GE GEH-5304A manual Commutator Check Chart

GEH-5304A

Commutator Check Chart

For Comparing Commutator Surface Markings

SATISFACTORY COMMUTATOR SURFACES

LIGHT TAN FILM over entire commu-	MOTTLED SURFACE with random film	SLOT BAR-MARKING, a slightly dark-	HEAVY FILM can appear over entire
tator surface is one of many normal	pattern is probably the most frequently	er film appears on bars in a definite	area of efficient and normal commu-
conditions often seen on a well-	observed condition of commutators in	pattern related to number of conductors	tator and, if uniform, is quite accept-
functioning machine-	industry.	per slot.	able.

WATCH FOR THESE DANGER

STREAKING on the commutator surface signals the	THREADING of commutator with fine lines results	GROOVING is a mechanical condition caused by
beginning of serious metal transfer to the carbon	when excessive metal transfer occurs. It usually	abrasive material in the brush or atmosphere. If
brush. Check the chart below for possible causes.	leads to resurfacing of commutator and rapid brush	grooves form, start corrective action.
	wear.

COPPER DRAG, an abnormal build-up of commutator	PITCH BAR-MARKINGproduces low or burned spots	HEAVY SLOT BAR-MARKING can involve etching
material, forms most often at trailing edge of bar.	on the commutator surface. The number of these	of trailing edge of commutator bar. Pattern is re-
Con-dition is rare, but can cause flashover if not	markings equals half or all the number of poles on the	lated to number of conductors per slot.
checked.	motor.

CAUSES OF POOR COMMUTATOR CONDITION

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.

Streaking

Threading

Grooving

Copper Drag

Pitch Bar-Marking

Slot Bar-Making

Electrical Adjustment

X

Electrical Overload

X

Light

Electrical

Load

X

X

Armature Connection

X

Unbalanced

Shunt

Field

X

Brush

Pressure

(Light)

X

X

X

X

Vibration

X

X

Type of Brush

In Use

Abrasive	Porous
Brush	Brush
X	X
	X
X
X
X

Contamination

	Abrasive
Gas	Dust

XX

X

X

X

X

HOW TO GET THE MOST VALUE FROM THIS CHART

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.

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