GE GE752 manual Brushes, Commutator, Creepage Band, Flash Ring

GEK±91584D, Vertical Drilling Motor, Type GE752

Brushes	brush±shunt terminal connections and all brush-
	holder cable connections are tight.

Brush wear is determined by measuring actual brush length from the top of the carbon. Lift the brush spring, remove the brush and measure brush length on the longest side.

NOTE: If brush replacement is not required, be sure that brushes are of sufficient length to last until the next inspection.

If one or more brushes are worn to or near the mini- mum length listed in the DATA section it is generally rec- ommended that all twelve brushes be replaced at the same time.

WARNING: To avoid possible electrical shock or injury from rotating equipment, do not remove or replace brushes while equipment is energized or rotating.

If brushes are to be replaced, see the BASIC RE- PAIRS, Brush Replacement section for brush installa- tion instructions.

If brushes are not to be replaced, the following brush inspection should be made:

CAUTION: When replacing brushes, use only the GE recommended grade. Mixing of brush grades in the same motor or changing brushes to anoth- er grade may seriously affect commutation, sur- face film, commutator and brush life. See the DATA section for brush grade.

1.Inspect all brushes to be sure they are not chipped or broken. Make sure brush shunts are not frayed or broken. Replace any brush which shows damage of any kind.

NOTE: Chipped, burned or rough±faced brushes may indicate the commutator needs resurfacing.

2.Move the brushes up and down in their carbon- ways to be sure brushes slide freely.

3.Check brush shunts to be sure they are not twisted or out of position, Fig. 6. Make sure all

Commutator

Inspect the commutator for possible flashover dam- age. The commutator should be clean, smooth, glossy and free of high mica, high bars, flat spots or rough sur- faces.

If there are indications that the commutator is out± of±round (as evidenced by variations in width of the ridge between brush paths), check the concentricity of the commutator with a dial indicator. Condemning limits for concentricity are listed in the DATA section.

If the commutator requires grinding, refer to Com- mutator Resurfacing in the BASIC REPAIRS section of this manual for instructions.

Creepage Band

Clean the creepage band (located on the commuta- tor cap) with a clean cloth dipped in an approved sol- vent. Inspect the band for possible flashover damage.

Make sure the creepage band is tight on the commu- tator cap.

Flash Ring

Examine the flash ring for possible flashover dam- age. Wipe the flash ring clean. Keep ring free of dirt and varnish.

BRUSH	KEEP SHUNTS CLEAR
SHUNTS	OF LEVER ARMS

FIG. 6. CORRECT POSITION OF BRUSH

SHUNTS. E±22568.

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