SUPPORT GP-RADIATOR 3351415 - Caterpillar

Introduction
Generator winding component failures can be traced back to various causes, including harsh environment, application abuse, installation deficiencies, and factory quality defects.Effective generator maintenance practices and protective relaying are a necessity to preventing insulation weakening, mitigating extent of damage, minimizing downtime, and determining root cause of generator component damage caused by an electrical fault.Effective Generator Winding Maintenance Practices
Following these simple requirements will help to insure the greatest life of generator windings.
Check and record winding insulation strength at the time of commissioning, periodically thereafter, and monitor trends.
Use space heaters when the generator is not in operation.
Monitor operating stator temperature and trend.
Clean generator windings periodically.Note: Refer to the above mentioned Special Instruction media for more details on proper stator maintenance practices.Effective Protective Relaying Practices
Consideration of the following in generator protective relaying will help as a guide to provide a safe environment for generator windings.
Basic factory protective relay settings are required to be adjusted at commissioning to meet application requirements, to ensure the most effective level of protection. Complex applications require a coordination study. It is important that a coordination study provides settings to protect the generator as well as the load.
Due to the greater presence of destructive energy on the bus being fed by the generator, many applications, including paralleling applications, require a higher level of protective relaying than the basic factory protective relay functions provided in standard generator set controls.
Avoidance of protective relaying nuisance tripping requires careful consideration by experts in the industry to implement settings while still providing effective generator protection.
The protective functions of greatest interest for utility companies are over-voltage, under-voltage, over-frequency, and under-frequency.
The priority reason for these functions is to protect the utility from generator disturbances.
Generator rotor and excitation components integrity benefit from protective functions reverse var and phase sequence.
Other devices such as voltage regulators and varistors on the rectifier assembly are also effective at mitigating rotor and excitation component failures.
Generator stator integrity benefit from protective functions ground fault, 100% Stator Ground Protection by Injection, phase differential, phase unbalance, and synchronizing check relay.
Other devices such as surge protection and stator temperature RTDs are also effective at mitigating stator winding failures, and recording history.
Surge protection is an absolute necessity in generator voltage applications above 1kV where events, such as utility bus incidents or inadvertent breaker tripping upstream, could cause reflective surges of damaging energy to the stator coils.
Implementation of a complex utility grade protective relay will provide a more accurate, faster acting protection than a basic non-utility grade relay. Utility grade relays are differentiated in that a utility grade relay can be programmed with the generator capability curve, and will operate based on area under the curve as opposed to discrete number set points. In addition to providing a superior level fast acting protection, utility grade protective relays can be programmed more concisely, which promotes less possibility of nuisance tripping.Note: Refer to Caterpillar Publication, Application and Installation Guide, LEBW7543, "Generator Paralleling Switchgear", for additional details on protective relaying.Many of these risk evading devices, including various protective relaying