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Problem settimg up IMO VFD

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  • Problem settimg up IMO VFD

    I had to replace the inverter drive on my big lathe. The old Telemecanique died. I've been using an ABB that I had lying around as a stopgap, to keep the machine going, but it was a 5kW drive on a 7.5kW motor so was a bit short of grunt.
    I picked up a secondhand IMO VXM750 last week, and have been trying to get my head round the setup. I don't know whether it's just me getting older, but the manual seems very hard to get into.
    Anyway, finally got it wired in & set up somewhere near right, with one exception.
    I've set, or so I think, max frequency to 70 Hz, & minimum to 20 Hz. The speed control pot is exactly the same one I've been using with the previous drives with no problems at all.
    Maximum speed setting gives a rock steady 70 Hz, but minimum hovers around 28 Hz with a bit of fluctuation up & down. I've checked the resistance of the slider on the pot does cover the full range up & down, but it's tricky to measure the voltages at the pot when in operation. I can find a way to do it if needed, though.
    It's a previously used drive & some of the settings it came with were a bit unusual, but I can't see anything that might cause this issue.
    Any suggestions, please?
    Apart from this, it seems to be working absolutely fine.


  • #2
    OK, I've found the answer
    There are two adjustment functions, 'Frequency gain' and 'Frequency bias'.
    I had to tweak these two up & down until the speed pot covered the range that I wanted. Never come across that before!