions.

Circuit breakers exist in circuits (a circuit, remember,is the electrical source, the wires that conduct it, and the motor, light, or other resistor that's in the circuit) to protect the wiring in a circuit. These breakers are simple switches that usually open automatically if too much electricity is forced through the wiring. The circuit breakers are safety devices that get warm or trip magnetically, and open the circuit to stop the flow of electricity.

Understanding your electrical system is important: it lets you know how to recognize what's wrong, what's right, and what to do about it, and how to operate it safely and efficiently. In most cases, there's little to do as a pilot, but if system components fail (such as a generator failure), then knowing how to reduce the electrical load on the battery by knowing which components use the most electricity (lights transponder, etc), then you can make your electricity last longer. If you know that your flaps are electrical, you might consider not landing with the flaps, in an electrical failure situation, because if you need to go around, you might not have enough electricity to retract the flaps. If you have a retractable gear airplane, you might know that a failure of the gear to extend or retract might be a hot solenoid, and shutting off the electrical for ten minutes might fix the problem.

Knowing your system and how it works, unique to the aircraft you're flying, helps you know how to handle problems, and how to handle it when it's functioning properly.

Most light aircraft using piston engines use magnetos. These keep producing their own electricity and will keep the engine running even if the battery goes dead or gets shut off, and even if there's no power from the alternator/generator. These are simple devices which produce electricity for the spark plugs, and then distribute that electricity to the spark plugs. They are distributors just like you have in your car, but differ in that they can also produce the electricity; your airplane will have two each supplying one of two spark plugs in each cylinder, to help ensure that your engine will keep firing away even in the event of an electrical failure, or a failure of a single magneto.
 
Being a yacht captain, how else would you expect Henning to explain it, if not with water as a reference? :D
 
It's basically magic. So we need Doug Henning as well as our own pilot Henning to understand it.
 
Good job, Henning.

Alternator and generator serve the same function, they charge the battery by producing electricity at a higher potential (volts) than the battery so the electricty flows into the battery and "refills" it with electrons (so to speak).

The main difference being that an alternator produces AC - alternating current, hence alternator, and uses diodes, electrical one-way valves, to convert the AC to DC, direct current, that the engine and battery use. A generator produces DC. An alternator requires an "exciter current" which must be provided from an external source so it will not work with a totally dead battery while a generator does not require any outside energy and produces electricity any time it turns.
 
The main difference being that an alternator produces AC - alternating current, hence alternator, and uses diodes, electrical one-way valves, to convert the AC to DC, direct current, that the engine and battery use. A generator produces DC. An alternator requires an "exciter current" which must be provided from an external source so it will not work with a totally dead battery while a generator does not require any outside energy and produces electricity any time it turns.

Very interesting...I'm good with DC theory (spent 8 years as a telephone technician) AC theory...meh...but I never knew this about the difference between alternators and generators...cool:D
 
Very interesting...I'm good with DC theory (spent 8 years as a telephone technician) AC theory...meh...but I never knew this about the difference between alternators and generators...cool:D

Cool. Here is a little bit from Wikipedia about why we now use alternators:

Early motor vehicles until about the 1960s tended to use DC generators with electromechanical regulators. These have now been replaced by alternators with built-in rectifier circuits, which are less costly and lighter for equivalent output. Moreover, the power output of a DC generator is proportional to rotational speed, whereas the power output of an alternator is independent of rotational speed. As a result, the charging output of an alternator at engine idle speed can be much greater than that of a DC generator.
 
You sure it's not the flow of holes?



The water has to have some mineral content though.

Good observation. Actually current flow is the transfer of electrical charge from one electron to another and not a flow of electrons in a wire. Electrons moving at close the speed of light would require a higher energy level than that carried by the electrical current iself. It is similar to sound in air. On a sound wave the air molecules do not move at the speed of sound but rather touch each other to transfer the sound kinetic energy at the speed of sound.

