1993/12/27 Caterpillar

All SR4 Generators

Reference: Service Magazine; July 12, 1993; page 10; "Preventive Maintenance to Reduce Risk of Stator Failure".

Reference: Special Instruction, SEHS9124, "Cleaning and Drying of Electric Set Generators".

Periodically generators should be inspected for cleanliness. Contaminants such as dirt, dust, grease, salt, or oil films should not be allowed to accumulate on the windings. When inspecting generators that are out of service, visually check for foreign material, accumulation of dirt, grease, or moisture on windings. Also check for movement of wires, tie wraps and wedges. Insulation should be checked by using a megger insulation tester.

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When servicing or repairing electric power generation equipment. * Make sure the unit is off-line (disconnected from utility and/or other generators power service) and either locked out or tagged DO NOT OPERATE. Remove all fuses. * Make sure the generator engine is stopped. * Make sure all batteries are disconnected. * Make sure all capacitors are discharged. * Make sure residual voltage in the rotor, stator and the generator is discharged. * Failure to do so could result in personal injury or death.

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Because of the volatile nature of many cleaning solvents, extreme caution must be exercised when using them. If unsure about a particular cleaning fluid, refer to the manufacturer's instructions and directions. Always wear protective clothing and eye protection when working with solvents.

Cleaning of generators can be classified into four categories.

Normal cleaning for dry dust and dirt

Cleaning procedures associated with this cleaning classification are wiping with a dry lint free rag, vacuuming, and use of low pressure dry air.

Light cleaning for grease and oil

Cleaning procedures associated with this classification are wiping using cleaners. Guidelines for using cleaners are:

1. Cleaners should not contain chlorinated solvent and should be of a non-phosphate type.

2. Cleaner should not be allowed to stay on parts for an undue length of time.

3. Rinse generator well with salt free fresh water.

4. Dry the generator thoroughly before placing it back into service.

5. After several cleanings stator should be re-varnished.

Heavy cleaning or extreme cleaning

Cleaning procedures associated with this classification are high pressure power wash 10300 kPa (1500 psi) and steam cleaning 100 to 210 kPa (15 to 30 psi) @ 107 to 133° C (250 to 300° F).

Guidelines for heavy or extreme cleaning are:

1. Rinse generator well with salt free fresh water.

2. Dry the generator thoroughly before placing it back into service.

3. Windings must be re-varnished.

4. Reseal with red sealer.

Cleaning of leads, electrical and electronic components.

Cleaning procedures for this classification is:

1. Wiping using cleaners. Follow the normal cleaning for dry dust and dirt procedure, or the light cleaning for grease and oil procedure. Do not use chlorinated or petroleum based solvents. These solvents will cause the leads to swell. Also, do not spray water stream on parts.

The cleaning schedule should be based upon application and location. Generally generators should be cleaned when the following conditions exist:

* Generators should be cleaned yearly.

* During generator overhaul.

* Whenever megger results are unacceptable.

* Applications in extreme dirt, salty, humid environments may require more frequent cleaning, i.e. (rock dust, marine aux., out door installations, etc.) May require weekly cleaning.