Theory Flashcards
In a transformer, with no load connected. There is some small current required to magnetize the core. This is called
Excitation current
Ideally the material used in a transformer should have a property of ______________ retentivity
Low
Ideally the material used in the core of a transformer should have property of ___________ permeability
High
Ideally the material used in the core of a transformer should have property of ____________ resistance
High
Transformer in which the secondary is more than the primary voltage is called a
Step up transformer
Transformer that converts a high 7200V from the utility down to 120/240 is called a
Distribution transformer
The magnetically operated device that can change values of voltage current and impedance without changing frequency is a
Transformer
Any transformer flux that does not follow the core and escapes into the air is called
Flux leakage
A transformer in which the secondary voltage is less than the primary voltage is a
Step down transformer
An industrial transformer that normally has small VA 240v or 480v primary and a 120v secondary is called
A control transformer
A transformer that doesn’t isolate the input from the output is called
A auto transformer
Two to design characteristics that are used in the construction to reduce core losses
Layered core
Soft steel
The efficiency of practical transformers is a range of
96-99%
Difference between transforming AC and DC
DC cannot be transformed
The primary of a transformer is a ________ and the secondary is a ___________
Load
Source
What can transformers do
Change voltage
Change currents
Change impedance
What is mutual induction
When changing current in one coil induces an EMF in the other
Primary is side with _______ energy
Input
Secondary is the side with ________ energy
Output
Currents that circulate in the core are called
Eddy currents