José
 
Very interesting...I'm good with DC theory (spent 8 years as a telephone technician) AC theory...meh...but I never knew this about the difference between alternators and generators...cool:D

AC is just like DC except is goes back and forth.

Imagine you keel haul a person. You tie a rope to the person on one side of the boat that goes over the side, under the boat and back up to the other side of the boat. Now you push the guy over the side and pull him up the other side dragging his body over all the barnacles and crap stuck to the bottom of the boat. They come up bloody and often die as a result.

That's DC.

If you did the same but kept a rope tied to him from the original side and when he got to the bottom of the boat you started a 'sawing' motion dragging him back and forth scrubbing the bottom of the boat with the guy that would be way worse for the guy.

That's AC.


Btw, the ropes are the current, how big the guys are pulling the rope is the Volts and the barnacles are the resistance.


I'm going for obscure here. Sorta makes the point though...

; )
 
AC is just like DC except is goes back and forth.

Imagine you keel haul a person. You tie a rope to the person on one side of the boat that goes over the side, under the boat and back up to the other side of the boat. Now you push the guy over the side and pull him up the other side dragging his body over all the barnacles and crap stuck to the bottom of the boat. They come up bloody and often die as a result.

That's DC.

If you did the same but kept a rope tied to him from the original side and when he got to the bottom of the boat you started a 'sawing' motion dragging him back and forth scrubbing the bottom of the boat with the guy that would be way worse for the guy.

That's AC.


Btw, the ropes are the current, how big the guys are pulling the rope is the Volts and the barnacles are the resistance.


I'm going for obscure here. Sorta makes the point though...

; )

Interesting analogy. That is a new one for me :D
 
Cool. Here is a little bit from Wikipedia about why we now use alternators:

Early motor vehicles until about the 1960s tended to use DC generators with electromechanical regulators. These have now been replaced by alternators with built-in rectifier circuits, which are less costly and lighter for equivalent output. Moreover, the power output of a DC generator is proportional to rotational speed, whereas the power output of an alternator is independent of rotational speed. As a result, the charging output of an alternator at engine idle speed can be much greater than that of a DC generator.

I switched the 310 from generators to alternators before I ever flew it lol. He was chasing a problem with the charging system and I said "I'll buy the alternators, you install" "Done". Screw generators on recips, not worth it. From my understanding turbines still use generators (no real speed fluctuation issues) as they're double set to act as the starter motors as well.
 
AC is just like DC except is goes back and forth.

Imagine you keel haul a person. You tie a rope to the person on one side of the boat that goes over the side, under the boat and back up to the other side of the boat. Now you push the guy over the side and pull him up the other side dragging his body over all the barnacles and crap stuck to the bottom of the boat. They come up bloody and often die as a result.

That's DC.

If you did the same but kept a rope tied to him from the original side and when he got to the bottom of the boat you started a 'sawing' motion dragging him back and forth scrubbing the bottom of the boat with the guy that would be way worse for the guy.

That's AC.


Btw, the ropes are the current, how big the guys are pulling the rope is the Volts and the barnacles are the resistance.


I'm going for obscure here. Sorta makes the point though...

; )

I prefer running them quickly back feet first through the props. Make it take no more than 20 seconds so they're conscious as the blades dig through them. Make sure you secure the bitter end of the line short enough so you don't get it fouled.
 
I prefer running them quickly back feet first through the props. Make it take no more than 20 seconds so they're conscious as the blades dig through them. Make sure you secure the bitter end of the line short enough so you don't get it fouled.

Um, and that has exactly what to do with electricity? :D
 
Good observation. Actually current flow is the transfer of electrical charge from one electron to another and not a flow of electrons in a wire. Electrons moving at close the speed of light would require a higher energy level than that carried by the electrical current iself. It is similar to sound in air. On a sound wave the air molecules do not move at the speed of sound but rather touch each other to transfer the sound kinetic energy at the speed of sound.

