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Re: [atlas_craftsman] FYI VFD

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  • Curt Wuollet
    That s fine, have it your way. But provide input fusing so you never have to apologize for Reliance, Baldor, etc. On a related note: Most VFDs are rated for
    Message 1 of 13 , Jul 4, 2013
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      That's fine, have it your way. But provide input fusing so
      you never have to apologize for Reliance, Baldor, etc.
      On a related note: Most VFDs are rated for limited charging cycles
      per hour. Switching the input on and off frequently stresses the diodes
      and can cause similar damage. Using the drive start and stop is much
      less stressful on everything. The AB Powerflex 40 says 80 cycles per hour
      some other drives are as low as 20. I've seen this cause problems where
      a VFD was added to a motor that was cycled like a compressor or some
      pumps. Machine spindles are often used this way.

      Regards

      cww


      On 07/04/2013 02:28 PM, jerdal@... wrote:
      > Yes I do.... ecept that tehy may have had help from lousy solder, and
      > undersizing. The silver strips on top were where solder was SUPPOSED TO
      > add cross-section, but unfortumately it apparently did not, from teh
      > close-up shots. Still, they appearsd to be adequate and some otehr cause
      > was the issue... something INSIDE the unit WRONG FROM THE FACTORY.
      >
      > Single-phase? Do not make me laugh..... 7.5 kW unit..... run at 1.5 HP
      > single phase?... phooey.... We run units at single phase all teh time and
      > they don't blow up or melt traces at that extreme de-rating. Mostly the ones
      > we deal with are good at single phase full HP. Some 50% derate I also
      > design VFDs.... so I know how to spec things
      >
      > That unit should not have had that failure, and no amount of apologizing for
      > cheap chinese goods can cover that point up...
      >
      > JT
      >
      >
      > ----- Original Message -----
      > From: "Curt Wuollet" <wideopen1@...>
      > To: <atlas_craftsman@yahoogroups.com>
      > Sent: Thursday, July 04, 2013 9:52 AM
      > Subject: Re: [atlas_craftsman] FYI VFD
      >
      >
      >> Looks like a simple overload.
      >> The traces simply melted due to excessive current. You can't size
      >> everything to withstand all the current the source can provide.
      >> If it were configured properly, it should have shut down from excessive
      >> motor current. In a single to three phase application the input current
      >> increases much faster than the output current. Misapplication/operator
      >> error. Unless you believe the traces weren't sized to carry rated input
      >> current.
      >>
      >> Regards
      >>
      >> cww
      >>
      >>
      >>
      >>
      >> On 07/04/2013 08:28 AM, jerdal@... wrote:
      >>> Per the Huanyang, here is an amusing video of the failure and repair of
      >>> one
      >>> of their delightful VFDs.... Note the failure mode of simply burning up
      >>> the
      >>> traces on the PWB.... possibly from single phase input, possibly not.
      >>>
      >>> http://www.youtube.com/watch?v=lNkf_0DCb4s
      >>>
      >>> The quality of construction is "interesting".....
      >>>
      >>> JT
      >>>
      >>> ----- Original Message -----
      >>> From: "warrengrant" <warrengrant@...>
      >>> To: <atlas_craftsman@yahoogroups.com>
      >>> Sent: Friday, June 28, 2013 3:50 AM
      >>> Subject: [atlas_craftsman] FYI VFD
      >>>
      >>>
      >>>> In reading some info on the VFD for my Mill I had overlooked something.
      >>>> Since there has been some discussion in the past about VFDs I thought
      >>>> this
      >>>> may be of interest to some. The Drive I have is Huanyang that I
      >>>> purchased
      >>>> on Ebay. This may be of some help to you. I don't know if other VFDs
      >>>> have the same problem but I can see where the capacitors could go weak.
      >>>> I
      >>>> will be starting mine about every other month after reading this just to
      >>>> be on the safe side as I have two of these. I also have an Eaton VFD
      >>>> but
      >>>> I don't have a manual so I will do the same for it. Hope this helps.
      >>>> Warren
      >>>>
      >>>> "It is better not to store the inverter for long time. Long time storage
      >>>> of the inverter will lead to the deterioration of electrolytic capacity.
      >>>> If it needs to be stored for a long time make sure to power it up one
      >>>> time
      >>>> within a year and the power-up time should be at least above five hours.
      >>>> When powered up the voltage must be increased slowly with a voltage
      >>>> regulator to the rated voltage value."
      >>>>
      >>>>
      >>>>
      >>>>
      >>>> ------------------------------------
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      >>>
      >>
      >>
      >> ------------------------------------
      >>
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      >>
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      >>
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      >>
      >> The Atlas-Craftsman Wiki is at
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      >> Please submit things you think will be useful to Jon Elson at
      >> mailto://elson@...! Groups Links
      >>
      >>
      >>
      >
      >
      > ------------------------------------
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      >
      > To see or edit your personal settings, view the photos, files or links http://groups.yahoo.com/group/atlas_craftsman/
      >
      > The Atlas-Craftsman Wiki is at http://pico-systems.com/cgi-bin/Atlas-wiki/Atlas.cgi
      > Please submit things you think will be useful to Jon Elson at mailto://elson@...! Groups Links
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      >
      >
    • jtiers
      Any quality VFD will have a precharge circuit..... and that drastically reduces the problems with turn-on. Turn-on is otherwise a stressor for the diodes and
      Message 2 of 13 , Jul 4, 2013
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        Any quality VFD will have a precharge circuit..... and that drastically
        reduces the problems with turn-on. Turn-on is otherwise a stressor for the
        diodes and for the bus capacitors. Most small VFDs have precharge, and I do
        not know of even one large VFD that does not have a precharge circuit.
        Small ones use a resistor and relay, large ones typically use an SCR
        pre-charge. SCR types have no particular operation limit, since teh SCR is
        rated for full input, but the relay and resistor type have limits based on
        resistor heating for multiple turn-ons.

