trade engineering · lamels on the commutator surface • burnt edge, mainly the trailing edge •...
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Commutator Problems
TRADEENGINEERING
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1
Good performance
Appearance• uniform, medium brown film
The film formation depends on• Brush grade• Surface state• Temperature• Electrical load• Humidity• Ambient conditions
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2
Good performance
Appearance• Good brush surface• Good commutator surface• Full contact point in the brush surface• Brush material -SA45-• Application copper tube industry• Oil evaporation in the production enviroment
perfect contact surface
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3
Low load conditions
Appearance• Groove formation• Disappearance of the film protaction• Commutator threading
Problem• Low load conditions• Low commutator temperature
Remedial action• Reduction of number of brushes• Change of air direction• Throttling of cooling air• Low load resistant brush grade e.g. -IM9101-, -IM31-
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4
Low commutator temperature
Appearance• No good film formation
Problem• 20°C commutator temperature
Remedial action• Increase of temperature by- throttling of cooling air- change of air direction- reduction of number of brushes• Use grades with high resistance e.g. -IM9101-, -IM31-
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5
High humidity
Appearance• Smearing of the film• Damage of the film• Groove formation• Brush wear
Problem• High humidity
Remedial action• Increase of brush pressure• Sandwich design – e.g. -EG236S-• Self cleaning brush grades e.g. -EG571-, -N19X-
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6
Low load ambientconditions
Appearance• Palbable grooves in the contact surface• Groove formation
Problem• Low load conditions• ambient conditions (dust)
Remedial actions• check load conditions• Improvement of filtering• Use material with high resistivity e.g. -IM9101-, -IM31-
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7
Ambient conditionsDirty air
Appearance• Oxidation in the non-applied area of the commutator• Groove formation• Commutator wear out
Problem• Ambient conditions (H2S, SO2. HCL..)
Remedial action• clean air• Sandwich design – e.g. -EG236S-• Self cleaning brush grades e.g. -EG571-, -N19X -, -IM8876-
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Ambient conditionsPaper Industry
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Ambient conditions
Commutator from paper industrywith grade -EG571-.
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Ambient conditionsOil influance
Appearance• Automobile industry• Patchy film• High brush wear
Problem• Ambient conditions (oil)
Remedial action• Clean air• Improve filtering system• Sandwich design – e.g. -EG236S-• Brush grades e.g. -EG571-, -N19X-, -IM8876-
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Brush holder distancetoo high
Appearance• Brush vibration• Brush sparking• Markings of brush chattering• Broken brush at the edges
Problem• Brush holder distance too high
Remedial action• Adjust holder distance to 2,5mm
brush holder distance too high
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12
Brush Vibration Appearance• Broken brushes at the contact and brush face surface• Damage on the flexible cable• Flexible cable out of the hole• Shiny brush side surface• Loose tamped contacts
Problem• Flexible cable out of the hole due to the high vibration frequency• Brush sparking• Vibrations by means ofa) out-of-roundnessb) external vibrationsb) too smooth collector surface
Remedial action• Check out-of-roundness• Check for external vibrations( bearing belt pulley, basement etc)• Improve possibly the brush design• Brush design with split top• Increase of brush pressure• Possible overhaul commutator
broken in the brush surface
damage in the flexible wire
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13
Brush Vibration
vibration sign
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14
Carbon Brush sparking
Appearance
Problem
Remedial action
• Extreme brush sparking
• Overload• Wrongly set neutral zone• Wrong brush grade• Poor brush pressure• Debris into the brush pocket
• Check the load conditions• Check the neutral zone• Choice the right brush grade• Improve the brush design• Check the brush pressure• Clean the brush pocket
brush sparking
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15
Stand still current
Appearance
Problem
Remedial action
• Burn marks in brush size
• Stand still current• High starting current• Result: out-of-roundness• Brush vibration
• Remove the brushes when the motor stay out of function for a lot of period• Remove burn marks immediately from the commutator surface
stand still current
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16
Commutation problems Appearance
Problem
Remedial action
• Spot burn marks every two or three lamels on the commutator surface• Burnt edge, mainly the trailing edge
• Commutation problems by means of- wrongly set neutral zone- wrong/defective inter poles- winding damage- not suitable brush grade- wrong brush design- no good brush current sharing
• Check neutral zone• Sandwich design e.g. -EG236S- will help for better commutating• Better commutating brush grades e.g. -EG283- ,-EG236- • Check the stator and rotor winding• Improve the brush design • Choice brush grade with high current sharing capabilities
winding problem bad commutation
commutation problem
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17
Discolored flexible cable Appearance
Problem
Remedial action
• Cables of brush body are discolored
• Commutation problems by means of- wrongly set neutral zone- brush overload- wrong/defective inter poles- winding damage- brush stuck into the pocket- poor brush pressure- brush sparking
• Check neutral zone• Check motors parameters• Check stator and rotor winding• Check carbon brush to move free into the brush pocket• Check the brush pressure• Sandwich design e.g. -EG236S-• better commutating brush grade e.g. -EG283-, -SA45-, -SA35-
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18
Copper drag Appearance
Problem
Remedial action
• Copper drag
• Uneven current distribution armature windings• Unequal number of windings in adjacent slots • Inconsistency in armature windings related to number of coils, slots and commutator bar• Low commutator temperature• Vibrations with high frequency and low amplitude
• More suitable brush grade• Increase of surface temperature• Check the commutator out of round• Check the armature windings which related with numbers of coils, slots and commutator bars
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19
Flash over
Appearance
Problem
Remedial action
• Damaged brush holders• Damaged commutator
• Flash over by means of- voltage peak- dirt environment- vibration- carbon dust in the motor compartment
• Regular cleaning• Check out-of-roundness• Remove the carbon dust from motor compartment
copyright 27.04.2020
Trade Engineering Ltd7, Ochrid str., 6400 Dimitrovgrad - Bulgariatel: +359 896 496 305; +359 884 323 351info@tradengineering.comwww.tradengineering.com
TRADEENGINEERING
solution for success
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