GEH-5304A
12

Before starting the motor, remove al l unused shaft keys and loose rotating parts

to prevent t hem fro m f lying off.

A. Inspection Before St ar ti ng
These inspection procedures should be followed before starting the machine for the first time, after an ex-
tended shutdown or after a teardown for extensive maintenance or repair.
1. Bearings and Couplings
Machines with ball or r oller bearings are greased at the factor y and will need n o attention until r elu-
brication is necessary as suggested in t he Maintenance section of thi s i ns truc tion book .
If the flexible couplings are a lubricated type, they should be checked to see that they contain the
proper amount of lubricant.
Make sur e that all grease plugs are tight.
2. Com mutator and B r ushes
Brushes should be worn in to have at l east 85% contact over th e br ush sur face and con tin uous con tact
from heel to toe. The commutator surface and undercut mica should be clean and free from dirt,
grease, paint spots or brush dust.
Brushes should be free to move in the holders and all springs should be down and latched. Brush
pigtail connections should be tight and th e pigtails should not interfer e with th e action of th e spring or
brush and should be clear of any other part of the machine.
B. Rectified Power Suppl ies
When DC motors are operated from rectified power supplies, the pulsating voltage and current wave forms
affect th e motor performan ce by increasing motor heating and degradin g commutation. Because of these ef-
fects, it is necessary that the motors be designed or specially selected to suit this type of operation .
The ratings of DC motors intended for operation from rectified power supplies are based upon motor tests
using a suitable power supply. The specific ch aracteristics for thr ee-phase rectified power supplies descri bed
in the Power Supply Identification section are in common use. For operation of motors from rectified
power supplies other than those given in th is section, refer to GE In dustrial Systems.
A motor may, under some con ditions, be oper ated from a power supply different from th at indicated on the
nameplate. Letter s used to identify power supplies in common use have been chosen in alph abetical order of
increasing magn itude of ripple curr ent. Power supply compatibility can be judged by Table 4.