UNION 2D0058 - Caterpillar

Personal injury or death can result from improper troubleshooting and repair procedures.The following troubleshooting and repair procedures should only be performed by qualified personnel familiar with this equipment.
Refer to Safety Section, "Generator Isolating for Maintenance" for information regarding the procedure to safely isolate the generator.A visual inspection should be initially directed at the areas that are most prone to damage and deterioration. The most prone areas to damage and deterioration are listed below:
Ground Insulation. Ground insulation is insulation that is intended to isolate components that are carrying current from components that are not carrying current.
Support Insulation. Support insulation is usually made from one of the following items: a compressed lamination of fibrous materials, polyester, or felt pads that have been impregnated with various types of bonding agents.There are many different types of damage that can occur in these areas. Several of the different types of damage are listed below:Thermal Aging - Thermal aging can cause the degradation of insulation or the deterioration of insulation. An examination of the coils may reveal that the insulation has expanded into the ventilation ducts. This is the result of a loss of bond which will cause the insulation material to separate. The insulation material could also separate from the conductors on the windings.Abrasion - The surfaces of coils and the surfaces of connectors may be damaged by abrasion. These surfaces may also be damaged by contamination from other sources. An example of these sources would be chemicals or abrasive substances.Cracking - Cracking of insulation may result from mechanical stress. The structure that is used to brace the stator winding will become loose if the problem is not corrected. Further mechanical damage or electrical damage may also result.Erosion - Erosion can be caused when foreign substances rub against the surfaces of coil insulation.