What Is Auto-Transformer, Comparison Between Two Winding Transformer And Auto-Transformer, Advantages Of Auto-Transformer

Hello Guys, welcome back to my blog. In this article, I will discuss what is auto-transformer, comparison between two winding transformer and auto-transformer and the advantages of an auto-transformer.

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What Is Auto-Transformer?

What Is Auto-Transformer, Comparison Between Two Winding Transformer And Auto-Transformer, Advantages Of Auto-Transformer
Auto-Transformer


An auto-transformer as only one winding which is common for both primary and secondary. In auto-transformer, only one winding is used as primary as well as secondary.

Comparison Between Two Winding Transformer And Auto-Transformer

The basic comparisons are:

01. Windings
02. Copper Requirement
03. Primary & Secondary Winding Connection
04. Power Transfer
05. Size & Cost
06. VA Rating
07. Efficiency
08. Resistance & Leakage Reactance
09. Voltage Regulation
10. Voltage Variation

Now I will discuss in detail about these all points.


01. Windings - In two winding transformers, two separate windings are used one for primary and another for secondary whereas in the case of auto-transformer, the only single winding is used which is common for both primary as well as the secondary winding.

02. Copper Requirement - In the case of two winding transformers, copper requirement is more whereas, in the case of auto-transformer, the copper requirement is less.

03. Primary & Secondary Winding Connection - In two winding transformers, the two windings primary and secondary are electrically isolated whereas, in the case of auto-transformer, primary and secondary are electrically connected.

04. Power Transfer - The power transfer is fully inductively whereas in the case of auto-transformer power transfer is by both inductively as well as conductively.

05. Size & Cost - The size and cost of two winding transformers are more whereas, in the case of auto-transformer, the size and cost are less.

06. VA Rating - In the case of two winding transformers, VA rating is less whereas, in the case of auto-transformer, VA rating is high.

07. Efficiency - The efficiency of two winding transformers is less whereas the efficiency of the auto-transformer is high.

08. Resistance & Leakage Reactance - In the case of two winding transformers, resistance and leakage reactance are high whereas, in the case of auto-transformer, resistance and leakage reactance are low. 

09. Voltage Regulation - In the case of two winding transformers, voltage regulation is high whereas, in the case of auto-transformer, voltage regulation is low.

10. Voltage Variation - In the case of two winding transformers, smooth and continuous voltage variation is not possible whereas, in the case of an autotransformer, smooth and continuous voltage variation is possible.

Advantages Of Auto-Transformer

01. We all know that copper requirement is less this is one of the advantages.
02. The efficiency is more
03. The cost is less.
04. The size is less.
05. The copper losses are less.

So, guys, these are some advantages of auto-transformer.

Limitation Of Auto-Transformer 

01. If the section of winding common to primary and secondary is removed then the full voltage will appear across the secondary winding, which is more dangerous.

I hope this article may help you all a lot.

Thank You For Reading.

Tags: What Is Auto-Transformer, Comparison Between Two Winding Transformer And Auto-Transformer, Advantages Of Auto-Transformer
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