I just found in interesting video on how to use infrared camera….

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Generator rotor, as moving part of power generation system, have a big influence in your plant availability. Generator rotor is designed with excellent combination of electrical, mechanical and material science that make it rugged, strong and have capability to hold electrical and mechanical force for a long time and also withstand high temperature operating system. Generator rotor consist of  field coils that are well insulated, supported and ventilated in a compount structure which are rotating at very high speed (usually 1500 – 3000 rpm). As a rotating part, it is common that it become deteoriate and get performance reduction. The degradation of the generator rotor can be caused by several factors, but most of them is caused by electrical and mechanical factor such as breakdown in insulation due to high temperature and mechanical wear because the rotor design usually limited by temperature, electrical insulation and mechanical force

because of that, some generator rotor failure conditions can be occur during its operation which are :

Shorted Turns and Field Grounds

Generator rotor shorted turns can occurs when the insulation in the rotor winding is damaged. a local shorted turns can be occurs anywhere in the rotor winding, and it possibly not affect the overall operations of generator, depends on the level of winding damage. The common locations of the shorted turns are in the endwinding area under retaining ring.
Field grounds occur because of a breakdown in the groundwall insulation. the locations can be under the retaining ring section, slot portion of the winding, at the main lead and terminals or collector and collector terminals, or at the bore copper region.
What is the impact of the field ground to generator operations?
we know that the source of excitation for electromagnetic field is ungrounded. A single ground will not cause current to circulate in the field forging, but if second ground occur, a current will circulate in the forging and in a short time you can get seriously damage on the forging.

Thermal sensitivity problem

Thermal sensitivity related to excessive vibration of the generator rotor, induced by the heating effect of the field current. when the coil forces act unevenly, or whn a temperature differential exists across the rotor, the rotor tend to bow, causing subsequent vibration and imbalance operation.

Contamination

Contamination can occur during generator operation or during overhaul activities. from design engineering point of view, the contaminations is affected by generator cooling design. A hydrogen cooled generator is well sealed and should be have very little contamination (except during overhaul activities, some contaminant such as oil or dust can be occured if you are not carefully maintain housekeeping of your overhaul area).
A TEWAC (Totally Enclosed Water and Air Cooled) generator unit will have a little contaminant from its make up air system. An OV (Open Ventilated) Generator is the most unit that get large amount of contamination.

Collector, Bore Copper and Connection Problems

This mainly happen to generator unit which use brush to collect the field current (brush generator). due to the components is a vital link in the excitation path, they should be get more attention from maintenance people. If “Collector Flashover” occur, it can create creepage path and can force you to have forced outage. Component integrity also become an issue here, the loosening component of the rotor can lead to high cycle fatigue.

Retaining Rings Problem

Retaining rings is used to restrain the centrifugal force of the rotor winding end turns. This is the most or the highest stressed components of the generator. The most failure at the retaining rings section is due to stress corrosin cracking (which also influenced from the retaining rings materials itself). The failure or damage on retaining rings could result in a catastrophic failure

Infrared thermography, what was that ? what should i know about that ? do i have to implement it ? there is some question that some maintenance people will ask about infrared thermography, and many questions will follow at the back.

Today, it is a little bit late if your plant or your facility doesn’t implement infrared thermography as a integrated part of your maintenance program. A lot of benefits that you can get by implementing thermographic inspections to your equipment because it is very powerful program that let you to know your equipment in “realtime” condition without having any shutdown and it will become your eyes to looking for some abnormal condition during maintenance and inspections. here are some benefit of infrared thermography program :

Saving Time

With infrared thermography inspection, your equipment condition can be inspected “realtime” and as it is, with thermography, you will know if your equipment is healthy, or having “abnormal condition” such as wear, temperature anomally, missalignment and other abnormal patterns. with the program, you can also save your time related to production, because it is not necessary to shutdown the equipments during inspections, you can continue the production while maintenance people perform the inspections. so that your machine can continuous running and keep producing profit for you.

Saving Money and Budget

Can you imagine if your eqipment suddenly fails and perhaps become worse (catastrophic failure) due to lack of identifying the failure before it occur? how much money that you will be spend to fix the failure equipment?, how many hour that you can tolerance the downtime?. for critical equipment at your facilities, infrared thermography program is a must, no excuse, because if your critical equipment stop to work it can be a “disaster” for your company, not only the profit, but also the credibility of your company, for public facilities and utilities, their failure equipment means customer complaints, thats why continuous services must be maintain, and infrared thermography program can support your business need and provide early detection to identify “what happen” with your machine.

Increase Your Safety 

For maintenance people, implementing infrared thermography program means increase safety to their personnel, because they can perform inspections while the equipment is still in online condition. it also can be the safety to the equipment, as soon as maintenance personnel know their equipment condition, they can have faster response to solve the problem increase reliability The most important thing that you can get the benefit from good program like infrared thermography inspections is you can increase your plant reliability and availability,by detecting the problem earlier, you can act better to fix the problem and run your equipment online again without any unscheduled downtime. no matter what is your business core, infrared thermography will give you a better facilities to operate, and it means make more money