Generator RTD

[nandrade]

I have installed 12 RTD on the 133 Mw Generator stator winding, 4 for each phase. At the time, we have 4 damage. There`s another way to get a realistic value of the winding temperature, by other electric parameters calc???.
Im afraid that we must open the generator, and take off the RTD damage from the slot.

 

[buzzp]

You can measure the RMS current of the generator. This is typically how winding protection is accomplished by monitoring the current. This is how motors are protected against over loads - load increases then so does the temp. This is all correlated with the type of motor. I suppose the same thing could be accomplished using a generator, however, these are not typcially protected from over heating by monitoring the current.
You may be able to come up with your own little formula for calculated the winding temp using your good RTDS and the current in that phase. This is the only way I know to figure out winding temp without actually measuring it.

 

[JensKristinn]

buzzp is right that monitoring current will protect the winding from overload. But there are other possible causes for overheating, such as blocked ventilation ducts in stator, stator core hot-spots, partial discharges etc. The current monitoring will not detect those problems. The only thing I can think of that might help you is a infrared imaging camera, comparing images with older ones (made at similar loading and ambient temp). But this will never replace the RTDs.

 

[byrdj]

Does the stator bars have a cooling system, like circulating water? If so, RTDs are vital for detecting localized heating like JensKristinn stated. Some units monitor a RTD for every bar and have alarm/trip.

Does the generator also have H2 field cooling? If so a pyrite "smoke" detector would detect damage is occurring from a hot spot and used to alarm/trip.

 

[QCE]

Is it a hydro generator? How many coils? How many parallel pathes? Where are the RTDS located in the pathes? Are you monitoring all 12? How did the RTDs fail?

 

[nandrade]

Is a Thermal Generator. It uses air for cooling and have 4 radiators underneath the generator where water circulates. For check the stator winding temperature, we have 12 RTD. 4 for each fase.(total 12). There are 4 damage, because the measure of the resistance in this devices are infinite. They are located in the slots someone under the stator windng.

Additional to this RTD, we also have the Stator teeht temperature (2 lectures), Stator Core temperature (4 lectures), and the temperature of the air inlet/outlet for coolinf for each side (Non driven, driven side).

The problem is that the generator could lost more RTD signal, and we won`t know the temperature of the winding. In case of a temp increase, how to avoid any problem. We used to down the reactive load, but in a dangerous case, we would down the active power.

Also i did a thermal scan, but it isn`t continue like the RTD. I want to know if exist alternatives like a formula to calculate a avg temp for a given load of the generator.

Thanks for ur help