Quote 'Above 480V (or 600V where that is used) solidly grounded should never be used, low impedance grounded should be avoided if at all possible (much easier for new installations than existing) and high resistance grounded coupled to a unit transformer is the gold standard. The hybrid...
Hello,
If I want to use one system to filter the same oil for 1 system to 20 micron (1000L) and another system to 40 microns (5000L). Would it only make sense to filter both systems to 20 microns or will the 20 micron filter be much, much slower at filling the system?
I want to simplify the...
Sure +5% on rotor roundness and -5% on stator roundness with 5% error in the offcenter of the rotor compared to the center of rotation plus 5% error in offcenter of stator in the opposite direction. Total error 20%.
Do you have any information on the USBR procedures?
I would prefer an IEC...
Thanks edison,
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...
The 0.003 in number sounds strange since it should depend on the rotor diameter. If you have an 8m rotor or a 1m rotor will make a big difference and that is why CEA guideline is in %. Although it is in % of airgap which will also vary but mostly due to rotor size.
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...
Thank you #21121956!
I have been to many stations with the thrust bearing above the rotor and below the rotor. I am just trying to figure out why one is selected over the other. Now for my real question.
I was reading a tender for a 110MW hydropower station and it was stated that the thrust...
I'm talking about a vertical unit. It can be a kaplan or a francis turbine.
I can not understand your second question.
I am trying to get some opinions about the thrust bearing being located above or below the rotor in these type of units.
Hello,
I have a hydropower question. Which bearing arrangement is more common in hydropower machines the combined thrust/ guide bearing under or over the rotor. I believe it is called umbrella and suspended bearing arrangements. Is one much more common then the other. I'm talking about for...
Hello,
I hope that Marmite is around or anyone else with comments.
I would like to get comments on the following:
It has been suggested that if the generator has a H=3.5 then we need 2 power lines for stability of the grid but if the generator has H=5 then we would only use 1 line.
Is it...
Hello,
Maybe look at the thread I asked about H values last week. I got a very good answer from Marmite.
Basically you have the MVA and the speed and the H value is equal to 1/2Jw^2/MVA. So you just need J. you can look in the equipment spec's, ask the manufacturer or calculate it using for...
Are you designing this thing from scratch?!
Actually the owner was asking for options for differnt H values so they could consider using one or two lines for distribution. I was just asked to look into it.
Thanks again for your help.
Hello,
I have another hydropower generator question. Which bearing arrangement is more common the combined thrust/ guide bearing under or over the rotor. I believe it is called umbrella and suspended bearing arrangements. Is one much more common then the other. I'm talking about for larger...
Thank you, thank you, thank you.
So the H value is dependent on m,r and w of the machine. Would you normally add or reduce weight to the rotor or change the diameter of the rotor to adjust the H?
You say newer machines have a lower H but isn't it better to have a higher H value for system...
I have been to help out with some info regarding a hydropower unit.
What are they talking about when they say inertia requirement in MWs/MVA in ton m2 for a hydropower unit?
What can one do in order to meet inertia requirement?
what is a reasonable value or a upper limit value and what kind...
Rick or Moltenmetal,
Any comments on the no restriction of the word engineer in the act. It is important to clarify the issue. One or possibly two of us are wrong I would like to know. I will fully admit that I am mistaking if you are correct it is just that i was of the same opinion as you...
Well moltenmetal this was also my thinking. I read the entire BC act and could not find the restriction of the title engineer anywhere. It only states that the title professional engineer is prohibited. I assume that is why so many people without licensure are using the title in Canada. If...
