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The Advantages And Disadvantages Of Autotransformer Are Analyzed
- Oct 09, 2017 -

The auto-transformer has the following advantages:

1) low consumption materials and low cost.

Because transformer silicon steel sheet and the quantity of copper wire is used and winding induction voltage and rated current, rated that related to the capacity of the winding, autotransformer winding capacity is reduced, the less material consumption, low cost.

2) low cost and high efficiency.

Due to the decrease of copper wire and silicon steel, the copper loss and iron loss of the autotransformer are lower than the double winding transformer in the same current density and magnetic flux density, so the benefits are higher.

3) convenient transportation and installation.

Because it is lighter than the double winding transformer with capacity, small size and small footprint.

4) improve the limit manufacturing capacity of the transformer.

The limit of transformer manufacturing capacity generally limited by transportation, in the same transport limitations, in the same transport conditions, autotransformer capacity than double winding transformer manufacturing.

The use of autotransformer in power system can also have adverse effects.

The disadvantages are as follows:

1) increase the short circuit current of the power system.

Due to the high, medium voltage winding autotransformer electrical connection between the two, its only with the capacity of ordinary double winding transformer short-circuit impedance (1 k / 1) times square, so after using autotransformer in power system, makes the three phase short circuit current increased significantly.

Since the neutral point of the autotransformer has to be directly grounded, the single-phase short circuit current of the system is greatly increased, and sometimes more than three phase short circuit current.

2) some difficulties in regulating pressure.

Is primarily due to its high, medium voltage winding electric contact caused by the autotransformer may have a way of regulating three, the first is installed within self coupling transformer winding with load change separately position regulating device;

The second is to install additional transformers on high voltage and medium voltage lines.

These three methods are not only difficult to make, but also have shortcomings in operation (such as the voltage affecting the third winding).

3) complicate the overvoltage protection of windings.

Due to the high, medium voltage winding autoformer contact, as either side in a amplitude corresponding to the winding insulation level of lightning surge, on the other side of overvoltage shock wave amplitude may be beyond the insulation level.

In order to avoid the occurrence of this phenomenon, a series of valve lightning arresters must be installed on both sides of high and middle pressure.

4) make relay protection complicated.

Although there are some disadvantages in each autotransformer, but countries still attaches great importance to the application of autotransformer, mainly with the development of the power system to large capacity of high voltage is inseparable, as capacity increases, the voltage rise, the advantages of the autotransformer is more outstanding.