Custom Search
|
|
|
||
 ELECTRICAL
Motors and Generators-Continued
n Collector Rings, Commutators, Brushes:
excessive sparking
surface dirt
grease (check cleanliness with clean canvas paddle)
sparking or excessive brush movement caused by eccentricity,
sprung shaft, worn bearings, high bars or mica
surface scratches
roughness
end-play resulting from magnetic-center hunting of rotor
inadequate brush freedom
nonuniform brush wear
poor commutation
improper brushes
incorrect brush pressure. Brush spring pressure should be between
1-3/4 to 2-1/2 psi of brush-commutator contact area for light
metallized carbon or graphite brushes; for pressure for other type
brushes, check manufacturer's data. (Measure with spring scale.)
n Starters, Motor Controllers, Rheostats, Associated Switches:
damaged or defective insulation
loose laminations
defective heater or resistance elements
worn contacts
shorts between contacts
arcing
grounds
loose connections
burned or corroded contacts. Worn contacts and defective heater
resistance elements should be replaced
7-33
|
 
|
|
|
||
