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  1. MetalworkerMike

    Electrical motor selection

    Using a motor that drives from the edge of the flywheel will require far less torque to start which makes it easier to get it up to speed. I was assuming that by driving the flywheel from the edge you can have the motor mounted 'off' the rotating arrangement so that you can have mains power...
  2. MetalworkerMike

    Electrical motor selection

    You mention that the flywheel will be similar to an automotive flywheel.. is there any reason why you can't drive it from the edge? It would be a heckuvalot easier on the motor, and you wouldn't need to use batteries. Mike
  3. MetalworkerMike

    Electrical motor selection

    You're going to have a 10KG flywheel spinning at 500rpm and the whole thing mounted on another platform spinning at 500rpm? That sounds like a scary device. Good luck balancing _that_ sucker. Mike
  4. MetalworkerMike

    Unusual fuse selection?

    The interrupt rating of these things is only 200A? I hadn't checked that. That is nowhere close to decent. I'll have to figure out a way to fit some CC-class fuses in there. Somehow. Mike
  5. MetalworkerMike

    Unusual fuse selection?

    I don't think I have room for CCs, but I'll double check today. I thought it seemed ridiculous to use those fuses, but I always have this nagging thought that _surely_ the guy who designed the cabinet knew something that I don't... Anyway, for now the GMCs will give me a bit of leeway, and...
  6. MetalworkerMike

    Unusual fuse selection?

    I've got two Polytruder extruders and they both have a bunch of Dayton blowers on them (small 110V 7A FLA units) for cooling the barrel. I've found that each of these blowers is running through a Cooper GMA 10A fuse on the hot line. These are wee little 5mmx20mm fuses so they could fit them into...
  7. MetalworkerMike

    Centrifuge AC Induction Motor Requireing 30 Starts Per Hour

    I've worked with the Marathon Black Max motors before some years ago (just small ones, though... 2HP or so). They are remarkably heavy for their size, and just give you a feeling of 'trustworthiness'. I've never had a problem with them, and they certainly worked fine with inverters... I've run...
  8. MetalworkerMike

    How often should belt tension be checked?

    Just as an aside, I happened to be glancing through a manual for a vacuum pump, and the manufacturer specified that the guard be unbolted and the belt tension checked _every_ _week_. You won't see _me_ doing it that often! Mike
  9. MetalworkerMike

    Efficient Motor Modulation

    It makes sense to use a bit more pump than you need because the piping builds up scale, and the impeller wears a bit and everything moves the pump down on its efficiency curve. Unless you really, really enjoy replacing mechanical seals it pays to use a big pump and don't work it hard. Mike
  10. MetalworkerMike

    how to control speed of single phase motor

    Interestingly enough, I was just ordering a new blower for a machine, from Dayton, and these blowers (much smaller than 2.2kw) are only available in two flavours... Shaded pole and PSC. Just thought I'd toss that in. Mike
  11. MetalworkerMike

    How often should belt tension be checked?

    You check tension and alignment (not just tension) when you first install the belts, then I check it after one day, then after one week, in constant-running belts like that. This is because you want to catch any sheave creep early on, and belts stretch the most early in their life. After those...
  12. MetalworkerMike

    Very high inrush current

    rawelk, I spent some time yesterday with a Bussman catalogue and pondered the difference between the class J fuses and the RKs and CCs that are in wide use in our plant. The class Js seem to have the benefits of the relatively compact size of a 250V RK, while protecting to 600V, while keeping...
  13. MetalworkerMike

    Very high inrush current

    Thank you for the kind words, itsmoked. I think that I have decided that my personal threshold with using CC fuses on motors will be 5 horsepower (at 480V or higher). Above that I will use RK-5s or larger. This will avoid wiring issues since I very rarely use thinner than #10 wire for...
  14. MetalworkerMike

    how to control speed of single phase motor

    S.O.L means, to paraphrase, 'out of luck'. Varying the speed of a single phase motor isn't that hard, it's just doing it _accurately_ that is very hard. You can run a single-phase motor of the 'furnace fan' variety through a cheap, household dimmer switch (the kind meant for lighting) and...
  15. MetalworkerMike

    Very high inrush current

    Okay, I think I've got it now. Thanks in large part to the information kindly provided by rawelk, I now know where I went wrong. Firstly, I assumed that a CC time-delay fuse had the same time delay characteristics as an RK time delay fuse. That was incorrect. Secondly, I double-checked...
  16. MetalworkerMike

    Very high inrush current

    Rawelk: I'm having some trouble with your data. I don't have contrary data, but I'm seeing that you're listing a KTK fuse, which is a fast-acting fuse, as having a longer melt time than a LP-CC which is a time-delay fuse. This just doesn't make sense to me. I had looked up the data before...
  17. MetalworkerMike

    Very high inrush current

    This motor had run 'flawlessly' on 30A 250V RK-5 fuses. These fuses never blew for the apparently 7 years that they were installed. When I found 250V fuses in a 600V application I decided to swap them out for 600V fuses. I replaced the 30A 250V RK-5's with a new fuse holder and 30A 600V CC...
  18. MetalworkerMike

    Help with 3 phase motor running at max. rated current

    The posi-drive belts that Gates makes (I think they call them something like 'chain-belt'... I haven't installed one in years) are really, really nice. They are fiendishly expensive, but properly installed they last a good, long time, they have tons of capacity available (I've put single belts...
  19. MetalworkerMike

    Help with 3 phase motor running at max. rated current

    In that cold environment I can't imagine it having a problem running at an amperage within its FLA providing that it is VFD rated at that current, and the vendor doesn't stipulate de-rating for VFD use or something like that. Did you check all three legs for amperage? This is a fairly...
  20. MetalworkerMike

    Overload settings.

    It's kind of amazing that there are so many schools of thought on this issue. That's why I asked about it. It seems that you can ask five guys and get five different answers. The 125% number is one that I have seen bandied about, and the process outlined by 'whycliffrussel' is the one that I...

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