When you take a MODERN current generator OF ANY KIND apart, you will find two things right away,
(I say 'modern' because I know some nimrod is going to pull a static generator out of his butt at any time!)
'FIELD' WINDINGS.
These are NOT the 'Outside' windings,
Field Windings are the 'Collectors' or 'Stator' part of the generator.
They will be on the spinning armature on a DIRECT CURRENT (DC) generator,
They will be inside the larger part of the case outside the rotor in a modern ALTERNATING CURRENT GENERATOR (Alternator for short).
Since there aren't very many DC generators out there anymore, I'm going to stick with the 'Alternator' or 'Alternating Current Generator'...
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Part 1. ROTOR.
The rotor in a modern alternator is an 'Electro-Magnet, and a fairly powerful one.
The rotor has TWO contacts called 'Slip Rings', continuous, smooth metal bands that receive external current,
A fairly large winding of wire to form the 'Electro-Magnet' when current is applied,
A SOFT IRON core to focus & direct the magnetic field to 'Pole Pieces',
And 'Pedals' or 'Leaves' to create an ALTERNATING 'North' & 'South' poles when it's spun.
An actual Rotor showing Bearing Surface, Slip Rings, Pole Faces, front frame or front half of housing, and drive nose.
MANY OF YOU WILL BE LOST RIGHT HERE...
THE 'FIELD' ON ANY GENERATOR OR MOTOR IS THE 'MAGNETIC FIELD',
WHICH MAY BE THE ROTOR OR THE OUTSIDE WINDINGS DEPENDING ON TYPE OF GENERATOR.
MOST PEOPLE BELIEVE 'FIELD' IS ALWAYS THE OUTER WINDINGS, AND THAT IS INCORRECT.
'FIELD' REFERS TO THE MAGNETIC FIELD GENERATING PART OF THE UNIT.
IN the case of modern alternators, that is the ROTOR,
The rotor is the magnetic Field Producing Part Of the unit,
And the outside windings that most people refer to as 'Field Windings' are the STATOR WINDINGS.
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Part 2, STATOR,
The 'STATOR' is the outside windings in the case of modern 'Alternators'.
These stator windings are there for the MAGNETIC FIELD to pass through, and INDUCE a current in them.
That current is collected up by the way the windings are TERMINATED (End Terminals for each winding) and there are a few different designs...
Since the Magnetic Poles switch from North To South very quickly,
You will be getting AC, or 'Alternating Current'.
AC switches polarity very quickly from Positive to Negative as the North & South poles pass by each winding in the coil.
Since this happens the STATOR DELIVERS ALTERNATING CURRENT (Hence the name 'Alternating Generator').
Most people don't know if you tap directly into the Stator of the common car alternator, you can WELD OFF IT!
IT's capable of 220 volt, 3 phase power in it's raw form!
You can run 110 volt AC appliances directly off it when wired correctly!
We'll get to some of that later...
The 'Stator' is a series of windings off set to each other,
So one magnetic pole leaf can induce them right after another, then the polarity of the moving magnetic field changes very quickly, and the windings produce again as the polarity changes.
A VERY efficient way to produce electrical current for the home hobbies, vehicle engine, ect....
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Part 3, RECTIFIER.
Refection from AC to DC can be done two ways,
One is the old fashioned 'Armature' with a bunch of commutator leaves with brushes contacting individual windings.
This collects all the 'Positive' pulses on one brush, all the Negative pulses on the other brush.
This was VERY inefficient.
Copper contact leaves came out of the insulating material at high speed, there was limited space on the rotor for windings so it didn't produce very much usable current.
Most 'DC' generators that rectify at the current at the armature/commutator will fly apart if you spin them very hard, and with limited collector windings, they were low output.
We'll stick with 'Alternating Current Generators' (Alternators) since they are MUCH stronger, much more efficient, take much less maintenance, and generally do a better job all the way around.
With modern Alternators, there is a 'Solid State' (no moving parts) component that makes this possible. The DIODE.
http://en.wikipedia.org/wiki/Diode
A Diode is a 'One Way' gate valve for electrical current,
Depending on how it's installed in the circuit, it will only let current pass in one direction...
By using a pair, the 'Positive' pulse of the AC is let out, then it's let back in through another diode once it does it's job.
In the average alternator, there are 6 diodes for the three sets of stator windings, one 'Positive', one 'Negative' for each winding.
(Some heavier alternators will use more than one set for each winding, so you will see them in multiples of 6 in that event)
A RECTIFIER will be a fairly large piece of usually aluminum, sometimes copper, with 'Fins' on it to cool the diodes as they work.
There will be THREE terminals for the three sets of field windings, and there will be SIX diodes set in that aluminum
AC current goes in through the field winding terminals, DC current comes OUT the rectifier common terminals.
Couldn't be more simple!




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