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  1. Replies
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    More example of the frustration of dealing with...

    More example of the frustration of dealing with an issue at a distance. I learned never to take a customer's word and especially never, never, never take a salesman's word for anything. Go there and...
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    In two places I ha some dealings with, Peabody...

    In two places I ha some dealings with, Peabody #10 mine, near Springfield, IL and Rock Island Arsenal, they had both MGs and solid state supplies, for powering the trains in the mine and big plating...
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    How many thousand posts are there here of people...

    How many thousand posts are there here of people balancing RPCs by reading the voltages? With that starting load, the voltages are almost sure to be way off and in effect the phase converter is not...
  4. The worst are people who think you are running a...

    The worst are people who think you are running a fixit shop. Like the time someone recommended me to repair the monitor on a Meistergram sewing machine, the type that generates logos on hats and...
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    HE DIDN'T POST THE VOLTAGE AND PHASE ANGLE OF THE...

    HE DIDN'T POST THE VOLTAGE AND PHASE ANGLE OF THE GENERATED PHASE WHEN TRYING TO START!!!!!

    Without that, the rest is pointless. What does it take to get a simple point across? That leg is...
  6. Why bother? A Dahlander motor rated 2 hp at high...

    Why bother? A Dahlander motor rated 2 hp at high speed is rated 1 hp at half speed, that is- same torque, half RPM. A Dahlander motor on high speed fed with a VFD will develop the same torque at half...
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    It was working on a regular three phase line....

    It was working on a regular three phase line. Running on a converter is a whole different problem. First he has to see if the required current is even available.

    Then, instead of shotgun...
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    A VFD will be current limited and may not supply...

    A VFD will be current limited and may not supply enough to overcome starting friction. A soft start ramping up is exactly what you don't want. You want to hit the motor with enough current to...
  9. On the ones I have put drives on I left the motor...

    On the ones I have put drives on I left the motor on high speed and controlled with just the drive. You don't want to switch the output of the drive with power on. Probably the simple solution is to...
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    Before all this, why don't you measure the...

    Before all this, why don't you measure the voltages between each leg you have now, running unloaded and when trying to start. You could produce more wisdom than has been expressed here with a Wiggy....
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    If there is a belt in the power train, you my...

    If there is a belt in the power train, you my only need a longer one and an idler to control tension.

    Bill
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    If you do it right, the generated phase is as...

    If you do it right, the generated phase is as good as the others. If you have the same voltage and phase angle, the motor doesn't now the difference and it produces full power. You can do it with...
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    [QUOTE=thermite;3490939] - bring the present...

    [QUOTE=thermite;3490939]
    - bring the present idler online.

    - drop the supplementary idler(s) onto the line. I'd use two. Ten hoss, each. His 20 HP becomes either of a 20 HP, 30 HP or a 40 HP. ...
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    Since I work primarily in the electronics field,...

    Since I work primarily in the electronics field, they just come around, often for little or nothing. For example, a technician who works for the Barns-Jewish hospital complex took home two Tektronix...
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    Connect the common of the scope input to the line...

    Connect the common of the scope input to the line neutral and the input to the generated leg. I don't know what kind of sweep control you have but you want to have it synched to the 60 cycle line....
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    Not if you are running on a real three phase...

    Not if you are running on a real three phase line. Except for a few that use only a motor that is rope or pony started, RPCs will have a capacitor from one side of the line to the generated phase. A...
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    It is a safe bet that his generated phase is...

    It is a safe bet that his generated phase is somewhere beyond Saturn's orbit when he puts such a heavy load on it. Reducing the starting current may help keep it at a reasonable phase angle. As I...
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    Correct, it is a common method to start in WYE...

    Correct, it is a common method to start in WYE and switch to delta after it gets going. Some of the big grinders I work on have load meters and on startup they draw almost exactly the same current as...
  19. Many years ago some kids in The Rolla School of...

    Many years ago some kids in The Rolla School of Mines turned a bar into shavings enough to fill an automobile, stuffed it in a junk car, towed it into the center of town, and lit it. Back then the...
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    A fellow I met in high school plagued me for a...

    A fellow I met in high school plagued me for a decade. He was unable to do linear logic, if A is true and B is true, then C is true. He operated by a set of platitudes and if the one in use was...
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    When I was in the foreign car repair business, an...

    When I was in the foreign car repair business, an old timer would sometimes come around and help out. One day he was putting the head on an MGA engine, using a 3/8 ratchet.

    "What are you torquing...
  22. Not so. The smaller the aperture, the poorer the...

    Not so. The smaller the aperture, the poorer the resolution. See Dawes limit.

    dawes limit formula - Google Search

    Bright light may help you see better and stopping down the aperture increases...
  23. One plant had several injection molding machines...

    One plant had several injection molding machines that had been in another location, presumably on 240V. I was hired as part of the expansion into the new building, so the machines were already there...
  24. I know just what this is. For years I had a...

    I know just what this is. For years I had a problem from working with an eye loupe and my eyes would go bonkers when I looked in the eye testing instruments in the pilot's medical. I finally found...
  25. I have had to deal with two plants with 120/208...

    I have had to deal with two plants with 120/208 services and hated both. Their only value is to save the contractor money. 240 volt motors will run on 208, but don't develop rated horsepower and run...
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