Commutator Check Chart - GE GEH-5304A Instructions Manual

LIGHT TAN FILM over entire commu-
tator surface is one of many normal
conditions often seen on a well-
functioning machine-
STREAKING on the commutator surface signals the
beginning of serious metal transfer to the carbon
brush. Check the chart below for possible causes.
COPPER DRAG, an abnormal build-up of commutator
material, forms most often at trailing edge of bar.
Con-dition is rare, but can cause flashover if not
checked.
Frequent visual inspection of commutator surfaces can warn you when any of the above conditions are developing so that you can take early corrective action. The chart below may indi-
cate some possible causes of these conditions, suggesting the proper productive maintenance.
Electrical
Adjustment
Streaking
Threading
Grooving
Copper Drag
Pitch Bar-Marking
Slot Bar-Making X
The purpose of the Commutator Check Chart is to help you spot undesirable commutator conditions as they develop so you can take corrective action before the condition becomes serious.
This chart will also serve as an aid in recognizing satisfactory surfaces.
The box chart above indicates the importance of selecting the correct brush and having the right operating conditions for optimum brush life and commutator wear.
For additional information or help with carbon brush application or commutation problems. Contact your nearest GE Sales Office or Distributor.

Commutator Check Chart

For Comparing Commutator Surface Markings
SATISFACTORY COMMUTATOR SURFACES
MOTTLED SURFACE with random film
pattern is probably the most frequently
observed condition of commutators in
industry.
WATCH FOR THESE DANGER
THREADING of commutator with fine lines results
when excessive metal transfer occurs.
leads to resurfacing of commutator and rapid brush
wear.
PITCH BAR-MARKING produces low or burned spots
on the commutator surface.
markings equals half or all the number of poles on the
motor.
CAUSES OF POOR COMMUTATOR CONDITION
Light
Electrical Electrical Armature
Overload Load Connection
X
X
X
X
HOW TO GET THE MOST VALUE FROM THIS CHART
SLOT BAR-MARKING, a slightly dark-
er film appears on bars in a definite
pattern related to number of conductors
per slot.
GROOVING is a mechanical condition caused by
It usually abrasive material in the brush or atmosphere. If
grooves form, start corrective action.
HEAVY SLOT BAR-MARKING can involve etching
The number of these of trailing edge of commutator bar. Pattern is re-
lated to number of conductors per slot.
Unbalanced Brush
Shunt Pressure
Field (Light) Vibration
X
X
X X
X X X
33
GEH-5304A
HEAVY FILM can appear over entire
area of efficient and normal commu-
tator and, if uniform, is quite accept-
able.
Type of Brush
In Use Contamination
Abrasive Porous Abrasive
Brush Brush Gas Dust
X X X X
X X
X X
X X
X
X