700MW Rotor End Bells Damage
700MW Rotor End Bells Damage
(OP)
Hi all,
I have a question regading 700MW generator rotor.
1. What kind of damage will the generator experience during switch on to stand still (SOS). I have seen pictures of rotor which suffered SOS but not sure exactly what else could go wrong?
2. If say 3000 rpm rotor is turning at lower speed, say 1500 rpm and is suddenly connected to the 5oHz network by mistake, what are the risks to the rotor and stator?
3. Rotor coil retaining rings (end bells), beside supporting the overhang, what else are their purpose? Others are shrink fit while others have end wedge gap?
4. How can one establish that the damage mark on the CRRs (end bells) are mechanical or electrical, how does a concept of fretting link to these?
Your advice will be appriciated.
I have a question regading 700MW generator rotor.
1. What kind of damage will the generator experience during switch on to stand still (SOS). I have seen pictures of rotor which suffered SOS but not sure exactly what else could go wrong?
2. If say 3000 rpm rotor is turning at lower speed, say 1500 rpm and is suddenly connected to the 5oHz network by mistake, what are the risks to the rotor and stator?
3. Rotor coil retaining rings (end bells), beside supporting the overhang, what else are their purpose? Others are shrink fit while others have end wedge gap?
4. How can one establish that the damage mark on the CRRs (end bells) are mechanical or electrical, how does a concept of fretting link to these?
Your advice will be appriciated.






RE: 700MW Rotor End Bells Damage
That machine would be blown away from the foundation, I guess.
RE: 700MW Rotor End Bells Damage
If this is a concern of yours, hopefully you have reverse power protective relaying on your system to minimize the damage.
RE: 700MW Rotor End Bells Damage
RE: 700MW Rotor End Bells Damage
The unit will need to have the slot covers removed and any current damaged metal ground away. I have seen units that rolled from zero speed for >5 minute (don't recall how fast it got, say < 500 rpms )and the damage repairable with just removing and cleaning the slot covers.
If excitation, the driving force applied to the rotor will be much greater and mechanical damages will be severe
the purpose of the retaining rings IS to retain the copper end turns of the field. The forces to do so vary as per amount of copper and those the method to retain depends on force imposed. for a 700 MW, 2 pole will be much greater than a 100 mw 4 pole and higher strenght rings and the method of securing (shrink fit) are required.
determing the effect of any imperfection for a high strenght retaining ring requires an expert. and considerable concern when discovered