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Faults and remedies
Commutation
Type of fault
Causes and remedies
Brush sparking at the leading edge
1 9 10 9
Brush sparking at the trailing edge
1 9
Slight sparking
1 9 1 19 9 9
Violent sparking with showers
9 10 1 1
Arc or flash
1 10
Sparking of some brushes or sets of brushes
9 1 19 0 9 1
Burning of the rear corner of the brushes
1 1 19 9 0
Vibration and breaking of the brush edges
1 1 0
Brushes wear out too fast
9 1 1 1 0 1 9
Uneven brush wear
1 1 0 9 0 1
Plait interruptions and burning
10 11 1 1 1 0 1
Grooves on the brush sides
1
Grooves on the surfaces of contact
1
Metal particles on the surfaces of contact
1 1 0 1
Uneven commutator wear
11 1 1 1 1 0 9
Grooves on the commutator surface
1 1 1 1 1 1 0 0
Symmetrical stains on the commutator
1 10 1 1
Asymmetrical stains on the commutator
0
Scored commutator surface
1 1 1 1 19 0 9
Possible cause
Remedy
1) The brushes are out of neutral zone
Reset neutral position
) Asymmetry between the brush holder studs
Correct the distance between the studs
) Commutating pole flux too high
Increase commutating pole air gap
) Commutating pole flux too low
Decrease commutating pole air gap
) Excessive no load operation
Use suitable brushes, reduce the number of brushes
) Dirt and oil on the commutator
Clean the commutator and identify cause
) Abrasive dust on the brush surfaces
Remove the brushes and brush them clean
) Overload
Reduce the load
9) Vibrations
Check the alignment, rebalance if necessary
10) The armature winding is damaged
Repair, rewind if necessary
11) Inadequate ventilation
Trace the causes, then consult ABB if necessary
1) Current density at the brushes is too low
Reduce the number of brushes
1) Current surges
Choose suitable brush types
1) The air is too damp
Let in fresh air, select suitable brushes
1) The air is too dry
Let in fresh air, select suitable brushes
1) Dust or sand suspended in the air
Fit filters and eliminate the causes
1) Gases or acids in the air (*)
Let in fresh air, select suitable brushes
1) Excessive brush friction
Reduce brush pressure, make use of non-abrasive brushes
19) Brushes not adapted to the commutator
Adapt the brushes perfectly, as previously shown
0) Different brush types
Use brushes of the same type
1) The commutator is stained when the
machine is not in operation
Raise the brushes
) Brush pressure is too weak
Replace the brush spring and brush presser pad
) Excessive brush pressure
Replace the brush spring and brush presser pad
) Uneven brush pressure in different brushes
Adjust pressure, replace the faulty brush springs if necessary
) The brush holders are not perpendicular
Restore the correct distance between brush holder cases
and commutator ( ÷ . mm)
) The brushes are jammed in the brush holders
Clean the brush holders
) Too much play in the brush holder
Change brush holder
) Vibrations on the brush holder studs
Reinforce the studs with insulating rings
9) The brush holders are not parallel
Adjust brush holders
0) The brush holder case is too distant from the
commutator
Adjust distance to about ÷ . mm
1) Uneven current distribution to the brushes
Increase current density; adjust pressure, make use of more
abrasive brushes
) Mica insulator protruding from the commutator
Smooth the mica insulator and the edges of the segments
) Burrs on the commutator segments
Remove the burrs, smooth the edges, replace brushes with a
more suitable grade
) Ovalized commutator
Turn the commutator
) Broken soldering
Solder the commutator lugs
) Scored commutator
Turn the commutator
) Protruding commutator segments
Rub the commutator with a pumice stone, turn the
commutator if necessary
) No choke coil where needed
Connect the choke coil
9) Choke coil reactance different from specified one Replace the choke coil
(*) Harmful gases which may be present in the air: sulphates, silicones, chlorine, ammonia. consult ABB in these cases