Alternators Flashcards
What are three examples of dc supplies in a separately excited ac alternator?
- Battery banks
- dc Generators
- Solid state rectifiers
The current used to create the magnetic field is called __________ current.
Excitation
Describe two benefits of a rotating field alternator.
- higher kVa
- easier to cool
List the two types of rotors used in alternators, and describe one benefit of each.
Salient pole
- short in length
- low speed
Cylindrical
- windings imbedded case
- high speed
The amount of voltage generated by each winding in a stator is proportional to the ________ of ______ in the winding.
Number of turns
In a three phase alternator, each phase winding must be physically placed _____ degrees apart.
120
What three factors determine the generated voltage of an alternator.
- Number of armature turns
- Speed of field
- Flux density of field
What is the most common method of controlling the output voltage of an alternator.
Change flux density of field
The main field flux of an alternator can be changed by changing what three values.
- number of turns in the field
- type of core material
- amount of current
What is the most common method of controlling the field flux of an alternator.
Changing the amount of current by adjusting the field rheostat
What two basic sources of field excitation are typically found in A/C alternators.
- separately excited
- self excited
What type of excitation system would be the most reliable and easiest to maintain
Brushless
The purpose of a voltage regulator in an ac alternator is to
Maintain constant terminal voltage to the load
Synchronous reactance in an ac alternator is made up of what two factors
Winding reactance
Armature reaction
Voltage regulation is a percentage between what two values in an alternator?
The change between no load output and full load output voltage