TRAFO

TRAFO

Transformer or transformers or transformer is an electromagnetic component that can change the level of an AC voltage level to another.

Transformer works on the principle of electromagnetic induction. Alternating input voltage that lies the primary cause magnetic flux that ideally all concatenated with the secondary winding. This flux induces alternating EMF in the secondary winding. If efficiency is perfect, all the power in the primary winding will be transferred to the secondary winding

Primary-Secondary relationship

Flux in the transformer
The formula for the magnetic flux generated primary winding is and the formula for the EMF induced in the secondary winding is happening.
Because the two coils are connected with the same flux, then where to rearrange the equation will be obtained such that. In other words, the relationship between the primary voltage to the secondary voltage is determined by the ratio of the primary winding to the secondary winding.

Losses in the transformer
in The above calculation is valid only if the primary-secondary clutch is perfect and there is no loss, but practice occur several disadvantages, namely:

1. The loss of copper. Losses in the copper windings caused by the copper resistance and         electrical current flowing.
2. Losses clutch. Losses incurred due to the primary-secondary coupling is not perfect, so not all primary induced magnetic flux cutting the secondary winding. These losses can be reduced by rolling multi-layered winding between primary and secondary.
3. Losses wild capacity. Losses caused by stray capacity contained in the coil-winding transformer. This loss greatly affects the efficiency of the transformer for high frequency. These losses can be reduced by rolling the primary and secondary windings are semi-random (bank winding)
4. Loss hysteresis. Losses that occur when the AC primary current reverses direction. Due to transformer core can not change the direction of the magnetic flux immediately. These losses can be reduced by using low reflectance core material.
5. Losses skin effect. As another conductor alternating current flowing, the current tends to flow on the surface of the conductor. This increases the capacity loss and also increase the relative resistance of the coil. These losses can be decreased by using Litz wire, that wire consisting of several small wires that are isolated. For radio frequency used geronggong wire or a thin sheet of copper instead of regular wire.
6. Losses eddy current (current megrim). Losses caused by EMF input that causes the current in the magnetic core of the fight changes that generates magnetic flux GGL. Because of the magnetic flux change, occurs eddy magnetic flux in the core material. This loss is reduced when used core layers.

Efisiensi

Transformer efficiency can be determined by the formula Due to the losses in the transformer. Then the efficiency of the transformer can not reach 100%. For low-frequency power transformer, the efficiency can reach 98%.

Types of transformers

Step-Up
Step-up transformer is a transformer that has a secondary winding more than the primary coil, thus serving as a stress riser. These transformers are commonly encountered in power plants as a riser generated voltage into a high voltage generator used in long distance transmission.

Step-Down
Step-down transformer having a secondary winding less than the primary coil, thus serving as the lowering of the voltage. This type of transformer is very easy to find, especially in the AC-DC adapter.

Autotransformator

This type transformer consists of one continuous coil electrically, with the middle leads. In this transformer, most of the primary winding is also a secondary winding. Phase current in the secondary winding is always opposite to the primary current, so that the same power rate secondary windings can be made by wire thinner than a regular transformer. The advantage of autotransformator is small physical size and lower loss than other types of two loops. But this type of transformer can not provide electrical isolation between the primary winding to the secondary winding.
Moreover, autotransformator can not be used as a stress riser more than a couple of times (usually no more than 1.5 times).

Autotransformator variabel

Autotransformator variable is actually ordinary autotransformator middle intercepts can be changed, allowing for comparison of primary-secondary windings are changing

Transformator isolasi

Isolation transformer having a secondary winding which amounts to the same as the primary coil, so that the secondary voltage is equal to the primary voltage. But in some designs, the secondary winding is made a little more to compensate for the loss. This can serve as a transformer isolation between the two loops. For audio application, this type transformer has many digantikaan by coupling capacitors.

Pulse transformer

Pulse transformer is a transformer that is designed specifically to provide the output pulse waveform. This type of transformer core material are rapidly saturated so that after the primary current reaches a certain point, the magnetic flux stops changing. Since the EMF induced in the secondary winding is formed only if there is a change of magnetic flux, only provide output current transformer core is not saturated, ie when the current in the primary winding reverses.

Transformator fase three

Three-phase transformer is actually a three transformers connected specifically to each other. The primary winding is usually connected in star (Y) and secondary windings are connected in delta ().