trade engineering · lamels on the commutator surface • burnt edge, mainly the trailing edge •...

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Commutator Problems

TRADEENGINEERING

solution for success

1

Good performance

Appearance• uniform, medium brown film

The film formation depends on• Brush grade• Surface state• Temperature• Electrical load• Humidity• Ambient conditions

copyright 27.04.2020

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


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-


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-


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-


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-


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-


8

Ambient conditionsPaper Industry


9

Ambient conditions

Commutator from paper industrywith grade -EG571-.


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-

10copyright 27.04.2020

11

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


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


13

Brush Vibration

vibration sign


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


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


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


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-


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


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


Trade Engineering Ltd7, Ochrid str., 6400 Dimitrovgrad - Bulgariatel: +359 896 496 305; +359 884 323 [email protected]

TRADEENGINEERING

solution for success

trade engineering · lamels on the commutator surface • burnt edge, mainly the trailing edge •...

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