Loose Metal and Solder

break and necessitate disassembly of the machinery to

Electrical Connections

remove broken glass and mercury.

Inspect all electrical connections (particularly

Any unusual noise in operating machinery may

terminals and terminal board connections) at frequent

also indicate bearing malfunction. When a strange

intervals to ensure they are tight. Loose connections

noise is heard in the vicinity of operating machinery,

result in increased contact resistance and increased

make a thorough inspection to determine its cause.

heating, which may result in breakdown. Use

Excessive vibration will occur in operating machinery

locknuts, lock washers, or other means to lock

with faulty bearings, and inspections should be made

connections that tend to become loose because of

at frequent intervals to detect the problem as soon as

vibration. Inspect soldered terminal lugs for looseness

possible.

or loss of solder, and tighten solderless terminal lugs

occasionally. When electrical connections are opened,

Loose Metal and Solder

clean all oil and dirt from contact surfaces before

reconnecting. If the contact surfaces are uncoated

Keep all small pieces of iron, bolts, and tools away

copper, sandpaper and clean immediately before

from the machines. Where it is necessary to do any

joining. If the contact surfaces are silver-plated, do not

soldering, make sure that no drops of solder get into

use sandpaper. Use silver polish or a cloth moistened

the windings and that there is no excess of solder on

slightly with an approved cleaning agent. Coat the

soldered joints, which may later break off due to

finished joint with insulation varnish. Steel bolts for

vibration and fall into the windings.

making electrical connections should be zinc plated.

Make sure that exposed electrical connections are

Bolts and Mechanical Fastenings

adequately insulated to protect against water and

moisture and injury to personnel. This applies

Care should be exercised not to disturb the

commutator clamping bolts on dc machines. Inter-

especially to exposed connections at terminal straps

ference with these may make it necessary to turn or

extending outside the frames of propulsion motors

grind the commutator to restore it to service. Other

and generators, Motor connection box leads should

bolts and mechanical fastenings on both the stationary

b e assembled as shown in figure 1B10 of

and rotating members should be tightened securely

DOD-STD-2003-1 (Navy).

when the machine is erected, checked after the

equipment has run for a short time, and thereafter

Filter Cleaning and Equipment Inspection

checked at regular intervals to make sure that they are

tight. Particular attention should be given to the bolts

Clean or replace permanent-type air filters

used to clamp any insulation.

quarterly. Machine temperatures should not be

allowed to rise above the design rating, and filters

Rotor Hardware

should be changed as often as necessary to prevent the

entrance of oil, water, metal shavings, abrasives from

If an inspection of a rotor shows that there is a

grinding, and dirt. Upon completion of overhaul and

looseness of keys, bolts, or other fastenings, check for

prior to operation without filters, ensure that all dirt,

evidence of damage due to this looseness. Such

abrasives, chips, and so forth, are removed from

looseness may result in worn dovetail keys, damaged

pockets in the foundations in the vicinity of the

windings, or broken dovetails on the end plates. Two

foundations of electrical rotating machinery. After a

or three drivings usually will ensure the tightness of

machine has been cleaned, inspect the windings for

the keys, but nevertheless they should be checked

visual evidence of mechanical damage to the

regularly.

insulation or damage caused by excessive action of

any solvents used in cleaning.

Armature Banding

Information on the repair and revarnishing of

damaged insulation can be found in NSTM, chapter

Check the banding wire on dc armatures at regular

intervals to make sure that it is tight.

300.

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