GEH-5304A
23
a. Unfasten pigtail.
b. Release spring by pushing in slightly to disen gage locking tab, then pull sprin g back.
c. Remove brush.
2. Brush Installation
The following procedure should be used to install brushes:
a. Place br ush in h older with bevel towards sprin g. Brushes should move freely in h older .
b. Push spring into position until lock tab en gages slot and locks.
c. Con n ect pigtail.
The presence of silicone in DC motors, particularly with totally enclosed con-
structions, will cause rapid brush wear. Sources of silicone include oils, RTV
compounds, hand creams, mold release agents, grease and some insulating
varnishes. These silicone substances must be avoided to ensure proper motor
performance.
Brushes should have their commutator contact surfaces curved to exactly fit the commutator surface.
This is accomplished by “sanding in” the brushes in each brushholder separately. Draw a sheet of
coarse non-metallic sandpaper under the brushes with the rough side toward the brush, while the
brushes are pressed firmly towar d the commutator. Do not use emery cloth. Wh en sa n di n g br us h es,
do n ot get carbon dust into th e win dings. The motor should be thoroughly blown out after sanding the
brushes. Th is can be accomplished by clean ing the dust from the commutator, br ushh olders and adja-
cent parts with a vacuum cleaner, air blast or other suitable means. After the rough sanding, the
brushes should be finely ground to fit using a brush seater. Rotate motor at around nameplate RPM.
Make sure there is no load on the machine (armature current is nil). Carefully and lightly rub the
brush seater across the entire commutator surface for 10 or 15 seconds. Repeat between each and
every set of brush studs. Reverse motor rotation an d repeat. Stop motor an d cut all power to th e mo-
tor an d check brush face. Con tinue seatin g un til br ush face is 85% seated. Again, the motor must be
thoroughly blown out after brush seating, the same as with sanding.
Avoid inhaling carbon and seater dust. GE Industrial Systems recommends
using a dust mask during sanding, seating and blowing or vacuuming.
High voltage and rotating parts can cause serious or fatal injury. The use of all
electric machinery, like all other utilization of concentrated power and rotating
equipment, can be hazardous. Installation, operation and maintenance of elec-
tric machinery should be performed by qualified personnel. Familiarization
with NEMA Safety Standards for Construction and Guide for Selection, Installa-
tion
and Use of Integral HP M oto rs and Generat ors , National Electrical Code and sound local prac-
tices is recommended.