fbcybil,
Thanks for your comments. Yes at some point if this problem cannot be resolved the rotor will need to be pulled again, and as you say, it should go for dynamic balancing. From your comments on ecentricity it will be wise to check the run-out of the shaft surfaces and the poles shoes...
ScottyUK,
Thats a good idea. I am going to log the field current under MVAR regulation and constant power after we increase the load to full power. If there are temperature sensitive turn shorts then we should see the excitation trying to compensate for this as they occur. At the same time I...
Thanks ScottyUK,
I will try to organise a test to check for relationship between excitation and vibration at constant MW and also constant MW and variable excitation. I agree that you would think that salient pole would be less effected, unless there was multiple shorted turns which is not...
We have had a 12MW alternator rotor recently rewound. 4 pole, Salient type, brushless excitation system. After installation it was found to have vibration which whist cold was of relativly low level but increases as the machine is loaded. The vibration level appears to increase as the...
We are planning to inspect a Siemens 4 pole 38MW Generator (type TL11 124/19-15) shortly. This is a steam turbine driven (via gearbox)machine with air cooling, air to water heat exchanger. It has been in service for 10years (Manufactured in 1995) but only approx. 7months per year actaul running...
I would agree with everyone here. The decision to use VPI or not is very application dependent. If it is a demanding application in terms of thermal dissipation due to overload then VPI would be reccommended. Having said this 11 hours is a very very short time. I have seen 750kW mining haul...
Generally the greasing regime will be motor specific. The greasing frequncy, amount and type will have be selected by the manufacturer on the basis of the motor and bearing design. Relavent factors are grease cavity size, is there a grease relief drain, normal running/ambient temperature...
The majority of the loss will be carried by heat conduction through the insulation to the room or along the cables to the switchgear and to the room depending on how much dissipation there is in the switchgear itself. Generally there would be little if any power conducted away from the room...
Normally, if a flashover occurs there is a continous arc between brush holders. This will cause melting of the brush holder metal and damage the brushes/pigtales ect (pigtales may be severed). The commutator riser and vee ring creepage bands are also often burnt. Once a flashover occurs very...
