Autotransformers Flashcards
What are the main principles of operation in an autotransformer?
Electromagnetic induction;
Mutual and Self.
What are the two autotransformer windings called?
Common winding;
Series winding.
Does the transformer ratio of volts/ turn still apply to autotransformers?
Yes, the V/T of the common and series windings will be identical.
When comparing mutual induction transformers and autotransformers of similar coils, which has a higher capacity?
The autotransformer.
What is transformed apparent power?
The VA that is transformed through mutual induction in the common winding.
SX = VCom • ICom.
What is conducted apparent power?
The VA that is conducted, through the series winding.
SC = VCom • ISer.
The total apparent power of an autotransformer is ____________.
The sum the of conducted and transformed apparent power.
What is an autotransformer best suited for?
Small Voltage changes (Variac);
When smaller, cheaper, better Voltage regulation and higher capacity (over mutual induction transformers) is desired;
What are the major flaws of autotransformers?
They do not isolate the secondary from ground;
Higher available fault current;
Equipment may see source voltage in a step down common winding failure.
