Damper ring of turbo-generators have some duties such as maintaining synchronism (damping the oscillations), decreasing the losses on the surface of the rotor due to pulsating fields in the air gap, start-up performance.
The question is how can it be designed geometrically?
In reference books, the geometry of rotor wedges (cross-section of the active part of dampers) are pertained to the cross-section of armature winding. is is said, the cross-section of rotor wedges must be something between 20 to 30 percent of the cross-section of the armature winding.
Is there other hints on this?
Regarding the cross section of the wedges: "less is more". Ideally, there would be no wedges at all as any slot in the circumference of the rotor introduces some structural weakness. But manufacturing of the rotor would be next to impossible without the slots to lay the windings. Thus, if you can manufacture a generator with wedges of only 10 %, this could result in a design mechanically superior to wedges of 20 ..30 %.
Regards
Hello,
one might imagine a rotor with holes "drilled" for the electrical windings (instead of the milled slots "closed" by wedges). While it would be impractical regarding the "laying" of the windings, I can neither see a "stress problem" nor thermal "challenges" beyond those already in place. But this is only some theoretical excursion. In reality going below 20 % might pose a "real challenge".
Regards
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