Differences

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--- techtalk:ih:elec02a [2018/12/16 19:41]
hippysmack
+++ techtalk:ih:elec02a [2018/12/16 23:36]
hippysmack
@@ Line 30: / Line 30: @@
 {{  :techtalk:ih:elec:generator_pic_by_sifty.jpg?direct&400|}}
-The brush plate is easily removable, and inspection/ cleanup should be straight forward. ((photo by sifty of the XLFORUM ((http://xlforum.net/forums/showthread.php?t=1592463&page=42)) \\
+The brush plate is easily removable, and inspection/ cleanup should be straight forward. ((photo by sifty of the XLFORUM http://xlforum.net/forums/showthread.php?t=1592463&page=42)) \\
 Care must be taken when installing the brush plate. \\
 Make sure that the brush- armature connecting wire is not pinched (can short circuit to the frame). \\
@@ Line 37: / Line 37: @@
 Ensure the connecting wires are tightened in a position to allow full movement. \\
 And make sure the bare end of the armature brush wire does not contact the case or end cap on assembly.
+====== Terminal insulation ======
+The terminals must be insulated between where they go through the case and connect to the windings. \\
+There will be some sort of fiber or plastic bushing around them at this point. \\
+These can crack or lose their insulating properties through a build up of dust/oil/ grime. \\
+A good cleaning may restore things.
+But you can make new plastic bushes to replace the decades old fibre/plastic ones that are beyond salvage. \\
+The winding insulation test below will indicate the status of this insulation.
+====== Armature ======
+Testing on the Ohms scale between each commutator segment and the exposed iron core will indicate any short circuits to ground. \\
+Each segment should show very high resistance to ground (ideally in the Mega-ohms range). \\
+You can also test between adjacent segments for continuity (this reading should be very low) in the 0.1 ohm sort of range. \\
+Make sure you do not damage the soft copper of the commutator with the pointy test leads when carrying out these tests. \\
+The the armature is where most problems should occur and these tests are very rudimentary. \\
+But rule out obvious issues to begin with.
+====== Simple Generator tests ======
+With the generator cleaned, assembled and on the bench, some simple test with the multimeter in the Ohms scale can tell you a lot about its electrical health. \\
+The figures noted here were the results from 2 generators (different models). \\
+They should be reasonably typical the standard 12V Harley generator. ((photo by sifty of the XLFORUM http://xlforum.net/forums/showthread.php?t=1592463&page=42))
+ \\
+{{  :techtalk:ih:elec:generator_drawing_2_by_sifty.jpg?direct&400|}}
+Field winding resistance: \\
+Placing the leads across the A and F terminals will give you the effective resistance of the field windings (2 windings in series). \\
+The armature circuit is not included as in a healthy generator there is no return path via ground to the meter. \\
+This should be around the 5.8 ohm mark, a higher figure indicates a possible open circuit, and a lower figure may mean a winding is shorting out somewhere.
+Armature resistance: \\
+Placing one lead on a good, clean ground point on the case (shiny metal) and the other on the A terminal, will follow the path through the armature to ground. \\
+This should be very low, typically less than 0.6 ohms but can vary as it depends on the brush/commutator condition.
+Total resistance: \\
+Placing the leads on a good ground point and the F terminal effectively measures the field plus armature circuits in series (from the F terminal, through the field windings, then through the armature to ground). \\
+As a quick check, this result should be very close to the values of the previous tests added together.
+\\
+{{  :techtalk:ih:elec:generator_drawing_3_by_sifty.jpg?direct&400|}}
+With the brushes out there are a couple of further tests available: ((photo by sifty of the XLFORUM http://xlforum.net/forums/showthread.php?t=1592463&page=42)) \\
+Winding insulation: \\
+Placing one lead on a clean ground point of the casing, and the other on either terminal (do both) should give a very high reading (ideally in the Mega-ohms range). \\
+This indicates the windings are not shorting to ground anywhere.
+Winding current: \\
+Connecting the battery through the multimeter in the Amps scale should result in a DC current of around 2 amps. \\
+Ohms law states V = IR, so with 12V and a resistance of around 6 ohms I = V/R which gives the 2 amps (will vary in practice as your winding resistance and battery voltage will differ). \\
+Motor test: \\
+This is probably the best indication, as a generator that will motor with voltage applied indicates all is well with the commutator / brush assembly. \\
+Jumper leads from a good battery were used and a short piece of wire (applied +12V to the A terminal, and -12V to the case and F terminal simultaneously). \\
+The generator was immobilized in a bench vise (between blocks of wood) for this test. \\
+It should rotate quietly and smoothly, with no sparks apart from when you make the connection. \\
+If it motors nicely there should be no reason the unit will not generate when spun. \\
+There are other tests available with the generator on the bike. \\
+(open field voltage, closed field voltage, current tests, all detailed in the manuals) \\
+But if the above tests go OK, \\
+A simple voltage test with the bike running should (hopefully) show around 15V at the A terminal to ground above idle speed, and you are away and riding... \\
 \\

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