José

Actually, an electron never moves its charge, the charge is intrinsic to the electron. What occurs, to my understanding, is that, in a conducting material, the electrons are not tightly bound to their particular nuclei but exist in cloud, so to speak. When we add electrons to the cloud in one area and remove them from another area, that causes a potential difference and the electrons flow to the relative "vacuum", the relative positive charge (less electrons to balance the protons in the nuclei) side. The same theory that, as Henning shows, motivates water to flow. The same as what makes weather, high and low pressure, high and low potential
 
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Here is the above concept from Wikipedia. A bit more technical but not too bad:

Valence electrons and electrical conductivity

The valence electrons are also responsible for the electrical conductivity of elements, which may be divided into metals, nonmetals, and semiconductors or metalloids.
Metals or metallic elements are elements with high electrical conductivity in the solid state. In each row of the periodic table the metals occur to the left of the nonmetals and thus have fewer valence electrons. The valence electrons which are present have small ionization energies, and in the solid state they are relatively free to leave one atom and move to its neighbour. These “free electrons” can move under the influence of an electric field and their motion constitutes an electric current. They are therefore responsible for the electrical conductivity of the metal. Copper, aluminium, silver and gold are examples of good conductors used widely in industry.
Nonmetallic elements have low electrical conductivity and act as insulators. They are found to the right of the periodic table with valence shells which are at least half full (except for boron). Their ionization energies are large so that electrons cannot leave an atom easily when an electric field is applied, and they conduct only very small electric currents. Examples of solid elemental insulators are diamond (an allotrope of carbon) and sulfur.
 
Actually, an electron never moves its charge, the charge is intrinsic to the electron. What occurs, to my understanding, is that, in a conducting material, the electrons are not tightly bound to their particular nuclei but exist in cloud, so to speak. When we add electrons to the cloud in one area and remove them from another area, that causes a potential difference and the electrons flow to the relative "vacuum", the relative positive charge (less electrons to balance the protons in the nuclei) side. The same theory that, as Henning shows, motivates water to flow. The same as what makes weather, high and low pressure, high and low potential

It goes to the atom. Protons and Neutrons make up the nucleus with the electrons in an 'orbit' around the nucleus. The electrons are arranged in levels and how many are in each level is dependent on the element. Since the electrons are attracted to the nucleus the inner shell (1st shell) fills up first. The outer most level is called the 'valance shell'. This is the shell that determines conductivity. If there are free electrons in the valance shell then they can move easily from atom to atom. If not then the electrons do not move so well.

Copper and gold have very free electrons in their valence shells. Atoms that make up resistors (porcelain, rubber, wood) do not. At least that's the way I remember it.



Edit to add:
ah shucks, Alphadog already posted what I just wrote and beat me to the 'click'. I knew I was spending too much time verifying facts.

; )
 
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It goes to the atom. Protons and Neutrons make up the nucleus with the electrons in an 'orbit' around the nucleus. The electrons are arranged in levels and how many are in each level is dependent on the element. Since the electrons are attracted to the nucleus the inner shell (1st shell) fills up first. The outer most level is called the 'valance shell'. This is the shell that determines conductivity. If there are free electrons in the valance shell then they can move easily from atom to atom. If not then the electrons do not move so well.

Copper and gold have very free electrons in their valence shells. Atoms that make up resistors (porcelain, rubber, wood) do not. At least that's the way I remember it.



Edit to add:
ah shucks, Alphadog already posted what I just wrote and beat me to the 'click'. I knew I was spending too much time verifying facts.

; )

That is because I copy and paste. Yuk yuk yuk. :D
 
If there was a mass flow (electron flow) in a wire then a gyroscopic effect would have been observed in a coil when a DC current is applied. Just imagine a stack of gyros (coil turns) rotating at close the speed of light. The abscence of the gyroscopic effect rules out the mass flow in a wire.

José
 
If there was a mass flow (electron flow) in a wire then a gyroscopic effect would have been observed in a coil when a DC current is applied. Just imagine a stack of gyros (coil turns) rotating at close the speed of light. The abscence of the gyroscopic effect rules out the mass flow in a wire.

