Transformers
What are common efficiencies of
90 to 99 percent at full load
Transformers can change the values of voltage, current and impedance but cannot change what?
Frequency
As a general rule, transformer secondary windings should not be connected how?
In parallel
What is the disadvantage of autotransformers?
There is no line isolation between primary and secondary windings
All values of voltage, current, and impedance in a transformer are proportional to what?
Turns ratio
What is a transformer?
A magnetically operated machine that can change values of voltage, current, and impedance without a change in frequency.
Transformers can be connected as what?
Additive and subtractive polarity
Why do transformers have a very high inrush current when they are first connected to the power line?
Because of the magnetic domains in the core material
Constant-current transformers are also known as what?
Current regulators
What type of transformer helps to filter voltage and current spikes between the primary and secondary sides?
Isolation
What type of transformer has its primary and secondary windings electrically and mechanically separated from each other?
Isolation transformer
Why do inductors provide an air gap in their core material?
It causes the magnetic domains to reset to a neutral position
What is it called when a coil induces voltage into another coil?
Mutual induction
How many windings do autotransformers have?
One
What is added to to schematic diagrams to indicate transformer polarity?
Polarity dots
The primary winding of a transformer is connected to what?
Power line
What is it called when a coil induces voltage into itself?
Self-induction
Constant-current transformers are generally used to provide power to what?
Series-connected loads
A transformer that has a lower secondary voltage than primary voltage is a what?
Step-down transformer
A transformer that has a higher secondary voltage than primary voltage is what?
Step-up transformer
The secondary winding is connected to what?
The load
