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  1. electricpete

    Centrifugal pumps running in parallel, one pump with high vibration

    Pump B could be the weakest pump. So when run alone it is at a happy point on the curve but when run in parallel it is pushed too far to the left where the vibration may be higher and the current may be lower.
  2. electricpete

    Large Generator Exciter Air gap

    You can further characterize the situation by rotating the rotor 90 degrees and repeating the measurements. If the gap readings remain the same for each clock position (relative to the stator), that tells you the rotor axis of rotaiton is offset with respect to the stator bore axis. If the...
  3. electricpete

    Centrifugal pumps running in parallel, one pump with high vibration

    I feel like I need glasses when I try to read those plots (better graphical resolution would help!) I'm also lacking enough imagination to understand the physical layout shown... is that top view or side view? Are these vertical or horizontal pumps. If the system flow resistance is steady...
  4. electricpete

    Tilting pad journal bearing design

    That's different than what I was envisioning in my last response. I was envisioning the type of pad described by JJPellin which has a single pivot point in the back. That's an older style that I am familiar with. I do believe it will have the limitation that the pivot either needs to be in the...
  5. electricpete

    high vibrations in pd pump, gearbox, motor combo on movable base

    ouch, sorry to hear that. I guess it's a "learning opportunity". Let us know what you find out!
  6. electricpete

    TurboGenerator Journal Bearing Shaft Surface Finish - Too fine?

    Thanks, LPS for that literature link (the first result was relevant). Clearly there's a lot more to the subject than can be gleaned from a standard textbook on hydrodynamic bearings (which would tell us the velocity of the lubricant matches the velocity of the solid at their boundary...
  7. electricpete

    TurboGenerator Journal Bearing Shaft Surface Finish - Too fine?

    I agree too smooth might be a consideration for driving oil rings. But my post had nothing to do with oil rings (The Kingsbury quote referenced had nothing to do with oil rings, the turbine at our plant has journal bearings with forced lube, no oil rings). I will link a thread from another...
  8. electricpete

    Tilting pad journal bearing design

    I would think the curvature of the front of the pad (facing the journal) is critical but the curvature of the back seems relatively unimportant since it contacts nothing except at the small area of the pivot support (rocker). Are you asking about that rocker geometry?
  9. electricpete

    Time Domain Test Data Interpretation in Frequency Domain!

    Ok, so let's say your test duration is 10 seconds. Then you can say the event "occurred 50 times in 10 seconds, which is an average rate of 5 events per second" I'm not trying to be a wise guy, just proposing what seems reasonable to me. But it's not clear to me what you are trying to achieve...
  10. electricpete

    VFD, Motor, Vibration

    You have good responses above. Just to look at another piece: Did that reconnection of the WAT motor to another vfd involve moving the motor (changing it's mounting and potentially its resonance characteristics)
  11. electricpete

    SKF Bearing identification

    In skf terminology, washers can be inserted between bearing outer ring face and housing for sealing purposes or for spacing purposes. https://www.skf.com/us/products/industrial-seals/power-transmission-seals/sealing-and-spacing-washers Perhaps a bearing part number identified as dual housing...
  12. electricpete

    high vibrations in pd pump, gearbox, motor combo on movable base

    Now with benefit of the photo, I get the feeling it is resting on 2 jackscrews on the NDE and supported by the gearbox flange mount on the DE. agreed. It's a plate on stilts. The stilts can bend (which might be be expected to give directional vibration in the horizontal or axial direction), or...
  13. electricpete

    high vibrations in pd pump, gearbox, motor combo on movable base

    Thanks for the spectra. I didn't understand the terminology reduced speed spectrum.... is that just identifying that the reading was taken on the pump end of the gearbox, or was the motor speed changed between spectra? In your picture what the heck is going on underneath the pump and motor? It...
  14. electricpete

    TurboGenerator Journal Bearing Shaft Surface Finish - Too fine?

    You're asking in an electric motor forum and I believe the responses you got are correct for electric motors and small generators I would not assume they are correct for turbines and generators of all types, especially larger ones which can be highly engineered machines. OEM should be...
  15. electricpete

    Inexplicable motor failures

    ok i missed that part but I'm still skeptical. How did you measure current and how accurate do you think those measurements are? were these read off a relay or a clampon? were they steady state or transient. where did you measure the voltage at? if this was a transient did you measure it at...
  16. electricpete

    Inexplicable motor failures

    on a 500hp motor probably form wound, the likelihood that you have shorted turns which did not immediately progress to ground fault but instead somehow caused overload trip seems pretty darned small. i think you've gone in the wrong direction. you never answered the question how you determined...
  17. electricpete

    high vibrations in pd pump, gearbox, motor combo on movable base

    There are a lot of possibilities for causes of high vibration. frequency will help narrow things down. if it is pressure pulsatioin then you'd expect to see pump speed times number of pistons frequency in the vibration. gearmesh frequency is a common source of vibration on gears. having a...
  18. electricpete

    high vibrations in pd pump, gearbox, motor combo on movable base

    As Tmoose would say: What's the frequency Kenneth? Also is the pattern directional? Is it a firm attachment to the motor or as you say "rests". If rests then I'd be inclined to see what happens if jackscrews are backed away.
  19. electricpete

    Inexplicable motor failures

    > Recently, motor #2 tripped twice on overload while running at a very low mechanical load > They were about 105% of the FLA, and there was some imbalance, about 2%. The pump was running at about 1/5 or 1/6 of it's rated load, but the motor was drawing more than it's FLA. How did you determine...
  20. electricpete

    I&C Engineer for Nuclear Industry

    I wouldn't recommend spending a lot of time preparing for a job you don't have. Instead I would look at nuclear plant engineering job advertisements (preferable with the plant or utility rather than a headhunter) for jobs you might be somewhat qualified for. Then tailor your resume to the...

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