GE GEH-5304A - Manual (Page 12)

GEH-5304A
12
Before starting the motor, remove all unused shaft keys and loose rotating parts
to prevent them from flying off.
A. Inspection Before Starting
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 roller bearings are greased at the factory and will need no attention until relu-
brication is necessary as suggested in the Maintenance section of this instruction book.
If the flexible couplings are a lubricated type, they should be checked to see that they contain the
proper amount of lubricant.
Make sure that all grease plugs are tight.
2. Commutator and Brushes
Brushes should be worn in to have at least 85% contact over the brush surface and continuous contact
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 the pigtails should not interfere with the action of the spring or
brush and should be clear of any other part of the machine.
B. Rectified Power Supplies
When DC motors are operated from rectified power supplies, the pulsating voltage and current wave forms
affect the motor performance by increasing motor heating and degrading 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 characteristics for three-phase rectified power supplies described
in the Power Supply Identification section are in common use. For operation of motors from rectified
power supplies other than those given in this section, refer to GE Industrial Systems.
A motor may, under some conditions, be operated from a power supply different from that indicated on the
nameplate. Letters used to identify power supplies in common use have been chosen in alphabetical order of
increasing magnitude of ripple current. Power supply compatibility can be judged by Table 4.