Transformers?

what is the mean of transformers ?


my question is about the inductor !


this is my college engineering assignment question hope some body can help me ....


thank you|||(m)





What does a transformer do? Transformers form a way control voltage. They take voltage and either step voltage down, step voltage up or isolate voltage in one area from another. So why is it so important to control this voltage. Take for example your local power company. It uses a step up transformer to give high voltage to the power lines which creates low amperage. Then before entering your home or local business steps the voltage back down so the voltage entering is not excessive.





What parts make up a transformer? A transformer is made up of a three main components; the laminated iron core, primary and secondary windings. The primary winding is connected the power entering the transformer (input voltage). The secondary winding is connected where the power is going to (output voltage). The laminated core is used to separated the primary and secondary windings from have any physical connection.





So how do transformers work? There are no moving parts of a transformer, instead a transformer uses induction to pass electricity from the primary winding to the secondary winding. Easy way to understand what induction is it uses a electromagnetic force to take the voltage from the primary winding and move it to the secondary winding. We control induction with turn ratio.





What is a turn ratio? A turn ratio is the relationship between the primary and the secondary winding. If there was 120v entering the transformer and 24 volts leaving the transformer. Our voltage would be stepping down with a 5/1 turn ratio. Simple math is used to calculate this; voltage entering / voltage leaving the transformer. With 120 / 24 you would have 5/1 ration.





How do you size a transformer? You size a transformer for secondary winding of a transformer. The secondary winding is rated in VA (volts times amperage). An example of this would be you have a 24v control circuit thats capacity is 2amps. You would take your voltage (24v) and multiply it by your maximum amperage (2amps) which would be 24 times 2, which equals 48 or 48 va. This means you would need a transformer rated for 48va.





Do transformers need to be serviced? No, with no moving parts there is no maintenance required. Once a transformer has gone bad, which will general show on the primary windings, it will need to be replaced. Some transformers come with a fuseable link, or a safety. If a transformer has been tripped or has gone bad, it is a general rule to search for a source causing the problem. A bad transformer is never "the problem" only a symptom of the real problem.





What are the different types of transformers? There are many types of transformers you will see in the field; step up, step down, isolating, multi tap and autotransformers. There are also another type which is a three phase transformer, this transformer pertains more to voltage entering a commercial building. As a general rule the most common type of transformer you will see is a step down transformer (control voltage).





What is the difference in these types of transformers? Step up transformers take the primary winding and step the voltage up for the secondary winding. Step down transformers take the primary winding and step is down for the voltage on the secondary winding. Isolating transformers have the same voltage on the primary and secondary. A multi tap transformer is a step up or down transformer that has multi taps on either the primary winding or secondary winding. An autotransformer is a special types of transformer which does not follow common rules of transformers. It uses a continuous winding that is tapped to provide a step down or step up function.





Transformers play a key role in AC powered systems. They are a way to control voltage. There is no maintenance required to transformer though they are excellent indicators of problems. Understand these terms and principles is key to troubleshooting and designing electrical circuits.





An inductor is a passive electronic component that stores energy in the form of a magnetic field. In its simplest form, an inductor consists of a wire loop or coil. The inductance is directly proportional to the number of turns in the coil. Inductance also depends on the radius of the coil and on the type of material around which the coil is wound.





For a given coil radius and number of turns, air cores result in the least inductance. Materials such as wood, glass, and plastic - known as dielectric materials - are essentially the same as air for the purposes of inductor winding. Ferromagnetic substances such as iron, laminated iron, and powdered iron increase the inductance obtainable with a coil having a given number of turns. In some cases, this increase is on the order of thousands of times. The shape of the core is also significant. Toroidal (donut-shaped) cores provide more inductance, for a given core material and number of turns, than solenoidal (rod-shaped) cores.





The standard unit of inductance is the henry, abbreviated H. This is a large unit. More common units are the microhenry, abbreviated 碌H (1 碌H =10-6H) and the millihenry, abbreviated mH (1 mH =10-3 H). Occasionally, the nanohenry (nH) is used (1 nH = 10-9 H).





It is difficult to fabricate inductors onto integrated circuit (IC) chips. Fortunately, resistors can be substituted for inductors in most microcircuit applications. In some cases, inductance can be simulated by simple electronic circuits using transistors, resistors, and capacitors fabricated onto IC chips.





Inductors are used with capacitors in various wireless communications applications. An inductor connected in series or parallel with a capacitor can provide discrimination against unwanted signals. Large inductors are used in the power supplies of electronic equipment of all types, including computers and their peripherals. In these systems, the inductors help to smooth out the rectified utility AC, providing pure, battery-like DC.|||transformers and inductors are two different critters. This is about all the help I can give.





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


http://en.wikipedia.org/wiki/Inductor|||Well, a transformer is used to convert high voltage and low current on one side to low voltage and high current on the other, and vice-versa|||Transformer is an electrical device, used to transform electrical energy from one circuit to another, by means of electromagnetic inductance. Furthermore, it is a kind of inductor with two or more windings. Through the mutual inductance, current in one winding called a primary will induce current into the other windings called secondaries.|||Transformers are devices used to either step-up or step-down the voltage.They have primary and secondary windings.





These two windings(inductors ),they determine whether it's a step-up or step-down transformer.when the number of turns in the primary is less when compared to the secondary then it is called step-down transformer n vice-versa for step-up.





To be precise, when the number of turns increases the magnetic lines of force cut by the coil increases(This is accroding to faraday's law of electromagnetic induction),hence the output from the coil is directly proportional to the number of windings.





To have more insight into these transformers:refer electrical engineering books by B.L Theraja.





All the best..