GE GEH-5304A - page 25

GEH-5304A

G. Mechanical

Check the condition of air filters and replace filters if they are dirty. Check for unusual noises which were

not present when th e unit was originally installed. Check all electrical conn ections for tightn ess. Clean out

any dirt from screens, louvers, etc. which would interfer e with th e flow of cooling air.

H. Shaft E nd P lay

The CD2512AT-CD2813AT designs use a wavy wash er (preload spring) to eliminate en dplay.

I. Waterproof Machines

Water proof mach in es require the use of sealing devices to exclude water from the bearings and fr om entering

openings in the magnet frame. When a waterproof machine has been disassembled, it will be necessary to

remove the old sealing compound from around the mating surfaces of the bearing brackets and magnet

frame, from underneath the field pole bolt heads and bearing cap to bearing bracket bolt heads, and from

around the conduit box adapter threads to the magnet frame. Reapply new sealant (use Titeseal T20-66,

light weight, GE Part No. 905A999AC009) to th ese areas and wipe excess sealant with a clean r ag slightly

dampened with mineral spirits. Do not use silicone sealants. When accessories such as brakes and ta-

chometers are disassembled, it will be necessary to reseal at the accessory mounting face. Pr ior to reassem-

bly, inspect for damage at the gaskets around enclosure covers and at the shaft rubbing seals located in the

bea ring caps.

J. Lubri c ati on of Flexibl e Couplings

Flexible couplings are normally lubricated with a semi-fluid grease or an oil. The coupling manufacturers’

instructions should be followed in choosing a lubricant and setting relubrication intervals. GE ball bearing

grease D6A2C5 is a suitable lubricant for flexible couplin gs in most application s.

Flexible couplings which join a small machine to a large machine may have two different size coupling

halves joined by an adapter plate. Couplings of this type have a separate lubricant supply for each half.

Therefore, both h alves must be lubricated separately.

K. Insulation

Eliminate sources of contamination and moisture for maximum insulation life.

Contamination includes excessive moisture, oily vapors, conducting and non-conducting dust, chips and

chemical fumes. Contamination is best avoided by proper enclosure and ventilation. Filters, ventilation

from a remote clean air source, unit coolers and a totally enclosed construction are all possible means of

protecting DC machines in adverse environments. Space heaters protect against moisture damage by main-

tainin g the mach ine above de w-p oi n t du r i ng st or a g e or wh en i dl e . Sp a ce h ea t ers s h ou ld be a r r a n g ed so t h a t

they are automatically energized whenever power is removed from the motor. Space heaters do not supply

enough heat for drying out windings which have been water-soaked.

Mechanical factors include shock, vibration, overspeed, etc. Maintaining machines in good mechanical re-

pair, including isolation from excessive external shock and maintenance of smooth running conditions, will

contr ibute to long in sulation life.

The insulation system in these machines is capable of withstanding some short time periods of operation at

temperatures h igher than than used for th e basis of machine rating. Prolonged or excessively h igh tempera-

ture will cause the insulation to become brittle and crack, leading to premature failure. Application data is

available from GE Industrial Systems for any particular machine giving suggested maximum loads for vari-

ous operating conditions. Operation within these maximum loads will limit the temperature to suitable val-