ADVANTAGES AND DISADVANTAGES OF THE AUTOTRANSFORMER CONNECTION

AUTOTRANSFORMERS CONNECTION ADVANTAGES AND DISADVANTAGES
What Are The Advantages And Disadvantages Of Autotransformer Connection?


Summarizing the advantages of the autotransformer connection:

 • There are considerable savings in size and weight.

• There are decreased losses for a given KVA capacity.


• Using an autotransformer connection provides an opportunity for achieving lower series impedances and better regulation.

Summarizing the disadvantages of the autotransformer connection:

• The autotransformer connection is not available with certain threephase connections.

• Higher (and possibly more damaging) short-circuit currents can result from a lower series impedance.

• Short circuits can impress voltages significantly higher than operating voltages across the windings of an autotransformer.

• For the same voltage surge at the line terminals, the impressed and induced voltages are greater for an autotransformer than for a two winding transformer.

In many instances, the advantages of the autotransformer connection outweigh its disadvantages.

For example, when very large MVA capability is required and where a Grd.Y-Grd.Y connection is suitable, an autotransformer is usually the design of choice.

Because an autotransformer cannot provide a Δ-Y connection, autotransformers are not suitable for use as generator step-up transformers.