        I definitely agree, it makes NO sense to remove power and apply it again
        many times per hour. Far better to use the provided "enable" input. That
        may entail some re-wiring, but it is worth the trouble.

        Only if there is a stringent energy saving requirement might the power
        on/off make *some* sense, and in such a case the VFD will need to be
        designed to handle that. Even in that extreme case, I would expect that
        some reasonable design work would let the unit satisfy the requirement while
        maintaining a power connection.

        In any event, the subject Huanyang unit didn't fail in a diode or capacitor.
        And, it probably has a precharge, based on the "T-90 style" relay I saw
        (there would need to be more than one, since that type isn't rated for high
        voltage DC as found after the rectifier.)

        The Huanyang are known for a fairly high incidence of rapid failures, often
        with a "lightshow", although some work for long periods trouble free.
        Other brands have failures also, but they tand to be varied, dead analog
        inputs, bad outputs, display problems, etc, not concentrated in the power
        circuits. Just a word to the wise.... which is hopefully sufficient.

        I expect we have beaten this horse thoroughly, and should bury him.

        JT

        ----- Original Message -----
        From: "Curt Wuollet" <wideopen1@...>
        To: <atlas_craftsman@yahoogroups.com>
        Sent: Thursday, July 04, 2013 3:12 PM
        Subject: Re: [atlas_craftsman] FYI VFD


        > On a related note: Most VFDs are rated for limited charging cycles
        > per hour. Switching the input on and off frequently stresses the diodes
        > and can cause similar damage. Using the drive start and stop is much
        > less stressful on everything. The AB Powerflex 40 says 80 cycles per hour
        > some other drives are as low as 20. I've seen this cause problems where
        > a VFD was added to a motor that was cycled like a compressor or some
        > pumps. Machine spindles are often used this way.
        >
        > Regards
        >
        > cww
        >
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