Transformers?

Question

Hi, i'm looking for a clear explanation as to what transformers are. What i know is that they are something to do with coils of wire round a core of a metal, there's some kind of inductance there, and it all has to do with an electro motive force, and what in god's name has the ratio of primary to secondary turns have to do with anything ?
Anyone who can explain these things will get 5 whole points, or whatever the amount of points you get for getting the answer right is.
Thanks.

Answer 1

In simple terms, a transformer is two inductors next to eachother. An inductor is simply a coil of wire. When you pass a current through wire, a magnetic field is created. When you pass it through a coil, it becomes focused through the middle and outside. And when you have a wire in a changing magnetic field, current is 'induced' (or generated) in the wire.

So, when you have current passing through a coil, which is next to another coil with no current source, the magnetic field from the first coil interacts with the second coil, and generates current.

The 'turns ratio' is how many turns are in the first coil compared to the second. This determines how much voltage is generated in the second coil.

If the second coil has less turns than the first, it will have a higher voltage and lower current than the first wire. This is used to distribute power from power plants, as high voltage is easy to maintain across long distances. When this high voltage gets to your house lets say, the coil then induces current in another coil with more turns. This lowers the voltage, but increases the current.

This is useful because houses don't need 10,000 volts, but need more amperage to run appliances.

Answer 2

A transformer is what you get when you have 2 or more inductors situated such that, when you put a current through one of them, the resulting lines of flux generated cross the coils of the other - in other words, they are coupled.

When magnetic lines of flux cross a conductor, a voltage will be induced in the conductor. If the inductors are perfectly magnetically coupled, such as they are close to being when wound on a common core, the voltage induced in the second coil will be proportional to the ratio of turns of the two inductors. For example, if the first coil, which we call the primary, has 100 turns and the second coil (secondary) has 50 turns, and the AC voltage across the primary is 100 volts, then the primary will induce 50 volts across the secondary.

There is an awful lot to the design of transformers, this is just the bare basics.

Answer 3

They're more than meets the eye. Transformers are vehicles that turn into robots and vice-versa. There are good ones called autobots and bad ones called decepticons. Don't you keep up with the movies?

Oh, transformers....

Here's the deal. Current through a wire induces a magnetic field around the wire. If you coil up a wire, you can get a pretty good B-field going in the middle. Now run AC current through it. Changing current means the B-field will change. Now place another coil of current loops around the first (but not connected). Changing magnetic flux through a loop induces a current through the loop. So an EMF is induced in the secondary loop. By varying the ratio of coils between the loops, you can make the secondary have more or less current and less or more voltage (of course current times voltage is conserved). This is very handy, because although you want 120V in your house, it is efficient to use a much higher voltage to transport power around the grid. So you have transformer boxes on your street to step the voltage down.

Answer 4

Transformers work because of the relationships between electric fields and magnetic fields.

The current that's fed into a transformer wraps around a metal core a bunch of times; this creates a magnetic field (just like an electromagnet). The strength of the magnetic field is proportional to the number of turns of wire that go around the metal core.

It turns out that if a magnetic field switches direction (north to south to north) over and over, it creates an electrical field, and if you stick (another) loop of wire in the vicinity of the field, it can make electricity travel through the wire. This is how generators work (like on bicycle headlights).

So, a transformer is kind of like an electromagnet placed next to a generator. The input current powers the electromagnet. The input has to be AC current, which makes the electromagnet switch polarity (north/south) many times per second. The resulting alternating magnetic field induces a voltage in a second coil of wire (the "generator" part), and that produces the output current.

The number of turns of wire in each component is important, because (on the "electromagnet" side) the number of turns affects the strength of the magnetic field; and (on the "generator" side) the number of turns affects the amount of voltage that's induced on the output. It turns out that the ratio of voltage-out to voltage-in, is the same as the ratio of the number of turns in the two coils of wire. Thus, the primary purpose of a transformer is to change voltage.

Answer 5

That's fine that you already know what is coils of wire round a core of a metal, inductance, and electromotive force.

The rest is in any textbook. Or, in short form here:

http://www.industrialbriefing.com/pages/categories/electrical-power-generation/transformer-basics.php

http://en.wikipedia.org/wiki/Transformer

What in god's name has the ratio of primary to secondary turns have to do with anything?

Well, it's quite important. It is the ratio of transformation of voltage.

E.g. if the ratio is 1:2, then the transformed voltage is double or half - depends which side you use as primary.

Answer 6

Robots in disguise!

Sheesh, didn't you ever watch the cartoon?!

As the Irish (or British... I really didn't get her accent) said, it's a DNA-based robot, which means it has a molecular core. As far as them skimming the vehicles to take on their likeness, it's all Sci-Fi. There doesn't have to be a logical, or scientifical, explanation as to why it happens. It's out of this world. It's a completely different technology, science, etc.

Hope this helps.

Answer 7

Transformers are robots energized by a source of energy called the All-Spark. They were split among two races when one race, the Decepticons, were corrupted with the power of the All-Spark. They basically were brought to life by the power of an object called the All-Spark, whose origins remain unknown.