OPERATIONAL TESTING OF THE GENERATOR

TM 9- 2920- 224- 34&P

OPERATIONAL TESTING OF THE GENERATOR

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THIS WORK PACKAGE COVERS:

Testing

INITIAL SETUP:

Tools and Special Tools

Tools and Special Tools - Continued

General mechanic's tool kit (item 1, WP 0017 00)

Relay, reverse current

Test stand, 500A

Regulator, voltage

Test set, generator

Test bench setup consisting of:

Recorder, temperature

Suitable mount or holder for generator

Materials/Parts

28 V dc power source, regulated output

Sealant (item 13, WP 0016 00)

SPST switch, 300 A minimum

Goggles (item 7, WP 0016 00)

Battery, storage, 24V

Rubber gloves (item 8, WP 0016 00)

Fixed resistor, 1.25 ohms 300 A

Equipment Conditions

Fixed resistor, 0.1 ohm 400 A

Generator assembled except for band assembly and

RPM indicator

gasket

Testing

1. Brush Run--In Procedure.

a. Securely mount generator on test bench or stand and connect to brush run--in setup.

CAUTION

Ensure rheostat is never set to infinite resistance.

Generator would reach excessive speed.

b. Set rheostat at minimum resistance.

Close switch; generator shall run as a motor with armature turning counterclockwise when viewed from drive end.

CAUTION

Unusual noise or vibration while generator brushes are

being run in is an indication generator is not in

serviceable condition. Operational testing should be

halted until generator can be disassembled and repaired

d. Increase resistance setting of rheostat until armature is rotating at about 4000 rpm.

e. Allow generator to run at about 4000 rpm for three hours to polish brush seats, then open switch to stop

generator.

Remove any brush from generator and inspect commutator contact surface of brush; polished area shall meet

minimum percentage of brush end surface of 85%.

g. If brush seat polished area does not meet minimum requirements, install brush and repeat steps e and f

except run time shall be one and one--half hours.

h. When brush seat polished area meets minimum requirements, install brush.

Remove, inspect, and install each of the other five brushes, one at a time. Repeat steps g and h, as

applicable, until all brushes are properly polished.

WARNING

Compressed air used for cleaning purposes will not

exceed 30 psi. Use only with effective chip guarding and

personal protective equipment (goggles/shield, gloves,

etc.).

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