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techtalk:ih:elec02a [2018/12/16 23:36]
hippysmack
techtalk:ih:elec02a [2018/12/16 23:47] (current)
hippysmack
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 {{  :​techtalk:​ih:​elec:​generator_drawing_2_by_sifty.jpg?​direct&​400|}} {{  :​techtalk:​ih:​elec:​generator_drawing_2_by_sifty.jpg?​direct&​400|}}
-Field winding resistance: \\+**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). \\  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. \\  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. 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: \\+**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. \\  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. This should be very low, typically less than 0.6 ohms but can vary as it depends on the brush/​commutator condition.
  
-Total resistance: \\+**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). \\ 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. As a quick check, this result should be very close to the values of the previous tests added together.
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 {{  :​techtalk:​ih:​elec:​generator_drawing_3_by_sifty.jpg?​direct&​400|}} {{  :​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)) \\ 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: \\+**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). \\ 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. This indicates the windings are not shorting to ground anywhere.
  
-Winding current: \\+**Winding current**: \\
 Connecting the battery through the multimeter in the Amps scale should result in a DC current of around 2 amps. \\  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). \\ 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: \\+**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. \\ 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). \\ 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). \\