José

I have no idea of how to respond to that :hairraise:

Actually, I do. Allowing your premise that electrons are little gyroscopes, that effect would not happen for the same reason that my flashlight does not bore a hole through solid steel (assuming a bright enough light to contain that much energy).
 
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If there was a mass flow (electron flow) in a wire then a gyroscopic effect would have been observed in a coil when a DC current is applied. Just imagine a stack of gyros (coil turns) rotating at close the speed of light. The abscence of the gyroscopic effect rules out the mass flow in a wire.

José

Gyroscopic effect? I wouldn't carry the analogies too far. To fully understand what is happening, we're talking about electrodynamics, specifically Maxwell's equations which govern how charged particles behave in electromagnetic fields. We won't get into the quantum effects that are also present... Henning's water analogy is an excellent one to understand the basic terms with everyday concepts, but it is just an analogy. Now trying to analyze this "fluid" flow of electons using classical mechanical concepts is not a good idea and was abandoned a couple of centuries ago ;)
 
Gyroscopic effect? I wouldn't carry the analogies too far. To fully understand what is happening, we're talking about electrodynamics, specifically Maxwell's equations which govern how charged particles behave in electromagnetic fields. We won't get into the quantum effects that are also present... Henning's water analogy is an excellent one to understand the basic terms with everyday concepts, but it is just an analogy. Now trying to analyze this "fluid" flow of electons using classical mechanical concepts is not a good idea and was abandoned a couple of centuries ago ;)


Exactly, he asked for simple basic, that's all the water analogy works for.
 
As far as 'mass flow' there isn't.

The electrons moving are more like a tube filled with steel balls side by side and all touching each other. Even if the tube is 100 feet long with hundreds of balls. When you strike a ball on one end of the tube the force is immediately felt on the other end even though there isn't 'mass flow'.

This is another area where the 'water in pipes' analogy breaks down.
 
As far as 'mass flow' there isn't.

The electrons moving are more like a tube filled with steel balls side by side and all touching each other. Even if the tube is 100 feet long with hundreds of balls. When you strike a ball on one end of the tube the force is immediately felt on the other end even though there isn't 'mass flow'.

This is another area where the 'water in pipes' analogy breaks down.

I disagree. I think electrons are constantly moving down the conductor and being replaced by electrons from the other end. Otherwise you would have no flow. And if you use your analogy, if you actually want a flow of steel balls rather than an instantaneous and transient "bop", then there has to be mass flow.
 
The secret to electricity (according to an EE I used to work with) is smoke. If you have a piece of equipment or a wire or anything electrical, and the smoke gets out, it won't work anymore :).
 
As far as 'mass flow' there isn't.

The electrons moving are more like a tube filled with steel balls side by side and all touching each other. Even if the tube is 100 feet long with hundreds of balls. When you strike a ball on one end of the tube the force is immediately felt on the other end even though there isn't 'mass flow'.

This is another area where the 'water in pipes' analogy breaks down.

Kind of but not totally, the force transference with no mass transference still happens in water, that's why pipes knock.
 
The secret to electricity (according to an EE I used to work with) is smoke. If you have a piece of equipment or a wire or anything electrical, and the smoke gets out, it won't work anymore :).

You are right. Have to keep the smoke inside the wires. I just last weekend gave my A&P over $1000 of a $3300 annual bill just to keep that dang smoke inside the wires. :D
 
I disagree. I think electrons are constantly moving down the conductor and being replaced by electrons from the other end. Otherwise you would have no flow. And if you use your analogy, if you actually want a flow of steel balls rather than an instantaneous and transient "bop", then there has to be mass flow.

I don't know. If you use the theory of 'mass xfer' then there would either be a mound or a hole over time at the site of a grounding rod. There isn't and my guess is mass isn't really traveling through the wire.

Also, look at the speed of electricity. If I had to wait for an electron to travel all the way down the wire it'd take longer that it does. If you look at it as the steel balls in the tube you can see why the force is immediate.

I'm not saying its a perfect analogy...
 
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