Autotransformers Flashcards

1
Q

What is the main principles of operation in an autotransformer?

A

Electromagnetic induction;

Mutual and Self.

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2
Q

What are the two autotransformer windings called?

A

Common winding;

Series winding.

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3
Q

Does the transformer ratio of volts/ turn still apply to autotransformers?

A

Yes, the V/T of the common and series windings will be identical.

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4
Q

When comparing mutual induction transformers and autotransformers of similar coils, which has a higher capacity?

A

The autotransformer.

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5
Q

What is transformed apparent power?

A

The VA that is transformed through mutual induction in the common winding.

SX = VCom • ICom.

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6
Q

What is conducted apparent power?

A

The VA that is conducted, through the series winding.

SC = VCom • ISer.

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7
Q

The total apparent power of an autotransformer is ____________.

A

The sum the of conducted and transformed apparent power.

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8
Q

What is an autotransformer best suited for?

A

Small Voltage changes (Variac);

When smaller, cheaper, better Voltage regulation and higher capacity (over mutual induction transformers) is desired;

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9
Q

What are the major flaws of autotransformers?

A

They do not isolate the secondary from ground;

Higher available fault current;

Equipment may see source voltage in a step down common winding failure.

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