Saturday, February 18, 2012

How do transformers increase voltage?

How to transformers increase voltage while keeping the same current(i may be wrong about that)



How do you convert ac current to dc current?How do transformers increase voltage?Not resistance, magnetism. If you put current through a wire, you get a magnetic field aroudn the wire. If you coil the wire, you get a strong magnetic field around the coil. If you put another coil next to that first coil, the magnetism from the first coil induces a current into the second coil. For reasons I cannot explain smoothly, it is the building or decaying of the magnetic field that best induces a current in the second coil. Thus, you use alternating current so that the magnetic field is building or decaying. If you put direct current through the first coil, you will get a constant magnetic field that will not induce a current in the second coil.



The sizes of the coils and number of wraps can be considered analagous to the gear size and number of teeth.



Look up a rectifier bridge for how to turn AC into DC.How do transformers increase voltage?
"How to transformers increase voltage while keeping the same current..."



They don't keep the same current. The current is reduced or increased by the same factor that the voltage is increased or reduced. If I take an AC power source rated at 10 volts and step it up to 100 volts with a transformer, I will draw 10 amps from the 10 volt source for every 1 amp I draw from the 100 V secondary, assuming I have a 100% efficient transformer. Power in (10v * 10 amps) equals power out (100v * 1 amp).



The change in voltage happens by electromagnetic induction. A transformer is 2 coils of wire: A primary coil which is connected to a power source and a secondary coil which is connected to the load. The factor by which the voltage is stepped up or down is equal to

(# turns on secondary coil)/(# turns on primary coil).How do transformers increase voltage?Gintable's analogy of electrical gears is a very good one. The thing about gears and transformers is that the amount of POWER you get out can never be greater than the amount of power you put in. The power delivered to a load by an electric circuit is the product of the voltage across the load and the current through the load. The product, volts聽x聽amps in the secondary of a transformer can never be higher than the volts x amps in the primary. If the voltage goes up, then the current must go down by a proportional amount.



As for how it actually works, check out this article:



http://en.wikipedia.org/wiki/TransformerHow do transformers increase voltage?
essentially has a certain voltage per turn.

so if the secondary has more turns then the secondary voltage will be higher.

eg if primary voltage is 100Vac and you have 100 turns, than the transformer will have 1Vac per turn.

If you have a secondary winding of 1000 turns, then the secondary voltage will be 1 * 1000 = 1000Vac

(Note this is theory only as magnetic saturation will have an effect!!!!! 1 turn on a mains supply will not result in a transformer but a dangerous firework :D )



As to the current, you are incorrect. A perfect transformer the energy is the same on both sides. thus a higher secondary voltage would mean a proportionally lower secondary current.How do transformers increase voltage?"How to transformers increase voltage while keeping the same current(i may be wrong about that)"



You are incorrect about that: transformers are analogous to "electrical gears", which trade voltage for current and vice-versa.



How do you convert ac current to dc current?

Transformer

Rectifier

Smoothing capacitor

Limiter zener diode

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