how to calculate the foundation for a 2 MW generator
how to calculate the foundation for a 2 MW generator
(OP)
I´m trying to define the foundation for a 2 MW syncronous generator, and I don´t know how to calculate the next things maybe someone of you could help me....
How can I calculate the short circuit torque and how to use it for the calculation of the foundation... this is a horizontal hydro unit with francis runner....
What is the best option: double T asembly or a piece of metal mechanized with the holes for the bolts of the generator??
sorry for my badly english and I hope to get some help from you... I´m just trying to know how to know how to do it
thanks in advance
How can I calculate the short circuit torque and how to use it for the calculation of the foundation... this is a horizontal hydro unit with francis runner....
What is the best option: double T asembly or a piece of metal mechanized with the holes for the bolts of the generator??
sorry for my badly english and I hope to get some help from you... I´m just trying to know how to know how to do it
thanks in advance





RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
1000 rpm....
when I write it, I was thinking in get some formula .... or explanation...
I hope someone could help me... I´m new on this mechanical things
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
1000 RPM = 105 Rad/sec
T=P/w = 1.47x10^6/105 = 14,000 lb-ft of torque
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
other question, does somebody knows how to translate lb-ft to kg-metre.
Ah, other question, Sreid, how you get the numbers for the formula
2 MW = 1.47x10^6 lb-ft/sec
why you say 2 MW that valium
thanks in advance to all of you
RE: how to calculate the foundation for a 2 MW generator
Power (lb-ft/sec) = Watts/(746 Watts/HP)X 550 lb-ft/sec/HP
I hate Kg-m as a torque unit. How about Newton-Meter?
RE: how to calculate the foundation for a 2 MW generator
Note that the torque calculated above was the full load torque. You asked about short circuit torque... I'm not sure how one would calculate that.
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RE: how to calculate the foundation for a 2 MW generator
thank to everybody for the attention
and thank sreid for your help, why you hate kg m??
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
Kilogram is properly a mass unit but torque is a force x length unit. I know that Kg Force is a legitament unit of force but I think it creates confusion and leads to mistakes.
RE: how to calculate the foundation for a 2 MW generator
You also need the distance between the holding down bolt holes. ie width across the feet.
Regards
RE: how to calculate the foundation for a 2 MW generator
I'm remembering that case we are talking about a transient where the generator swings against the system. The power is
P= E1*E2*sin(delta)/X
The max possible torque would be where delta approaches 90. I can imagine that would be many times full load torque. Protective relaying should disconnect the generator before it gets there.
Out of phase closing might create torques close to that same maximum.
In the specific case of short circuit, there are large forces on the conductors but as David says I don't think necessarily large torques.
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RE: how to calculate the foundation for a 2 MW generator
cct = circuit, sorry for the confusion.
The short circuit does cause a large torque, albeit only for a few cycles.
Typically:
3 phase short circuit 2 - 5 x FLT
Line to Line short circuit 5 - 9 x FLT
An out of phase synchronism, 180 degrees out, up to 12xFLT.
An out of phase synch is unlikely, so designers ignore that possibility and normally quote the line to line as the worst case.
My little black book gives an approximation to the fault torque as:
1+ (3/2 x (sqrt3)x V^2/(x"d+x2))
So for x"d of 0.18pu and x2 of .2 gives 7.8 x FLT at 100% line volts.
Hope i havent confused you further!
richard
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
"So for x"d of 0.18pu and x2 of .2 " you talk of two reactances...what´s is the name of this reactances???
thanks in advance
RE: how to calculate the foundation for a 2 MW generator
RE: how to calculate the foundation for a 2 MW generator
Torque is only really power for a continuous period. During the very short time of a short circuit the stored magnetic energy disipates in any way it can generates high currents in the stator. These currents create magnetic fields which cause the rotor to accelerate or decelarate which is seen as an accelerating torque. These torques occur for a very short time so there is no useful power produced.
Regards
RE: how to calculate the foundation for a 2 MW generator
Prior to the fault the mechanical torque in is equal to the electrical power out divided by the angular velocity plus losses. Immediately after the fault the mechanical torque is unchanged, the electrical power out has fallen drastically, and the losses remain unchanged. In the short time following the fault, the mechanical power remains unchanged, the electrical power remains at the lower level and the power imbalance causes the shaft to accelerate. As the shaft accelerates the angular velocity goes up, therefore the mechanical torque in goes down. No increase in torque following a fault so long as torque is defined as power divided by angular velocity.