Hydropower Generator Airgap
Hydropower Generator Airgap
(OP)
Does anyone know of a standard for the % error in airgap, rotor roundness/concentricity and stator roundness/concentricity of a hydropower generator?
The only one I can find is:
CEA - Guide for erection tolerance and shaft system alignmnet.
The values seem a lot higher then what I see used in industry.
The only one I can find is:
CEA - Guide for erection tolerance and shaft system alignmnet.
The values seem a lot higher then what I see used in industry.






RE: Hydropower Generator Airgap
They refer to the manufacturer guidelines regarding airgap uniformity and runout
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RE: Hydropower Generator Airgap
RE: Hydropower Generator Airgap
This implies that the stator and rotor roundness & concentricity should also be within 5% of the air-gap value.
* I would go green if only I were not yellow *
RE: Hydropower Generator Airgap
Is there actually a standard or is it like a mechanic using his finger to measure things. Is this just what is 'done' or is it really a standard published by some respected organization.
I disagree that +/- 5% implies 5% error in rotor and stator roundness. I would guess it should be more like 2% deviation for rotor and 8% for stator as it is harder to control.
Also if you had 5% error in concentricity of the stator and rotor and 5% error in stator and rotor roundness you could have a 20% error in the airgap.
RE: Hydropower Generator Airgap
We have built stator cores with diameters ranging from 3 to 12 meters. The ID has has always been within +/- 1 mm of the nominal dia. Right now, we are rebuilding a 50 MW, 10 pole machine core with a dia of 3000 mm and core length of 1600 mm. We got a maximum dia variation of - 0.3 mm to + 0.2 mm.
Could you tell me how 20% error in air-gap will be produced by following the 5% limit ?
* I would go green if only I were not yellow *
RE: Hydropower Generator Airgap
Do you have any information on the USBR procedures?
I would prefer an IEC standard but it looks like it is not possible.
I have seen the results from GE, Alstom and Voith Siemens generators also but in some cases they are not so good as you state. The problem is that some of the contracts state to follow this CEA specification which states:
http://vibrosystm.com/pdf/MECHTOL.PDF
1mm error on a machine with 20mm airgap might not meet the spec.