Case studies - DC motors

Transcription

1 Technical Information Case studies - DC motors Page: 1

2 Good performance uniform, medium brown film Film formation depends on Brush grade Surface state Temperature Electrical load Humidity Ambient conditions Page: 2

3 Good performance Page: 3

4 Low load conditions Groove formation Disappearance of the film Commutator threading low load conditions low commutator temperature Reduction of number of brushes Change of air direction Throttling of cooling air low load resistant brush grade e.g. F63, E55 Page: 4

5 Low load Page: 5

6 Low commutator temperature no film formation 20 C commutator temperature Increase of temperature by - throttling of cooling air - change of air direction - reduction of number of brushes F brush grades Page: 6

7 High humidity Smearing of the film Damage of the film Groove formation high humidity Increase of brush pressure Sandwich design e.g. E101M self cleaning brush grades e.g. E108, F49 Page: 7

8 Low load Ambient conditions Palbable grooves in the contact surface Groove formation Low load and/or ambient conditions (dust) s see low load conditions Improvement of filtering Page: 8

9 Ambient conditions Dirty air Oxidation in the non-applied area of the commutator Groove formation Commutator wear out Ambient conditions (H2S, SO 2. HCL..) clean air Sandwich design e.g. E101M self cleaning brush grades e.g. E108, F49 Page: 9

10 Ambient conditions Papierfabrik Page: 10

11 Ambient conditions Commutator paper industry with E498 (self cleaning bush grade) Page: 11

12 Ambient conditions Oil influence Automobile industry patchy film high brush wear ambient conditions (oil) clean air Sandwich design e.g. E101M self cleaning brush grades e.g. E108, F49 Page: 12

13 Holder distance too large Brush vibration Brush sparking Markings of brush chattering Brush holder distance too large Adjust holder distance to 2mm Page: 13

14 Holder distance too large Page: 14

15 Brush vibration crater formation in the contact surface Contact interruption by means of vibration Brush sparking Check out-of-roundness Check for external vibrations( bearing belt pulley, basement etc) improve possibly the brush design Page: 15

16 Brush vibration Shiny brush side surface defective shunts loose tamped contacts Vibrations by means of a) out-of-roundness b) External vibrations b) Too smooth collector surface Check out-of-roundness, possibly skimming Roughening brush design with split top Increase of brush pressure Page: 16

17 Brush vibration Page: 17

18 Brush vibration patchy, un-uniform film slight burn marks out-of-roundness Check of out-of-roundness Change of brush design Page: 18

19 High bar damage of brush edges high bar Check out-of-roundness Turning Overhaul Page: 19

20 Brush sparking extreme brush sparking Overload wrongly set neutral zone Check load conditions Adjust neutral zone better commutating brush grade and / or alternative brush design Page: 20

21 Stand still current Burn marks in brush size stand still current high starting current Result: out-of-roundness Brush vibration Avoid stand still current Remove burn marks immediately Page: 21

22 Stand still current Page: 22

23 Commutation problems Spotting, burn marks partly uniformly Commutation problems by means of - wrongly set neutral zone - wrong staggering - wrong/defective inter poles - winding damage Check neutral zone Sandwich design e.g. E101M better commutating brush grade Page: 23

24 Commutation problems Burnt edge, mainly the trailing edge Commutation problems by means of - wrongly set neutral zone - wrong staggering - wrong/defective inter poles - winding damage Check neutral zone Sandwich design e.g. E101M better commutating brush grade Page: 24

25 Commutation problems Page: 25

26 Discolouration of cables Cables of one brush wafer are discoloured Commutation problems by means of - wrongly set neutral zone - wrong staggering - wrong/defective inter poles - winding damage Check neutral zone Sandwich design e.g. E101M better commutating brush grade Page: 26

27 s by kind of winding or winding damage Spotting, burn marks, partly on more bars Commutation problems Brush sparking progressive bar marking sandwich design e.g. E101M better commutating brush grade possibly self-cleaning brush grades Page: 27

28 Copper drag Copper drag Low commutator temperature vibrations with high frequency and low amplitude more suitable brush grade increase of surface temperature Page: 28

29 Wrong fitting burnt contact surface of one brush wafer Pressure finger of brush holder pushes one-sidedly overloading Maintenance Page: 29

30 Flash over Damaged brush holders Damaged commutator Flash over by means of - voltage peak - dirt - vibration Regular cleaning check out-of-roundness Page: 30