magnetic wedges against efficiency
magnetic wedges against efficiency
(OP)
Hi
I got a little problem with the efficiency of 4 MW genset, it´s hydro, and 600 rpm so 50 Hz, and in the design it comes without magnetic wedges, now it is needed to rewind, so i was thinking on get more efficiency with magnetic wedges, cause i´m supposing the iron losses will decrease, cause in the old design we have higher losses on iron than we expected.
ok, i wait for your always important help
I got a little problem with the efficiency of 4 MW genset, it´s hydro, and 600 rpm so 50 Hz, and in the design it comes without magnetic wedges, now it is needed to rewind, so i was thinking on get more efficiency with magnetic wedges, cause i´m supposing the iron losses will decrease, cause in the old design we have higher losses on iron than we expected.
ok, i wait for your always important help





RE: magnetic wedges against efficiency
Muthu
www.edison.co.in
RE: magnetic wedges against efficiency
My thought would be not to authorize is unless you have reviewed the design very carefully for adverse effects. I'd think that installing magnetic wedges should tend to increase the stator leakage reactance. That can adversely affect the stability and the voltage regulation. Can decrease short circuit strength which might affect protection strategy. For motors it may affect starting performance but you don't care about that. They also can vibrate out if not installed correctly.... not as much a concern if stator is vpi'd.
That is the risk side of the equation. There is also the benefit side. Muthu indicated there is not as much improvement in losses from mag wedges on salient pole as on smooth-rotor designs.
Just my thoughts fwiw.
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(2B)+(2B)' ?
RE: magnetic wedges against efficiency
RE: magnetic wedges against efficiency
If you have the money, time and highly accurate instrumentation for very low power-factors, you could do a before and after (mag wedges) kinda stuff. I would definitely talk to the OEM before you do such costly experiments.
pete - it is other way about. :)
Muthu
www.edison.co.in
RE: magnetic wedges against efficiency
Thanks
RE: magnetic wedges against efficiency
uhpo:
We need more information to efficiently help you.
Assuming a salient-pole machine, the pole face losses can be quite high if the generator air gap is small and the stator slots are wide. The main portion of these pole face losses may originate in the massive pole end plates. It therefore would be most economical to replace only the end wedges by magnetic ones. Assuming a total iron loss of about 20 kW, I'd guess that the pole face loss portion at present is about 2 to 4 kW in total, depending on the air gap. So you may gain a mere 1 to 2 kW after installation of magnetic wedges, which tend to brittle. Is this worth the risk? Also, in case you want to compare the iron losses before and after rewind (with magnetic wedges) you have to perform a minimum of two calorimetric loss tests (windage and iron). Quite time consuming and costly.
What's the air gap, the overall stator core length and the stator bore diameter? Is it a salient-pole machine?
Wolf
www.hydropower-consult.com
RE: magnetic wedges against efficiency
RE: magnetic wedges against efficiency
uhpo:
Let us have a response to our comments and questions in case they offered "important help" to you.
Wolf
www.hydropower-consult.com